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NBME 20 Answers

Block 1/Question#1
A 37-year-old nurse is accidentally stuck with a needle used ...
Inhibits reverse transcriptase

Block 1/Question#2
A mother who has toxoplasmosis gives birth to an asymptomatic ...
Antitoxoplasma IgM antibody concentrations

Block 1/Question#3
A 48-year-old man comes to the physician for a routine ...
Upregulation of the LDL receptors

Block 1/Question#4
A 50-year-old man is brought to the emergency department by ...
Formic acid

Block 1/Question#5
A 24-year-old African American man comes to the physician ...
Pseudofolliculitis barbae

Block 1/Question#6
A 16-year-old student has uncontrollable sleepiness, falling ...
Direct transition from wakefulness to REM sleep

Block 1/Question#7
A 5-year-old girl with AIDS develops a progressive ...
Thymidine kinase

Block 1/Question#8
A 10-year-old girl is brought to the physician by her mother ...
Breast bud development

Block 1/Question#9
A 50-year-old man is brought to the physician by his wife ...
Pick disease

Block 1/Question#10
A 77-year-old woman has been having difficulty fastening ...
C7-T1 foraminal stenosis

Block 1/Question#11
The sequence surrounding the first two exons of the human ...
Disruption of normal splicing by creation of a new 3′ splice site

Block 1/Question#12
A 72-year-old woman with dysphagia is undergoing surgical ...
Right kidney

Block 1/Question#13
A 6-week-old girl is brought to the physician by her mother ...
Immature lower esophageal sphincter

Block 1/Question#14
A 28-year-old man who is a migrant worker comes to the clinic ...
Psoas major

Block 1/Question#15
A 30-year-old man who completed a successful course of ...
Adjustment disorder with anxiety

Block 1/Question#16
A 30-year-old woman with multiple sclerosis comes to the ...
Pons

Block 1/Question#17
A 50-year-old woman comes to the physician because of a ...
Drug effect

Block 1/Question#18
A 36-year-old man comes to the physician because he has not ...
Urine output: increased; Urine potassium: increased

Block 1/Question#19
A 60-year-old man comes to the physician because of a 6-week ...
Urine Na+: increased; Serum osmolality: decreased

Block 1/Question#20
An 8-year-old boy is evaluated for ventricular systolic ...
Coarctation of the aorta

Block 1/Question#21
A 75-year-old woman comes to the physician because of a ...
Multinucleated giant cells and neutrophil infiltrates

Block 1/Question#22
A 38-year-old woman comes to the physician because of a 3-day ...
Vagus

Block 1/Question#23
A 34-year-old man who is HIV positive is brought to the ...
CD4+ T lymphocytes

Block 1/Question#24
A 50-year-old man comes to the physician because of a ...
Omeprazole

Block 1/Question#25
A 25-year-old primigravid woman at 42 weeks’ gestation is ...
Phosphoinositide hydrolysis

Block 1/Question#26
Serum cholesterol concentrations are measured as part of a ...
16%

Block 1/Question#27
A 53-year-old woman comes to the physician because of a ...
Schistosoma mansoni

Block 1/Question#28
A previously healthy 16-year-old girl comes to the physician ...
Trichomonas vaginalis

Block 1/Question#29
During an experiment, an investigator isolates an abnormal ...
Lysine

Block 1/Question#30
A 33-year-old woman comes to the emergency department 1 hour ...
Lunate

Block 1/Question#31
A 66-year-old man has had fatigue, shortness of breath, and ...
Focal pulmonary fibrosis

Block 1/Question#32
A 56-year-old woman is brought to the emergency department ...
Placement of the central line via the left internal jugular vein

Block 1/Question#33
A 17-year-old girl comes to the emergency department because ...
Mitochondrial

Block 1/Question#34
A strain of Escherichia coli produces a temperature-sensitive ...
Missense

Block 1/Question#35
A 70-year-old man dies of coronary artery disease. He had a ...
Spastic hemiparesis on the right

Block 1/Question#36
A 56-year-old man is admitted to the hospital after an ...
Rhabdomyolysis

Block 1/Question#37
A 1-month-old male newborn is brought to the emergency ...
Na+: 132; K+: 3.2; Cl: 90; HCO3: 37

Block 1/Question#38
A 9-year-old girl is brought to the physician because of poor ...
Diverticulum of the roof of the embryonic oral cavity

Block 1/Question#39
A 3-month-old boy is brought to the office by his mother ...
Lateral to the inferior epigastric artery and superior to the inguinal ligament

Block 1/Question#40
Monoclonality of neoplastic cells in endometrial carcinoma ...
X chromosome-linked isoenzymes

Block 1/Question#41
A 45-year-old man has fever, chills, dysuria, and a tender, ...
Escherichia coli

Block 1/Question#42
A 60-year-old man has two-pillow orthopnea, severe dyspnea, ...
Jugular venous pressure of 12 mm Hg

Block 1/Question#43
A randomized clinical trial is conducted to compare wound ...
Neither procedure is superior

Block 1/Question#44
A 35-year-old woman with newly diagnosed hypertension comes ...
MR angiography of the renal arteries

Block 1/Question#45
A 2-year-old boy is brought to the physician because of ...
Amino Acids: decreased; Glucose: decreased; Phosphate: decreased; HCO3–: decreased

Block 1/Question#46
A 55-year-old woman comes to the physician for a follow-up ...
Cholecalciferol

Block 1/Question#47
A 60-year-old woman with type 2 diabetes mellitus is brought ...
Rupture of a papillary muscle

Block 1/Question#48
An otherwise healthy 4-month-old girl is brought to the ...
Spontaneous involution

Block 1/Question#49
A 56-year-old man comes to the physician because of a 6-month ...
Fibromuscular hyperplasia of arterioles

Block 1/Question#50
A 26-year-old man undergoes an abdominal exploratory ...
Splenic

Block 2/Question#1
A 17-year-old girl comes to the emergency department because ...
Speak with the patient and her parents about the findings

Block 2/Question#2
Following a wedding reception that was attended by 75 people, ...
Norovirus

Block 2/Question#3
An investigator compares the DNA sequences of a group of ...
5′ CCGG

Block 2/Question#4
A 56-year-old woman has frequently burned herself while ...
Syrinx of the central region of the spinal cord from C-4 to T-5

Block 2/Question#5
A 32-year-old woman has had fecal incontinence since giving ...
Damage to the anal sphincter

Block 2/Question#6
An 18-year-old boy has just been diagnosed with ...
50%

Block 2/Question#7
A 30-year-old man comes to the physician because of a 3-month ...
Increased osteoclast maturation and activity

Block 2/Question#8
Three elderly residents of an assisted living facility in ...
Legionella pneumophila

Block 2/Question#9
An otherwise healthy 16-year-old girl comes to the physician ...
Cold, dry air

Block 2/Question#10
A 70-year-old woman is transferred to a rehabilitative ...
Activity level before the fracture

Block 2/Question#11
A female newborn delivered at 36 weeks' gestation is in ...
Incomplete formation of pleuroperitoneal membrane

Block 2/Question#12
An 80-year-old man with type 2 diabetes mellitus is brought ...
Pelvic splanchnic

Block 2/Question#13
A 25-year-old woman comes to the physician because of a 2-day ...
A phospholipid (cardiolipin) on charcoal particles

Block 2/Question#14
A 23-year-old woman has had fever, hypotension, and ...
Streptococcus pneumoniae

Block 2/Question#15
A 55-year-old man comes to the physician because of ...
Dextromethorphan

Block 2/Question#16
A 10-year-old boy with mild mental retardation is brought to ...
Tuberous sclerosis

Block 2/Question#17
A 57-year old man has a hemoglobin concentration of 18.5 ...
Chronic obstructive pulmonary disease

Block 2/Question#18
A 65-year-old man is brought to the emergency department ...
ST-segment elevation

Block 2/Question#19
A 66-year-old man is brought to the emergency department 30 ...
Cigarette smoking

Block 2/Question#20
A 19-year-old man who is a college student is brought to the ...
Subcutaneous crepitus

Block 2/Question#21
A 25-year-old woman comes to the physician 2 days after ...
Granulomas containing stellate microabscesses

Block 2/Question#22
A 44-year-old woman comes to the physician for a follow-up ...
Ubiquitin ligase

Block 2/Question#23
Which of the following changes in the cardiovascular system ...
Increased basal systolic blood pressure

Block 2/Question#24
A patient with a 1-week history of diarrhea has reduced ...
Decreased arterial Pco2

Block 2/Question#25
A 14-year-old girl is brought to the physician because of a ...
Mitochondrial tRNALeu

Block 2/Question#26
A male newborn is found to have a decreased blood thyroxine ...
Thyroid hormone-binding globulin deficiency

Block 2/Question#27
A 38-year-old African American man with recently diagnosed ...
It should play a role because the efficacy of certain classes of medications varies among different ethnicities

Block 2/Question#28
At a postnatal checkup, a 6-week-old female newborn weighs 20 ...
Annular pancreas

Block 2/Question#29
A 25-year-old woman has a flu-like illness (fever, myalgias, ...
Picornavirus

Block 2/Question#30
A 78-year-old man is brought to the emergency department by ...
Cortisol

Block 2/Question#31
A 25-year-old man comes to the physician 8 hours after the ...
Rupture of an intervertebral disc

Block 2/Question#32
A 12-year-old girl is brought to the physician by her mother ...
Osteoblasts

Block 2/Question#33
A study is conducted to assess the effect of a new screening ...
Lead-time

Block 2/Question#34
A 28-year-old man has excessive thirst and polyuria. The ...
Hypothalamus

Block 2/Question#35
A 36-year-old woman comes to the office because of a 1-month ...
Splenomegaly

Block 2/Question#36
A 31-year-old man has a large, yellow, soft mass deeply ...
Liposarcoma

Block 2/Question#37
A 28-year-old woman of Eastern European Jewish decent comes ...
Recombinational double-stranded DNA break repair

Block 2/Question#38
A 50-year-old woman with a restrictive pulmonary disorder ...
Functional residual capacity: decreased; Residual volume: decreased; Vital capacity: decreased

Block 2/Question#39
A 29-year-old man comes to the physician because of a 1-week ...
Absence of peptidoglycan

Block 2/Question#40
A 70-year-old man has a 3-month history of weakness and a ...
Squamous cell carcinoma

Block 2/Question#41
Purified serum antibodies elicited by immunization with ...
Proteins X and Y express the same epitopes

Block 2/Question#42
A previously healthy 32-year-old woman is brought to the ...
Preload

Block 2/Question#43
An 18-year-old woman comes to the physician because she has ...
Ovaries

Block 2/Question#44
A 43-year-old woman, gravida 2, para 1, at 10 weeks' ...
Nuchal translucency (fetal ultrasound): increased;
Pregnancy-associated Plasma Protein (maternal serum): decreased;
Human Chorionic Gonadotropin (maternal serum): increased


Block 2/Question#45
A new antiplatelet agent is developed for the prevention of ...
8%

Block 2/Question#46
A physician prescribes a newly marketed drug to 45 patients. ...
Discontinue the new drug in affected patients and file MedWatch reports on the FDA's Web site

Block 2/Question#47
A 35-year-old man comes to the physician to discuss donating ...
1:4

Block 2/Question#48
A sedentary 50-year-old man with hypertension comes to the ...
Antidepressant therapy

Block 2/Question#49
An 82-year-old woman is brought to the physician because of a ...
Decreased slope of diastolic depolarization

Block 2/Question#50
A 27-year-old woman comes to the physician because of a ...
Pheochromocytoma

Block 3/Question#1
The frequency of an autosomal recessive disease in a ...
1/25

Block 3/Question#2
A 23-year-old woman is brought to the emergency department ...
Xanthine oxidase

Block 3/Question#3
A 45-year-old woman has a thyroidectomy because of asymmetric ...
Calcitonin

Block 3/Question#4
An 18-year-old woman comes to the physician because of fever, ...
Reactive T lymphocytes

Block 3/Question#5
A 35-year-old man comes to the physician because of a 2-month ...
Methotrexate

Block 3/Question#6
A new drug has the following effects on the activity of the ...
Pathway labeled 'H' (Conversion of Leukotriene A4 to Leukotriene B4

Block 3/Question#7
A 10-year-old boy has a palpable mass in the ventral midline ...
Endoderm of foramen caecum

Block 3/Question#8
A 12-year-old girl is brought to the physician for a ...
Polyubiquitination

Block 3/Question#9
A 62-year-old man comes to the physician because of pain in ...
Prostate

Block 3/Question#10
A 59-year-old man develops fatigue and decreased appetite 3 ...
Hemolysis

Block 3/Question#11
A 3-year-old boy is brought to the physician because of a ...
Heterozygous mutation in the ankyrin gene

Block 3/Question#12
A 46-year-old man has dyspnea, orthopnea, and a midsystolic ...
Mitral regurgitation

Block 3/Question#13
A 45-year-old woman develops proteinuria and hematuria. She ...
Tubulointerstitial nephritis

Block 3/Question#14
During a clinical study, an investigator tests a new drug for ...
Increase the sample size

Block 3/Question#15
A 23-year-old woman, who was diagnosed with Sjögren syndrome ...
Substance P

Block 3/Question#16
A 41-year-old woman with systemic lupus erythematosus is ...
Ask the attending physician to obtain informed consent

Block 3/Question#17
A 45-year-old man comes to the emergency department because ...
Schizoid personality disorder

Block 3/Question#18
An 18-year-old woman comes to the physician to request ...
50%

Block 3/Question#19
A 23-year-old man comes to the physician because of a 1-month ...
Area labeled ‘B’ (Mitochondrion)

Block 3/Question#20
A 67-year-old woman comes to the physician for a health ...
Low sensitivity

Block 3/Question#21
A newborn is born with a lethal chromosome defect. He is ...
Feed by whatever means necessary to maintain comfort

Block 3/Question#22
In patients with breast cancer, metabolically stable agonists ...
Gonadotropin by the pituitary gland

Block 3/Question#23
A 50-year-old woman is brought to the emergency department by ...
pKa: 6.0; Protein binding in plasma: 20%; Volume of distribution at steady state: 1 L/kg

Block 3/Question#24
A 2-month-old girl is brought to the emergency department by ...
Thyroid function tests

Block 3/Question#25
A 4-week-old infant is brought to the emergency department ...
Hypertrophic pyloric stenosis

Block 3/Question#26
A 3-month-old boy is brought to the physician because of ...
Mannose 6-phosphate

Block 3/Question#27
A 55-year-old man with type 2 diabetes mellitus, ...
Pravastatin

Block 3/Question#28
A 23-year-old woman who is 6 months pregnant develops deep ...
Antiplatelet antibodies

Block 3/Question#29
An 83-year-old man is brought to the emergency department ...
Early septic shock

Block 3/Question#30
A 22-year-old woman who recently emigrated from rural Mexico ...
Obstruction of the right interventricular foramen (foramen of Monro)

Block 3/Question#31
A 62-year-old woman comes to the physician because of ...
β-Tubulin

Block 3/Question#32
A 54-year-old woman with terminal metastatic pancreatic ...
Nonmaleficence

Block 3/Question#33
A 31-year-old woman receives a prescription for tetracycline ...
Formation of complexes with mineral ions

Block 3/Question#34
A 22-year-old woman comes to the emergency department because ...
Release of bacterial products

Block 3/Question#35
A 51-year-old man has the acute onset of fever and ...
Cytomegalovirus infection

Block 3/Question#36
A 4-year-old boy has had fever, abdominal cramping, and ...
Shigella sonnei

Block 3/Question#37
A 62-year-old man with alcohol-induced liver disease develops ...
Spironolactone

Block 3/Question#38
A 23-year-old man with a 3-year history of schizophrenia is ...
Psychogenic polydipsia

Block 3/Question#39
A 19-year-old woman has severe refractory pustular acne that ...
Teratogenic effects in the embryo

Block 3/Question#40
Two days after admission to the hospital because of ...
Do not proceed with the transfusion

Block 3/Question#41
A 2-year-old child undergoes resection of the right kidney ...
Increase in glomerular size

Block 3/Question#42
A 13-year-old girl has an episode of severe cellular ...
Epstein-Barr virus genome

Block 3/Question#43
A 71-year-old man comes to the physician because of a 6-month ...
Cilostazol

Block 3/Question#44
A 56-year-old man is brought to the emergency department 30 ...
Capillary hydrostatic: increased; Interstitial hydrostatic: increased; Interstitial oncotic: decreased

Block 3/Question#45
A 39-year-old man reports bright red spots on the toilet ...
Constipation

Block 3/Question#46
Removal of the thymus at birth results in severely impaired ...
Thymic lymphocytes produced before thymectomy are long-lived

Block 3/Question#47
A 60-year-old woman has prolonged apnea following general ...
Succinylcholine

Block 3/Question#48
A 48-year-old woman comes to the physician because of a ...
Hypothyroidism

Block 3/Question#49
A 92-year-old woman who was recently admitted to a nursing ...
Atrophy of dermal collagen

Block 3/Question#50
A 62-year-old man comes to the physician because of a 1-week ...
Agonist at γ-aminobutyric acid B (GABAB) receptors

Block 4/Question#1
A 32-year-old man comes to the physician because of a 3-month ...
Tissue: testicle; Effect: estradiol production

Block 4/Question#2
A study is conducted to identify healthy women at risk for ...
Liver

Block 4/Question#3
A 23-year-old woman comes to the physician for a follow-up ...
Collagen synthesis

Block 4/Question#4
A 20-year-old man comes to the physician stating that food ...
Olfactory

Block 4/Question#5
Immediately after a cerebral infarction, a 62-year-old ...
Area labeled ‘A’ (Broca’s area)

Block 4/Question#6
A 51-year-old man develops diaphoresis, tachycardia, and a ...
Alcohol withdrawal

Block 4/Question#7
A 33-year-old woman with HIV infection is brought to the ...
Non-Hodgkin lymphoma

Block 4/Question#8
A 58-year-old man is brought to the emergency department ...
Hypertension

Block 4/Question#9
A previously healthy 37-year-old woman comes to the physician ...
Tumor of the adrenal zona fasciculata

Block 4/Question#10
A 65-year-old woman who has a 25-year history of chronic ...
Hydroxylation of proline

Block 4/Question#11
A 37-year-old man who is HIV positive comes to the physician ...
Nortriptyline

Block 4/Question#12
An investigator is conducting a randomized, double-blind, ...
Analyze all nonadherent participants according to the group of the study to which each was randomized

Block 4/Question#13
A 62-year-old woman comes to the physician because of a ...
Bronchogenic carcinoma

Block 4/Question#14
A 60-year-old man has a round, semitransparent nodule on his ...
Basal cell carcinoma

Block 4/Question#15
A 45-year-old man is undergoing a surgical procedure. Which ...
Decreasing respiratory rate

Block 4/Question#16
An investigator wishes to determine the effectiveness of a ...
Ductal ion reabsorption is more efficient at low flow rates

Block 4/Question#17
A previously healthy 55-year-old man has recently been ...
Renal artery stenosis

Block 4/Question#18
A 35-year-old man comes to the physician because of a 6-month ...
Gastrin

Block 4/Question#19
A 55-year-old man with severe emphysema comes to the ...
Percussion: hyperresonant; Tactile fremitus: decreased; Expiratory phase: prolonged

Block 4/Question#20
A 5-year-old boy is brought to the physician for a follow-up ...
Hypophosphatemia

Block 4/Question#21
A 47-year-old woman comes to the physician because of a ...
Contact with parakeets

Block 4/Question#22
A 35-year-old man is given cyclosporine following a liver ...
Decreased synthesis of interleukins

Block 4/Question#23
A 45-year-old woman who is intubated and mechanically ...
β-Glucan carbohydrates in the cell wall

Block 4/Question#24
A 27-year-old man comes to the physician because of weakness ...
Deep branch of the ulnar nerve at the hook of the hamate bone

Block 4/Question#25
A 52-year-old man is brought to the emergency department ...
Increased total peripheral resistance and decreased cardiac output

Block 4/Question#26
A 33-year-old man comes to the physician because of a 3-week ...
Rectus femoris

Block 4/Question#27
An investigator is studying patients with West Nile virus ...
Case series

Block 4/Question#28
A 78-year-old man dies of chronic congestive heart failure. ...
Failure of the Na+–K+ pump

Block 4/Question#29
A 15-year-old girl is brought to the physician by her mother ...
Doxycycline

Block 4/Question#30
A 32-year-old woman is brought to the emergency department 20 ...
Arterial laceration

Block 4/Question#31
A 48-year-old man is brought to the emergency department 12 ...
Cl-: 96 mEq/L; HCO3-: 8 mEq/L

Block 4/Question#32
A 55-year-old man comes to the physician because of a 2-month ...
Partial oxidation of fatty acids

Block 4/Question#33
A 65-year-old woman with cardiovascular disease is found to ...
Increased bile salt

Block 4/Question#34
A 20-year-old man is brought to the physician by his mother ...
How frightening for you to see your son like this. Do you have any idea about what might be causing his behavior?""

Block 4/Question#35
A 62-year-old man comes to the physician for a follow-up ...
Contemplation

Block 4/Question#36
A 25-year-old woman is brought to the emergency department ...
Factitious disorder

Block 4/Question#37
A 16-year-old girl with cystic fibrosis is brought to the ...
Vitamin E

Block 4/Question#38
A 45-year-old man comes to the physician because of ...
Tumor necrosis factor

Block 4/Question#39
A 30-year-old woman develops serum sickness following ...
C3a

Block 4/Question#40
A 6-month-old girl is brought to the emergency department by ...
Ornithine transcarbamylase

Block 4/Question#41
A 56-year-old man with a 20-year history of chronic back pain ...
Naloxone

Block 4/Question#42
A 65-year-old woman dies 6 months after the onset of severe ...
Meningeal

Block 4/Question#43
A physician is assigned to a search and rescue team ...
Negative nitrogen balance

Block 4/Question#44
A 45-year-old man comes to the office for counseling prior to ...
Starchy foods

Block 4/Question#45
A 12-year-old boy is brought to the physician for further ...
Terminal components of complement

Block 4/Question#46
A 28-year-old woman at 32 weeks' gestation comes to the ...
Obstructive uropathy

Block 4/Question#47
A 61-year-old man has erectile dysfunction due to spinal cord ...
Area labeled ‘D’ (Corpus cavernosum)

Block 4/Question#48
A 24-year-old man comes to the emergency department because ...
Lipoprotein lipase

Block 4/Question#49
A 23-year-old woman sustains significant blood loss in a ...
Direct antiglobulin test

Block 4/Question#50
A previously healthy 16-year-old girl is brought to the ...
Prescribe antibiotics without notifying her parents

Recent comments ...

... hayayah made a comment on nbme20/block1/q#1 (A 37-year-old nurse is accidentally stuck with a...)
 +1  upvote downvote
submitted by hayayah(603)

NRTI's are associated with possible side effects of anemia, granulocytopenia, and myelosuppression.

sympathetikey  Especially zidovudine.
fmub  Nucleoside reverse transcriptase inhibitors (NRTIs) block reverse transcriptase (an HIV enzyme). HIV uses reverse transcriptase to convert its RNA into DNA (reverse transcription). Blocking reverse transcriptase and reverse transcription prevents HIV from replicating.
... sirminalot made a comment on nbme20/block1/q#1 (A 37-year-old nurse is accidentally stuck with a...)
 -17  upvote downvote
submitted by sirminalot(-73)

[special]

... divya made a comment on nbme20/block1/q#1 (A 37-year-old nurse is accidentally stuck with a...)
 +0  upvote downvote
submitted by divya(29)

For anyone interested, the current post exposure prophylaxis regimen contains - Tenofovir + Emtricitabine + Raltegavir

Link for PEP prophylaxis following occupational exposure

... hayayah made a comment on nbme20/block1/q#2 (A mother who has toxoplasmosis gives birth to an...)
 +6  upvote downvote
submitted by hayayah(603)

The baby does not get any maternal IgM, IgA or IgE as they do not cross the placenta, so if IgM is found it may suggest the baby has encountered an infection in utero.

IgG is passed down to the baby as a means of passive immunity until the baby can form their own antibodies of different types. So if you see anything other than IgG (e.g. IgM) you know it must be d/t an infection.

hungrybox  The baby gets IgA via breast milk.
mbourne  @hungrybox, this is true. However, IgM antibodies are the first antibodies endogenously produced before class-switching occurs. So IgM antibodies in a newborn suggests infection.
... xxabi made a comment on nbme20/block1/q#3 (A 48-year-old man comes to the physician for a...)
 +3  upvote downvote
submitted by xxabi(145)

Statins decrease cholesterol synthesis, which indirectly Statins indirectly cause increased LDL receptor expression on hepatocytes (increases LDL clearance from circulation).

... hellohello made a comment on nbme20/block1/q#3 (A 48-year-old man comes to the physician for a...)
 +0  upvote downvote
submitted by hellohello(0)

I had some trouble understanding why they didnt ask about the inhibition of HMG-Coa reductase so did some more research into the LDL receptor pathway that I wasnt aware of. It appears to be the major contributor to the decreased cholesterol levels. Here is a good synopsis of the LDL upregulation pathway:

"Liver cells sense the reduced levels of liver cholesterol and seek to compensate by synthesizing LDL receptors to draw cholesterol out of the circulation. This is accomplished via proteases that cleave membrane-bound sterol regulatory element binding proteins, which then migrate to the nucleus and bind to the sterol response elements. The sterol response elements then facilitate increased transcription of various other proteins, most notably, LDL receptor. The LDL receptor is transported to the liver cell membrane and binds to passing LDL and VLDL particles, mediating their uptake into the liver, where the cholesterol is reprocessed into bile salts and other byproducts. This results in a net effect of less LDL circulating in blood."

... md_caffeiner made a comment on nbme20/block1/q#3 (A 48-year-old man comes to the physician for a...)
 -1  upvote downvote
submitted by md_caffeiner(11)

this question is gramatically wrong, just move on. i did not and wasted maybe 5 minutes. just know that when you decrease chol. , there is no chol. left, so LDL regulating people open more receptors to balance the chol. back to its normal.

md_caffeiner  and if you dont even remember what makes what, just know that when ldl is getting into the cell via ldl r., it is going directly to make some chol.
... hayayah made a comment on nbme20/block1/q#4 (A 50-year-old man is brought to the emergency...)
 +9  upvote downvote
submitted by hayayah(603)

Methanol is toxic by two mechanisms:

First, methanol can be fatal due to its CNS depressant properties in the same manner as ethanol poisoning.

Second, in a process of toxication, it is metabolized to formic acid via formaldehyde in a process initiated by the enzyme alcohol dehydrogenase in the liver. Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase (ALDH).

Formate is toxic because it inhibits mitochondrial cytochrome c oxidase, causing hypoxia at the cellular level, and metabolic acidosis, among a variety of other metabolic disturbances.

sugaplum  Good pictograph comparing methanol, alcohol, and ethylene glycol. https://wikem.org/wiki/File:Toxic_alcohol_ingestion.JPG
... flexatronn made a comment on nbme20/block1/q#4 (A 50-year-old man is brought to the emergency...)
 +1  upvote downvote
submitted by flexatronn(1)

This is metabolic acidosis with a HIGH anion gap, this scenario involves the "M" (methanol aka formic acid) in the mnemonic "Mudpiles"

Classic scenario for methanol (as per B&B) is suspected ingestion, suicide, alcoholic.....symptoms include confusion, VISUAL symptoms, HIGH AG metabolic acidosis

Treatment: Inhibit alcohol dehydrogenase or Ethanol

... hayayah made a comment on nbme20/block1/q#5 (A 24-year-old African American man comes to the...)
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submitted by hayayah(603)

Foreign body inflammatory facial skin disorder characterized by firm, hyper-pigmented papules and pustules that are painful and pruritic. Located on cheeks, jawline, and neck.

Commonly occurs as a result of shaving (“razor bumps”), primarily affects African-American males.

Images: shorturl.at/fpwY1

tyggles  A good way to remember this is that the word Barber comes from the French for beard (barbe) and these rashes will be in the distribution of a beard.
... hungrybox made a comment on nbme20/block1/q#5 (A 24-year-old African American man comes to the...)
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submitted by hungrybox(433)

I did this by process of elimination:

Acne is not itchy or painful from my experience (Choice A).

Never heard of cutaneous lupus eryhtematosus, but I'd asssume you'd have a malar rash (involving the nose/undereye area), not spread out over the cheeks, jaw, and neck (Choice B).

Keloids are just overgrown scars. Scars are not particularly itchy or painful (Choice C)

Rosacea is just redness/flushing in certain areas of the skin. Mainly an aesthetic issue. Not itchy or painful (Choice E).

tbh I was between B and D.

... lilyo made a comment on nbme20/block1/q#5 (A 24-year-old African American man comes to the...)
... drdoom made a comment on nbme20/block1/q#6 (A 16-year-old student has uncontrollable sleepiness,...)
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submitted by drdoom(370)

This is an interesting one. I like to remember it this way: in people with narcolepsy, all the “right kinds” of sleep are happening at all the “wrong times” of day. During the day, when a power nap would typically throw you immediately into REM, this kid is only entering Stage 1 or 2 (lightest sleep = slightest noises jar him back to reality). At night, when he should peacefully drift into Stage 1, 2, and so on, he instead completely zonks out. Classic narcolepsy.

From UpToDate: “Narcolepsy can be conceptualized as a disorder of sleep-wake control in which elements of sleep intrude into wakefulness and elements of wakefulness intrude into sleep.”

chextra  Isn't REM a rather light sleep stage? Brain waves during REM are very similar to awake states. I think you even wake up briefly in the middle of REM sleep. I don't think FA gave me a great understanding of narcolepsy, but I see it as going from awake to REM (light) for any kind of sleep, daytime or night time.
sammyj98  I'm definitely not ace on this subject, but I think the brain waves present in REM are similar to wakefulness because of the dreaming component. I think of it as though the brain has to go through a process of hypnotizing the body into a state of relaxation, and then properly paralyzing it, and then it can simulate wakefulness (dreaming) to go through with it's defragging of the hard drive. So REM is actually the deepest sleep because the body is fully paralyzed. Please someone correct me, this is probably an inacurrate perspective.
pg32  FA says that narcolepsy has nocturnal AND NARCOLEPTIC sleep episodes that start with REM sleep... So is @drdoom correct? FA seems to disagree regarding the daytime sleep pattern.
... hayayah made a comment on nbme20/block1/q#6 (A 16-year-old student has uncontrollable sleepiness,...)
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submitted by hayayah(603)

In narcolepsy, there is a direct transition from wakefulness to REM sleep. Basically instead of going through the early stages and gradually falling into a deep sleep, you just suddenly go from being awake to being in a deep sleep.

kamilia20  FA2020 P497(Sleep physiology): Changes in narcolepsy: decrease REM latency.
... charcot_bouchard made a comment on nbme20/block1/q#6 (A 16-year-old student has uncontrollable sleepiness,...)
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submitted by charcot_bouchard(178)

Narcolepsy has one of the following 3 chraracter - 1. Cataplexy 2. dec orexin in csf 3. REM latency <15 min

its ass with (not dx criteria( Hypnagogin/pompic hallcination. Sleep paralysis

charcot_bouchard  oh dx criteria must also include excessive daytime slepeiness for 3 time per week over 3 month
... hayayah made a comment on nbme20/block1/q#7 (A 5-year-old girl with AIDS develops a progressive...)
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submitted by hayayah(603)

Acyclovir, famciclovir, valacyclovir are guanosine analogs. They undergo conversion to acyclovir monophosphate via virus encoded thymidine-kinase. Ultimately, they inhibit viral DNA polymerase by chain termination.

Mutated viral thymidine kinase can cause resistance.

... hayayah made a comment on nbme20/block1/q#8 (A 10-year-old girl is brought to the physician by...)
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submitted by hayayah(603)

Earliest detectable secondary sexual characteristic is breast bud development in girls, testicular enlargement in boys.

pg32  How did you know this? The Tanner stages in FA simply list pubarche and breast buds developing in the same stage without stating which comes first. Thanks!
lynn  @pg32 look at the paragraph above the diagram, it says that exactly. Took me a minute too lol
... hellohello made a comment on nbme20/block1/q#8 (A 10-year-old girl is brought to the physician by...)
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submitted by hellohello(0)

Found these notes written into my FA, unknown where they came from but has gotten me questions correct thus far.

Males: Testicular growth -> Penile Growth -> Pubarche -> Growth Spurt -> Spermatogenesis

Females: Thelarche -> Pubarche -> growth spurt -> Menarche

... lilyo made a comment on nbme20/block1/q#8 (A 10-year-old girl is brought to the physician by...)
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submitted by lilyo(18)

Take a look at FA pg.623 for tanner stages of sexual development.

... strugglebus made a comment on nbme20/block1/q#9 (A 50-year-old man is brought to the physician by his...)
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submitted by strugglebus(96)

Fronto-temporal dementia characterized by personality change is usually Picks

... hayayah made a comment on nbme20/block1/q#9 (A 50-year-old man is brought to the physician by his...)
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submitted by hayayah(603)

Frontotemporal dementia (formerly known as Pick disease): Early changes in personality and behavior (behavioral variant), or aphasia (primary progressive aphasia). May have associated movement disorders (eg, parkinsonism).

While this presents very similiarly to Hungtington's, you can differentiate it because in this stem it says "atrophy of the frontal lobes bilaterally" whereas Huntington's has atrophy of caudate and putamen with ex vacuo ventriculomegaly.

dickass  and the patient has no chorea
... thecatguy made a comment on nbme20/block1/q#9 (A 50-year-old man is brought to the physician by his...)
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submitted by thecatguy(4)

Classic NBME BS:

  • C gives the dated term with the contemporary term in parentheses
  • E only gives the dated term

So the examiner is acknowledging that they're not just living in the past, but they're also just a straight up a-hole

... hayayah made a comment on nbme20/block1/q#10 (A 77-year-old woman has been having difficulty...)
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submitted by hayayah(603)

Little finger = ulnar nerve.

C8-T1 are the roots of the ulnar nerve, which is a branch of the medial cord. The ulnar nerve is not found in the carpal tunnel (the medial nerve is).

Ulnar n. damage can lead to loss of wrist flexion and adduction, flexion of medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles. Loss of sensation over medial 1 1/2 fingers, including hypothenar eminence.

sugaplum  Also to add: since it is a bilateral sx it is more likely to be coming from the spinal cord then from equal compression of ulnar nerve (in guyons canal) on both sides. unless she is a cyclist
thefoggymist  shouldn't the other nerves of the same roots be affected?
thefoggymist  shouldn't the other nerves of the same roots be affected?
charcot_bouchard  Not really. In klumpeke paralysis ulnar nerve s/s dominates (Almost same cause)
... monoloco made a comment on nbme20/block1/q#11 (The sequence surrounding the first two exons of the...)
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submitted by monoloco(85)

This has to do with intron splicing. Remember GTAG. This mutation induced an AG closer where it was supposed to be, so some of that intron just became an exon.

... drdoom made a comment on nbme20/block1/q#11 (The sequence surrounding the first two exons of the...)
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submitted by drdoom(370)

As described in the question stem, this mutation occurs within an intron (a gene segment which is transcribed [DNA->RNA] but not translated). RNA splicing enzyme(s) grab RNA and “loop it”; an intron is cut out and the exons on either side of the intron are adjoined, like this:

exon1—intron—exon2 => exon1—exon2

Typically, this splicing occurs at the very edges of the intron (what I denoted with the “—” character). But in our case, a mutation within the intron is causing RNA splicing enzyme to recognize a new site: the splicer cuts within the intron (instead of at the very edge, as it should). So, we get something that looks like this:

exon1—intr—exon2

That’s a totally different mRNA molecule, and it's going to make our β-globin protein look (and behave) awfully strange.

... onyx made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by onyx(24)

The mass described is in the posterior mediastinum (see images below). The thoracic duct is damaged “near the mass”, hence drainage of organs distal to that point will be affected. The images below should clarify.

... onyx made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by onyx(24)

Mediastinal relations.

... onyx made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by onyx(24)

Thoracic duct relations.

consuela_salon  This was the picture that I liked the most for this question. If you imagine that the injury is at the level of the left subclavian vein (LSV) and thoracic duct (TD) crossing each other, maybe it will help you realize that the left breast & left upper extremity bypass the injury. The right lung is drained by the right lymphatic duct, not the TD (see one of the links bellow). And the heart is where eventually all the drainage is going to end up to be pumped again (TD -> LSV -> SVC -> heart).
mbourne  To keep it simple, the Thoracic Duct drains lymph from the entire body EXCEPT for 3 structures: Right Upper Extremity Right Thoracic Cavity Right Side of Head and Neck These 3 areas are drained by the Right Lymphatic Duct which enters the Right Internal Jugular Vein
... onyx made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by onyx(24)

Thoracic duct relations.

... hayayah made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by hayayah(603)

The left upper extremity and breast are drained by the axillary lymph node. The kidney is drained by the thoracic duct. The heart has its own lymph system going on surrounding the heart.

... thomas made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
jointaccount  Left breast & L UE drained by axillary. With the remaining choices, R kidney is the only choice outside the territory of the right lymphatic duct
... divya made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
... consuela_salon made a comment on nbme20/block1/q#12 (72 yo woman with dysphagia)
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submitted by consuela_salon(8)

This was the picture that I liked the most for this question. If you imagine that the injury is at the level of the left subclavian vein (LSV) and thoracic duct (TD) crossing each other, maybe it will help you realize that the left breast & left upper extremity bypass the injury. The right lung is drained by the right lymphatic duct, not the TD (see one of the links bellow). And the heart is where eventually all the drainage is going to end up to be pumped again (TD -> LSV -> SVC -> heart).

consuela_salon  (I meant the picture posted by onyx)
... hayayah made a comment on nbme20/block1/q#13 (A 6-week-old girl is brought to the physician by her...)
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submitted by hayayah(603)

No abnormalities, only some vomiting, looks well w/ no failure to thrive. Most likely immature LES.

masonkingcobra  http://www.sedico.net/English/SedicoInformationCenter/Physicians/gerd_e.htm
... suku008 made a comment on nbme20/block1/q#13 (A 6-week-old girl is brought to the physician by her...)
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submitted by suku008(6)

It’s a common disease that impacts babies and children. GERD stands for gastro esophageal reflux disease. Dr. Viraine Weerasooriya, a pediatric gastroenterologist on the medical staff of Golisano Children’s Hospital of Southwest Florida, says infants are prone to having reflux until their gut matures at about 12 to 18 months. But GERD is more than just reflux. “What this implies is individuals who have problems with gastro contents that move up to the esophagus or into the mouth.

suku008  https://www.youtube.com/watch?v=DFcySw14rIo
... hayayah made a comment on nbme20/block1/q#14 (A 28-year-old man who is a migrant worker comes to...)
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submitted by hayayah(603)

Of all the options, psoas major is the only one that is really associated with the lumbar vertebrae.

Q. Lumborum involves the transverse process of L1 but Psoas Major originates from L1-L5

imnotarobotbut  QL is connected to L1-L5 vertebrae as well (https://en.wikipedia.org/wiki/Quadratus_lumborum_muscle)
... studentdo made a comment on nbme20/block1/q#14 (A 28-year-old man who is a migrant worker comes to...)
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submitted by studentdo(6)

The major motion of Psoas major is flexion of hip. This patient is held in "rigid extension", hence he does not want to flex. Psoas is the only muscle on this list that connects the lumbars to lower extremity "holds his right lower extremity"

myoclonictonicbionic  The qstem said "lower extremity in rigid extension" which made it sound like extension at the knee joint rather than at the hip. Confusing wording
... aj32803 made a comment on nbme20/block1/q#14 (A 28-year-old man who is a migrant worker comes to...)
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submitted by aj32803(1)

Uworld specifically says that Psoas abscess means the patient will prefer flexion to avoid stretching the muscle. That's why Psoas did not make sense to me since the patient preferred extension, which would be stretching out the muscle.

On the other hand it's right on the vertebra and it's associated with TB.

adong  it's confusing but i think b/c psoas acts to flex at the hip, staying completely flat would keep the muscle from being contracted. uworld is talking about the psoas test which would end up hyperextending the psoas muscle which would elicit pain (psoas test can also be done with active flexion against pressure which would explain the not wanting to flex).
kamilia20  First ideal to my mind is that:patient is a TB, TB prefer psoas
... hayayah made a comment on nbme20/block1/q#15 (A 30-year-old man who completed a successful course...)
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submitted by hayayah(603)

Definition of adjustment disorder:

Emotional symptoms (eg, anxiety, depression) that occur within 3 months of an identifiable psychosocial stressor (eg, divorce, illness) lasting < 6 months once the stressor has ended.

If symptoms persist > 6 months after stressor ends, it is GAD.

hello  Yep, and I think what we are supposed to take from this Q is: The only info. we have for this patient is that he ended chemo 2 months ago and has been calling the doctor a lot -- this is supposed to mean he has been calling a lot since ending chemo 2 months ago. His frequent calls starting after ending chemo and within 3 months of the stressor fits with the above-stated definition of "adjustment disorder" with anxiety. I stressor in this case could possibly be either the actual illness or the ending of chemo/treatment. It probably does not matter much in this case.
charcot_bouchard  I think doing uw done me wrong here. Adjustment disorder isnt diagnosed when symptom match another disorder --- it was like never a right answer. But ofc its right answer in nbme
maxillarythirdmolar  Just to add to that, the tingling in his fingers may seem like a distraction/it probably is. Likely has some relation to his Chemo.
... johnthurtjr made a comment on nbme20/block1/q#15 (A 30-year-old man who completed a successful course...)
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submitted by johnthurtjr(81)

While I can get on board with Adjustment Disorder, I don't see how this answer is any better than Somatic Symptom Disorder. From FA:

Variety of bodily complaints lasting months to years associated with excessive, persistent thoughts and anxiety about symptoms. May co-appear with illness.

SSD belongs in a group of disorders characterized by physical symptoms causing significant distress and impairment.

savdaddy  I think part of it stems from the fact that this patients symptoms are occurring within the time-frame for adjustment disorder while SSD seems to have a longer timeline. Aside from that I find it difficult to see why SSD wasn't a possible answer.
chillqd  To add to that, I inferred that the obsession with checking temp and with the tingling sensation were signs provided to him by the physicians of recurrence. He is anxious over his cancer recurring, and they are more specific than a variety of body complaints
hello  In somatic symptom disorder, the motivation is unconscious. I think for the patient in this Q-stem, his motivation is conscious -- he wants to make sure that recurrence of cancer is not going "undetected".
cienfuegos  I also had issues differentiating these two and ultimately went with SSD, but upon further review it seems that a key differentiating feature was the timeline. His somatic symptoms would have had to have been present for at least 6 months per the DSM criteria https://www.ncbi.nlm.nih.gov/books/NBK519704/table/ch3.t31/
almondbreeze  @chillqd Same! Why not OCD? He's fearful that something bad might happen (=cancer relapse; obsession) and calling his doc (=compulsion)
... strugglebus made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by strugglebus(96)

The pons has nerves 5-8, so the trigeminal would be affected here

masonkingcobra  Thalamic pain syndrome would involve dysesthesias on the entire contralateral body so more than just the face. Also it occurs often after post-stroke. Additoinally, these dysesthesias appear weeks/months later
... whossayin made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by whossayin(7)

The mnemonic I like for remembering the locations of the cranial nerves is the "2,2,4,4 rule"

Above brainstem= CN I + II Midbrain= CN III, IV Pons= CN V, VI, VII, VIII Medulla= CN IX, X, XI, XII

... sympathetikey made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by sympathetikey(619)

Principle Sensory Nucleus of the Trigeminal is located in the Pons, as is the Motor Trigeminal Nucleus of the pons. This presentation is probably dealing more with the Principle Sensory Nucleus.

... chandlerbas made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by chandlerbas(42)

theres an association made in 2017 with trigeminal neuralgia and MS - which is what i think this pt has. key thing to note is that while all motor and sensory fibers of CN 5 enter at the level fo the pons (however some also do enter at the level of medulla and even the sc via the spinal tract of 5 to synapse with the long sensory nucleus of 5) heres the link of trigeminal neuralgia and MS: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5649347/

... lilyo made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by lilyo(18)

I was thinking along the lines of facial sensation which is mediated by the trigeminal nerve and the fact that the trigeminal nerve is located in the pons.

... feliperamirez made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by feliperamirez(4)

I do understand that the principal nucleus of the trigeminal nerve is located at the pons. But since this patient is having trigeminal neuralgia wouldn't you be disrupting the pathway involved in pain and temperature, which in this case would be the spinal nucleus (located in the medulla)?

Besides, I found this at an article

A recent hypothesis attributes the pain of trigeminal neuralgia to a central mechanism involving the pars oralis of the spinal trigeminal nucleus.[5]

https://www.ncbi.nlm.nih.gov/books/NBK539729/

pg32  I literally had medulla selected the whole time and then changed it to pons simply because i felt the test writers were just seeing if we knew where the trigeminal nerve was located. bummer because I think your logic is way better. it's what i first thought when i read the case.
... woodenspooninmymouth made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by woodenspooninmymouth(2)

MS is a demyelinating disease. That's why I didn't pick cortex or thalamus; they are grey matter. I picked medulla because I the spinotrigeminal nerves traverse the medulla. I guess we are just supposed to assume the demyelination is happening in the pons? I don't know.

woodenspooninmymouth  Sorry, I meant to say that the pons would have the cell bodies for the pain/temp neurons, no?
... thecatguy made a comment on nbme20/block1/q#16 (A 30-year-old woman with multiple sclerosis comes to...)
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submitted by thecatguy(4)

This is a very nitpicky question. As I see it, the 3 main concepts tested are:

  • This patient has trigeminal neuralgia (sharp, brief, episodic pain in the face), which is caused by a lesion to primary sensory fibers that carry pain sensation from the face.
  • Multiple sclerosis, which the patient has, is a demyelinating disease (i.e., it affects white matter).
  • The myelinated axons carrying pain sensation from the ipsilateral face enter the brainstem at the level of the pons and then descend (become the spinal tract of the trigeminal). These white matter fibers pass through the pons to synapse on the spinal nucleus of the trigeminal, which is in the medulla (nucleus = gray matter). (picture here). Therefore, a lesion in the white matter (i.e., plaque) in the pons could cause trigeminal neuralgia, and this phenomenon has been observed.

Above the level of the brainstem (thalamus & cerebral cortex), you have second order sensory neurons. Lesions in this part of the circuit are not generally in trigeminal neuralgia. I suppose they also want us to assume that once the spinal tract of the trigeminal enters the medulla, it's not myelinated anymore. I don't think this is completely true, but given the logic described above, pons would still be the better answer.

As people have pointed out, the primary sensory fibers carrying light touch sensation from the face synapse on the chief sensory nucleus in the pons immediately after they enter the pons. This question is not asking about those fibers though.

I got the question wrong too..

mightymito  Wow this is the best explanation yet! Thanks so much for very clearly walking us through a tricky question.
... strugglebus made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by strugglebus(96)

Nowhere have I been able to find why the hell this is a thing.

yotsubato  Its not in FA, Sketchy, or Pathoma, or U world. I knew it wasnt cancer because its bilateral. And Diabetes made no sense to me. So I just threw down Drug effect and walked away.
breis  same^^^
feliperamirez  The only possible explanation I think is that she was under a K sparing diuretic, such as spironolactone (which would lead to gynecomastia).
chandlerbas  you had me at its not in sketchy ;)
... strugglebus made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by strugglebus(96)

As an edit: 108,001 people reported to have side effects when taking Hydrochlorothiazide. Among them, 25 people (0.02%) have Breast discharge

neonem  I think the best way to answer this question was by process of elimination.
sympathetikey  That's some bullshit lol
karljeon  Haha I eliminated the answer by process of elimination.
medschul  I eliminated thiazides by process of elimination :(
medstudent65  Shit I eliminated thiazides because of elimination went with HTN thinking intercranial bleed effecting the pituitary
... niboonsh made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by niboonsh(173)

" Other classes of medications that cause hyperprolactinemia include antidepressants, antihypertensive agents, and drugs that increase bowel motility. Hyperprolactinemia caused by medications is commonly symptomatic, causing galactorrhea, menstrual disturbance, and impotence. It is Important to ensure that hyperprolactinemia in an Individual patient is due to medication and not to a structural lesion in the hypothalamic/pituitary area; this can be accomplished by (1) stopping the medication temporarily to determine whether prolactin levels return to normal, (2) switching to a medication that does not cause hyperprolactinemia "

https://www.ncbi.nlm.nih.gov/pubmed/16092584

"Non-dose-dependent side effects — Although low-dose therapy seems to minimize the metabolic complications induced by a thiazide or thiazide-like diuretic, it may not necessarily eliminate other side effects. As an example, as many as 25 percent of men treated with 25 mg/day of chlorthalidone develop a decline in sexual function [34]. Sleep disturbances can also occur, particularly if the patient is on a low-sodium diet [34]. How these problems occur is not known."

https://www.uptodate.com/contents/use-of-thiazide-diuretics-in-patients-with-primary-essential-hypertension#H2250530998

... namira made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by namira(16)

Possible explanation:

If the pt is taking a thiazide (which is K depleting), it might have also been given with a K sparing drug such as spirinolactone.

Spirinolactone has endocrinologic effects such as gynecomastia and galactorrhea.

sugaplum  I think you could only make this assumption if they said "patient is on standard htn tx" but since they gave the name hctz, would not be fair to assume they are also taking spirinolactone. I went with process of elimination on this one. Even checked access medicine's drug adverse effect profile...galactorrhea not listed for hctz
... hello made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by hello(144)

Goljan had a lecture that mentioned that "If a patient has galactorrhea, review every drug they're taking since many drugs cause galactorrhea."

The only thing of possible relevance in this Q-stem is that she takes a medication, therefore the answer of "drug effect" is the most likely reason for her galactorrhea.

... fkstpashls made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by fkstpashls(9)

Process of elimination is the only way to get this answer without Savant levels of autism, as some bowtie wearing doucher who wrote the question probably has.

Cancer is unilateral almost all the time, DM doesn't make sense for any reason, HTN itself wouldn't cause milky boobs, and mast cells degranulating doesn't make milky boobs either. So, and because many drugs can have milky boobs, you're left with drug effects by process of elimination.

djinn  I dont think the autor was a savant. Also I think is right proccess to think "cancer" can be bilateral and malignant but the "drug" that causes this isnt HCT. This question is bad written.
... sam1 made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by sam1(10)

Thiazides can cause acute interstitial nephritis, a form of renal failure. Without the renal excretion of prolactin, it can build up in the serum and result in galactorrhea.

coccidioinmytitties  Sexual dysfunction [desire based = libido] can be due to drug side effects [antihypertensives], per first aid. Edition: 2018 Page: 551 Section: Psych Per, 1stAid's endocrine section: "excessive amounts of prolactin associated with ↓libido [324]. This goes together with our sexual dysfunction with "antihypertensives." Only logical synthesis I can think of: thiazide = ↑prolactin = ↓libido + galactorrhea. It would also make sense since we are dealing with an expected to be post-menopausal female [milk production would have to be due to exogenous source]. Dug into my lecture notes and found the following: beta-blockers and thiazides cause sexual dysfunction. I also like sam1's explanation. We're reaching here, but its the best I can do.
g8427  Mayo clinic shows clear or bloody nipple discharge as side affect of Thiazides. But doesnt state milky discharge.
... minhphuongpnt07 made a comment on nbme20/block1/q#17 (A 50-year-old woman comes to the physician because...)
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submitted by minhphuongpnt07(4)

Thiazide=> hypercalcemia=> Oxytoxin (Gq coupled protein-> incr Ca2+)=> nipple discharge

... hayayah made a comment on nbme20/block1/q#18 (A 36-year-old man comes to the physician because he...)
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submitted by hayayah(603)

The tubes are catheters put in for urine to flow into a bag. So urine output is going to increase. The patient is also hyperkalemic. Aldosterone responds to hyperkalemia by increasing K+ excretion.

Hyperkalemia will stimulate aldosterone secretion even if renin is suppressed due to his hypertension. Although Na+ will be reabsorbed, this will be transient (should resolve once the potassium levels normalized) and since his urine output will most likely return to normal, his blood pressure should also normalize.

charcot_bouchard  Postobstructive diuresis Postobstructive diuresis is a polyuric state in which copious amounts of salt and water are eliminated after the relief of a urinary tract obstruction. The incidence of POD is unclear but estimates suggest 0.5% to 52% of patients will experience POD after relief of obstruction.10 It generally occurs after relieving BOO, bilateral ureteric obstruction, or unilateral ureteric obstruction in a solitary kidney.11 Diuresis is a normal physiologic response to help eliminate excess volume and solutes accumulated during the prolonged obstruction. In most patients, the diuresis will resolve once the kidneys normalize the volume and solute status and homeostasis is achieved. Some patients will continue to eliminate salt and water even after homeostasis has been reached, referred to as pathologic POD. These patients are at risk of severe dehydration, electrolyte imbalances, hypovolemic shock, and even death if fluid and electrolyte replacement is not initiated.9
... step1soon made a comment on nbme20/block1/q#18 (A 36-year-old man comes to the physician because he...)
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submitted by step1soon(24)

In postobstructive diuresis the Urine is usually hypotonic with large amounts of sodium chloride, potassium, phosphate and magnesium [3] Urine Output > 125 - 200mL/hour after relief of obstruction for at least 3 consecutive hours[4] Urine Osmolarity > 250mosm/kg [5]

https://wikem.org/wiki/Post-obstructive_diuresis

... hayayah made a comment on nbme20/block1/q#19 (A 60-year-old man comes to the physician because of...)
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submitted by hayayah(603)

This patient has small cell carcinoma. This type of cancer is associated with paraneoplastic syndromes such as: Cushing Syndrome, SIADH, or antibodies against Ca2+ channels (Lambert-Eaton) or neurons. Amplification of myc oncogenes is also common.

SIADH (Syndrome of inappropriate antidiuretic hormone secretion) is characterized by:

  • Excessive free water retention
  • Euvolemic hyponatremia with continued urinary Na+ excretion
  • Urine osmolality > serum osmolality

Body responds to water retention with aldosterone and ANP and BNP. That is what causes the increased urinary Na+ secretion Žwhich leads to normalization of extracellular fluid volume Žand the euvolemic hyponatremia.

hello  Why would body respond to water retention with ALDO? ALDO would increase water retention...
nala_ula  @hello, the body's response is to decrease Aldosterone since there is increased volume retention and subsequently increased blood pressure. This concept confused me a lot, but I ended up just viewing it as separate responses. First, the increased volume retention leads to increase ANP and BNP secretion that lead to decreased Na+ reabsorption in the tubules (page 294 in FA 2019) and second, this increased volume basically leads to increased pressure so lets also decrease aldosterone so there is no Na+ retention (since water comes with it)... I thought it was counterintuitive to secrete so much Na+ since you're already having decreased serum osmolality (decreased Na+ concentration) because of the water retention, but I'm guessing that this is just another way our body's well intentions end up making us worse XD
compasses  see page 344 FA2019 for SIADH.
dickass  author pasted text straight from FA but the arrows didn't copy over, inverting the original meaning
medninja  The idea of increasing urine Na is getting rid of water, thats why this mechanism end increasing urine Na secretion even when there are very low serum Na levels.
... dickass made a comment on nbme20/block1/q#19 (A 60-year-old man comes to the physician because of...)
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submitted by dickass(32)

SIADH: + Excessive free water retention + Euvolemic hyponatremia with continued urinary Na excretion + Urine osmolality > serum osmolality

Body responds to water retention with DECREASED aldosterone and INCREASED ANP and BNP

Water retention => Less aldosterone => Less ENAC channels => Less sodium reuptake => Loss of sodium in urine

... hayayah made a comment on nbme20/block1/q#20 (An 8-year-old boy is evaluated for ventricular...)
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submitted by hayayah(603)

Coarctation of the aorta leads to increased LV overload causing LV hypertrophy and a L axis deviation.

... hayayah made a comment on nbme20/block1/q#21 (A 75-year-old woman comes to the physician because...)
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submitted by hayayah(603)

This is an example of Shingles. Herpes simplex and herpes zoster viruses cause abnormal cell division in epidermal cells, and this creates multinucleated giant cells.

A Tzank smear showing multinucleated giant cells is characteristic of Varicella Zoster Virus infections. (HSV will have similar findings).

ergogenic22  other identifying terms for herpes: Single dermatome (does not cross the midline), painful (burning and itching),and lesions in multiple stages.
redvelvet  and why neutrophile infiltration, is it a thing? or just a distracting thing?
charcot_bouchard  Neutrophil comes into party always first. but it was distracting for me too.
dulxy071  Regardless if it can help resolve the issue, neutrophil will always be the first responder
... hmorela made a comment on nbme20/block1/q#22 (A 38-year-old woman comes to the physician because...)
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submitted by hmorela(9)

Why is it that the answer isn't also glossopharyngeal since you test CN IX by saying "Ah" also? Please help! Thanks!!

sinforslide  I believe that the arrow pointed to the uvula; uvular deviation would be testing for CN X palsy. CN IX's only motor innervation is the stylopharyngeus. (Not testing for gag reflex!)
... toxoplasmabartonella made a comment on nbme20/block1/q#22 (A 38-year-old woman comes to the physician because...)
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submitted by toxoplasmabartonella(7)

CN X carries efferent to palate. CN IX carries afferent from palate.

... hayayah made a comment on nbme20/block1/q#23 (A 34-year-old man who is HIV positive is brought to...)
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submitted by hayayah(603)

Mycobacterium avium complex infections are a common opportunistic infection in patients with advanced AIDS (CD4 count <50).

realfakedreams  @hayayah you were being lazy.. smh.. Homie started anti-retroviral therapy. HIV infects CD4 T-Cells through either CCR5 or more commonly CXCR4. Because of anti-retrovirals start working, HIV isnt able to infect anymore CD4 T cells. Thus CD4 t lymphocytes levels start to rise and are able to active B cells.
myf1991  Why can't it be monocyte? macrophage eat MAC and interact with CD4
... sympathetikey made a comment on nbme20/block1/q#23 (A 34-year-old man who is HIV positive is brought to...)
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submitted by sympathetikey(619)

CD4+ cells activate B-cells which form follicles and cause enlargement of lymph nodes. Therefore, in an AIDS patient, to enlarge the lymph nodes, the CD4+ dysfunction must be resolved.

breis  Yea i get that, but if the patients CD4 was ~35, how in the world did the CD4 count rise enough to stimulate B cell proliferation...? I don't get it
namira  The only thing i can think of is that: the cd4 count that is given was taken prior to having started the antiretroviral therapy. Since the question asks about "improved function", maybe its referring to the therapy actually being effective and its managed to increase cd4 count and function so as to be able to contribute to lymph node enlargement due to myco. avium
kamilia20  I though it transfer to a lymphoma,OMG
... strugglebus made a comment on nbme20/block1/q#24 (A 50-year-old man comes to the physician because of...)
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submitted by strugglebus(96)

This a CYP 450 inhibitor (SICKFACES.COM); its the O.

coccidioinmytitties  Azoles, as a class, are CYP450 inhibitors [fungal > human; to prevent conversion of lanosterol to ergosterol]. Justget is correct- a ↓pH is needed for absorption and PPI/H2RA/antacids are contraindicated.
... hayayah made a comment on nbme20/block1/q#24 (A 50-year-old man comes to the physician because of...)
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submitted by hayayah(603)

Add on to the other comment: SICKFACES.COM (when I Am drinking Grapefruit juice) is the mnemonic for remembering the CYP450 Inhibitors:

  • S odium valproate
  • I soniazid
  • C imetidine
  • K etoconazole
  • F luconazole
  • A cute alcohol abuse
  • C hloramphenicol
  • E rythromycin/clarithromycin
  • S ulfonamides
  • C iprofloxacin
  • O meprazole
  • M etronidazole

  • A miodarone

  • Grapefruit juice
charcot_bouchard  Its not a cytochrome question. IK because i go t it wrong
... justgettinby made a comment on nbme20/block1/q#24 (A 50-year-old man comes to the physician because of...)
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submitted by justgettinby(16)

Itraconazole requires the acidic environment of the stomach to be absorbed. Omeprazole inhibits the H+/K+ pump of the stomach, thereby decreasing the acidity of the stomach. So when the patient takes Omeprazole and Itraconazole together, Itraconazole won't be absorbed into the body. That's why it has no effect.

It's recommended to take medications at least 2 hours prior to taking an antacid.

necrotizingfasciitis  Just adding support to the above explanation: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671798/
pakimd  do all azoles or just itraconazole only requires an acidic environment to be absorbed?
chandlerbas  just itraconazole and posaconazole
lilyo  @chandlerbas, where did you find this information? I was looking over this on FA but they do not mention it and I would like a bit more information. Thanks!
chandlerbas  haha no stress! the article above submitted by @necrotizingfasciitis does a descent job explaining it, however its not good enough, I looked into a bit more on uptodate but wasn't fruitful in my endeavours. goodluck!
haozhier  How are we supposed to know this!! It is not in UWORLD or FA right?
... hayayah made a comment on nbme20/block1/q#25 (A 25-year-old primigravid woman at 42 weeks’...)
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submitted by hayayah(603)

Oxytocin uses IP3 signaling pathway.

GnRH, Oxytocin, ADH (V1-receptor), TRH, Histamine (H1-receptor), Angiotensin II, Gastrin.

FA mnemonic: "GOAT HAG"

dickass  I figured "if Oxytocin can cause milk secretion and enough uterine contractions to expel a full baby, it's probably activating smooth muscle contraction through Gq coupled second messengers"
... strugglebus made a comment on nbme20/block1/q#26 (Serum cholesterol concentrations are measured as...)
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submitted by strugglebus(96)

So you know that 65% of the data will fall within 1SD of the mean. So if you subtract 100-65 you will get 35. Which means that about 16% will fall above and 16% will fall below 1 SD. They are asking for how many will fall above 1 SD. I'm sure there is a better way of doing this, but thats how I got it lol.

sympathetikey  Except according to FA, it's 68% within 1 SD, so 34%, which split in half is 17%.
amirmullick3  Sympathetikey check your math :D 100-68 is 32 not 34, and half of 32 is 16 :)
lilyo  Can anyone explain why we subtract 68 from 100? This makes me think that we are saying its 35% of the data that falls within 1SD as opposed to 65. HELLLLLLP
sallz  @Lilyo If you consider 1 SD, that includes 68% of the population (in this case, you're saying that 68% of the people are between 296 and 196 (1SD above and 1 below). This leaves how many people? 32% outside of that range (100-68=32); half of those would be above 296 and the other half below 296, so 16%
... smpate made a comment on nbme20/block1/q#26 (Serum cholesterol concentrations are measured as...)
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submitted by smpate(5)

To get this one right, you would have to know that one standard deviation away from the mean on a bell curve is 34% on either side. After that it would be another 13.5% (but memorizing that is low yield). Looking at the specified age group, we want to know how much is greater than the mean plus 1 standard deviation. Therefore, 50% (the mean) plus 34% (1 standard deviation) is 84%. The rest is 100-84 = 16.

I found this image online for clarity

http://www.mathandstatistics.com/wp-content/uploads/2014/06/Example1EmpiricalGraphNormal.jpg

... monoloco made a comment on nbme20/block1/q#27 (A 53-year-old woman comes to the physician because...)
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submitted by monoloco(85)

When you have a traveler who has intermittent abdominal symptoms and diarrhea, and who has traveled to the likes of northern Africa and such, Schistosomiasis needs to be on your radar. At least, that’s how I’ve incorporated this nugget into my mental space.

... strugglebus made a comment on nbme20/block1/q#27 (A 53-year-old woman comes to the physician because...)
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submitted by strugglebus(96)

It also looked exactly like schistosome on the slide--it had the little spine. Entamoeba would have had a bunch of RBCs inside.

... usmleaspirant5 made a comment on nbme20/block1/q#27 (A 53-year-old woman comes to the physician because...)
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submitted by usmleaspirant5(1)

Schistosoma has spines whereas Giardia doesnt have a spine

... hellohello made a comment on nbme20/block1/q#27 (A 53-year-old woman comes to the physician because...)
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submitted by hellohello(0)

Schistosoma mansoni and haematobium can be ID'd by their unique spines. S. mansoni has a lateral spine as seen on the path while S. haematobium has a terminal spine (S. japonicum has no spine).

See following for path comparisons (mansoni L, haematobium M, japonicum R)

https://www.yourgenome.org/sites/default/files/images/photos/Schistosome%20eggs.jpg

... hayayah made a comment on nbme20/block1/q#28 (A previously healthy 16-year-old girl comes to the...)
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submitted by hayayah(603)

Trichomonas:

Clinical findings: thin, yellow-green, malodorous, frothy discharge and vaginal inflammation / itching.

Lab findings: pH >4.5 and motile trichomonads.

... strugglebus made a comment on nbme20/block1/q#29 (During an experiment, an investigator isolates an...)
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submitted by strugglebus(96)

Lysine is used in elastin and collagen cross linking; it is cross linked by lysyl oxidase to make collagen fibers

charcot_bouchard  Thats my brother from UFAP mother
smpate  but glycine and proline are used in elastin too. Seems like you'd have to know about desmosine though that's not in first aid. Or maybe you can infer lysine since it's charged and is probably more important in maintaining stability?
adong  the only thing we know about cross-linking is with LYSYL oxidase, hence lysine
... notadoctor made a comment on nbme20/block1/q#29 (During an experiment, an investigator isolates an...)
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submitted by notadoctor(106)

Analysis of the elastin in the question showed a decreased number of desmosine cross-links. Desmosine is made up of four lysine residues. Therefore abnormal elastin is likely missing lysine necessary for the formation of these desmosine cross-links. Wikipedia article on Desmosine.

dbg  how can i trust you, you aint even a doctor
euchromatin69  trust this then U.W 1249
tryntofigritout  UW 1249 was perfect. #loveyourname euchromatin ha
... hayayah made a comment on nbme20/block1/q#30 (A 33-year-old woman comes to the emergency...)
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submitted by hayayah(603)

Capitate and lunate are in the center of the palm. Capitate is not an option, so lunate is the answer.

Dislocation of lunate may cause acute carpal tunnel syndrome.

yotsubato  Lunate is the only carpal bone that is frequently dislocated. Scaphoid is frequently fractured. Hook of hamate is also frequently fractured.
redvelvet  and also point tenderness in the anatomical snuffbox may indicate a scaphoid fracture.
chandlerbas  yes lunate is the most common dislunated carpal bone ;)
almondbreeze  FA 2019 pg. 439 : dislocation of lunate may cause acute carpal tunnel syndrome
... hungrybox made a comment on nbme20/block1/q#30 (A 33-year-old woman comes to the emergency...)
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submitted by hungrybox(433)

Here's my approach (downvote if wrong):

falling on outstretched arm → usually scaphoid

BUT

scaphoid problem → pain in anatomical snuffbox

so then it goes to the next most commonly injured bone when you fall on an outstretched arm, your lunate

(which is right next to the scaphoid)