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NBME 18 Answers

Block 1/Question#3
5 yo boy, history of motion sickness
Antagonist at muscarinic-3 receptors

Block 1/Question#10
25 yo woman, polycystic kidneys
HCO3: decreased; inorganic PO4: increased; parathryroid hormone: increased

Block 1/Question#11
67 yo man, fine resting tremor in both hands
Alpha-synuclein

Block 1/Question#13
10 yo boy, nosebleeds and easy bruising
Antibodies directed against the glycoprotein (Gp) IIb/IIIa complex

Block 1/Question#14
26 yo man with 27 yo wife, inability to conceive
Primary spermatocyte

Block 1/Question#15
experimental animal with defect in an innate gastrointestinal defence mechanism
Chronic gastritis

Block 1/Question#17
4 day old boy, vomited throughout night after breastfeeding
21-Hydroxylase

Block 1/Question#18
68 yo man, chronically increased hydrostatic pressure in Bowman space
Benign prostatic hyperplasia

Block 1/Question#19
70 yo woman, increasingly severe pain in right knee over 3 months
Pleomorphic neoplastic cells producing new woven bone

Block 1/Question#23
22 yo man, professional cyclist
Eccentric hypertrophy

Block 1/Question#26
50 yo woman, chronic obstructive pulmonary disease
Endothelial nitric oxide synthase production

Block 1/Question#28
Cholera toxin is a catalyst that results in the inhibition of GTPase activity of G-stimulator protein
Concentration of cAMP

Block 1/Question#30
29 yo woman irregular menstrual periods
Provide follow-up appointments to assess the patient's progress in attaining her goals

Block 1/Question#31
7 yo boy appendectomy
Low blood solubility

Block 1/Question#32
52 yo man with chest pain and shortness of breath
Proximal tubule: isotonic; Macula densa: hypotonic; Medullary collecting duct: hypertonic

Block 1/Question#33
35 yo woman with pain and swelling of breasts, pelvic discomfort
Have a chaperone join them for the remainder of the examination

Block 1/Question#34
60 yo man, 1 day of fever, chills, confusion and memory loss
Vibrio vulnificus

Block 1/Question#38
45 yo homeless man found unconscious
Methylmalonic Acid: normal; Homocysteine: increased

Block 1/Question#43
18 yo man cracked lips and sunburned skin
Barrier

Block 1/Question#44
26 yo man skiing accident
Axillary

Block 1/Question#45
55 yo man; father and brother died of myocardial infarct at early age
Increased transcription of HMG-CoA reductase

Block 1/Question#46
65 yo man, generalized tonic-clonic seizures
High-grade fibrillary astrocytoma

Block 2/Question#8
39 yo man, polycystic kidney disease
pH: 7.22; PCO2: 28; HCO2: 11

Block 2/Question#9
19 yo woman being treated for meningococcal meningitis
Adrenocorticotropic hormone stimulation test

Block 2/Question#15
38 yo man, 1 week history of shortness of breath with exertion
Aortic regurgitation

Block 2/Question#17
65 yo woman, 1 week of swollen, painful knee
Uric acid

Block 2/Question#18
Researcher testing new cancer drug
Neutrophil counts

Block 2/Question#21
66 yo woman, 2 days of fever, flank pain, pain with urination, nausea
Calcium carbonate

Block 2/Question#25
40 yo man, 1 year of orthostatic hypotension and loose stools
Motility disorder

Block 2/Question#27
58 yo man, 4 years of recurrent cough and sputum
Pseudostratified columnar epithelial cells

Block 2/Question#29
32 yo woman, new neurologic finding; imaging shows cavernous sinus thrombosis
Inability to abduct the eye

Block 2/Question#30
35 yo man, 4 weeks of severe midline back pain
ACTH

Block 2/Question#32
Investigator studying vancomycin-resistant Enterococcus faecalis
Plasmid loss

Block 2/Question#34
25 yo woman, fatigue for 3 weeks
Greening reaction on blood agar

Block 2/Question#37
34 yo man, semiconscious and combative
Pseudocholinesterase

Block 2/Question#41
35 yo woman, 3 days fever and sharp chest pain
Virus

Block 2/Question#44
35 yo woman, passed out while washing dishes
K+: decreased; HCO3: increased; Anion gap: normal; pH: increased

Block 3/Question#3
17 yo boy septic shock
alpha-1-Adrenoreceptors

Block 3/Question#5
82 yo woman, 24 hours of constant severe lower abdominal pain
Fibrin

Block 3/Question#6
32 yo woman, diagnosis of hyperparathyroidism
Abnormal migration of endoderm from the fourth pharyngeal pouch

Block 3/Question#9
35 yo woman with infertility
Spillage of contrast, which is normal

Block 3/Question#12
58 yo woman, 6 months shortness of breath, nonproductive cough
Pulmonary hypertension

Block 3/Question#13
35 yo woman, 2 days pain in left leg
Drug-related antibodies

Block 3/Question#14
2 yo boy, 2 days of fever, sore throat, rash
Erythrogenic toxin

Block 3/Question#17
46 yo woman, 1 week of fever and joint pain
Inflammatory infiltrates in the interstitium

Block 3/Question#21
48 yo woman, gradual onset of back pain over 2 weeks
Metastatic carcinoma of the breast

Block 3/Question#22
70 yo woman routine pelvic examination
Cystocele

Block 3/Question#25
63 yo man, 2 weeks of fullness in left upper quadrant of abdomen
Myelofibrosis

Block 3/Question#26
33 yo man, diagnosed with epilepsy
He is medically qualified to drive

Block 3/Question#31
28 yo woman, 4 days of palpitations, severe neck pain, fatigue, malaise
Subacute granulomatous thyroiditis

Block 3/Question#32
25 yo woman, 2 years of intermittent, diffuse, cramping lower abdominal pain
Accentuation of mu-opioid myenteric plexus receptor

Block 3/Question#33
4 yo boy, clumsy gait for 1 year
1/4

Block 3/Question#34
52 yo woman with breast cancer
Contraction

Block 3/Question#40
47 yo woman with irregular, raised, multicolored dark lesion
Subcutaneous tissue

Block 3/Question#41
24 yo man, 3 days of progressive numbness of both feet
Myelinated primary afferents

Block 3/Question#45
65 yo patient with lung region underventilated but well perfused
Physiologic shunt

Block 3/Question#46
45 yo man for annual health maintenance examination
Fenofibrate

Block 3/Question#47
19 yo woman, 2 days of pain in left index finger
Flexor digitorum profundus tendon

Block 3/Question#48
52 yo man, chronic pancreatitis
Colipase

Block 4/Question#3
68 yo man, 3 days of increasingly severe deep chest pain
Aortic aneurysm

Block 4/Question#4
36 yo woman, 2 weeks of fatigue, bleeding gums, bone pain
Histone acetylase

Block 4/Question#14
18 yo woman ingests 100 aspirin tablets in suicide attempt
pH: 7.32; PCO2: 15; HCO3: 8

Block 4/Question#15
45 yo man follows up 1 week after appendectomy
Gilbert syndrome

Block 4/Question#27
54 yo man, normal renal function, receives heart transplant
Cyclosporine

Block 4/Question#29
65 yo man, cancer of the cecum
Ileocolic → superior mesenteric → portal → right hepatic branch of the portal

Block 4/Question#30
5 yo girl, 1 day severe leg pain after falling off sled
Intestinal calcium absorption

Block 4/Question#31
57 yo man with alcoholism
Liquefaction

Block 4/Question#35
73 yo man, 4 months poor appetite and 25 pound weight loss
Cytokine effect

Block 4/Question#36
18 yo woman given general anesthesia for wisdom tooth extraction
Sarcoplasmic Ca2+ release

Block 4/Question#37
66 yo man, 1 month nonproductive cough, 6 months progressive shortness of breath
Idiopathic pulmonary fibrosis

Block 4/Question#42
4 month old boy, abnormal glycogen storage
alpha-1,4-Glucosidase

Block 4/Question#45
35 yo man, prolonged QT interval
Outward (delayed) rectifying potassium channel

Recent comments ...

... iguzman2 made a comment on nbme18/block1/q#3 (5 yo boy, history of motion sickness)
 +0  upvote downvote
submitted by iguzman2(0)

Aren't M1 receptors found in the brain and are responsible for motion sickness?

m-ice  M1 receptors are for sure the major muscarinic receptor type found in the CNS, but M3 receptors are the muscarinic subtype involved in vomiting controlled by the CNS. This is definitely a random fact, but I think they also wanted you to eliminate all other options. Targeting the sympathetic system (options A and B) won't make a difference. NMDA receptors are a major receptor throughout the CNS, but they're not a target of antihistamines, and neither are serotonin receptors. We know that antihistamines target histamine and muscarinic receptors, but the H2 histamine receptor is responsible for gastrin secretion in the stomach, so the answer must be antagonism of M3 receptors.
dorsal_vein  ^ First generation antihistamines definitely antagonize serotonin receptors within the CNS, which can cause weight gain and increase appetite. However, this plays little role in motion sickness.
... visualninjacontender made a comment on nbme18/block1/q#3 (5 yo boy, history of motion sickness)
 +0  upvote downvote
submitted by visualninjacontender(8)

https://onlinelibrary.wiley.com/doi/pdf/10.1111/cns.12468

pg.4 of the manuscript, bottom right paragraph

visualninjacontender  "As we know that all mAChR subtypes are expressed in the brain, while only M1, M2, and M5 exist in vestibular ganglia and vestibular end organs in humans [72]. The M1, M3, and M5 are postsynaptic excitatory receptors; M2 and M4 receptors are inhibitory. Furthermore, selective M3 and M5 antagonist zamifenacin was found to be as effective as scopolamine in preventing Motion Sickness. These lines of evidence suggest that scopolamine might exert its antagonistic effect on peripheral M1 and M5 and/or central M1 and M3 mAChR to prevent MS"
... cbrodo made a comment on nbme18/block1/q#10 (25 yo woman, polycystic kidneys)
 +0  upvote downvote
submitted by cbrodo(14)

Renal damage from PKD can ultimately cause chronic renal insufficiency. This impairs the ability of the kidney to excrete phosphorus and reabsorb HCO3. Elevated phosphate levels in the blood triggers release of FGF-23 from bone, which lowers vitamin D production and decreases calcium absorption in the intestine. The resulting hypocalcemia and hyperphosphatemia will lead to an increase in the secretion of PTH.

... match95 made a comment on nbme18/block1/q#13 (10 yo boy, nosebleeds and easy bruising)
 +0  upvote downvote
submitted by match95(6)

Immune thrombocytopenia (FA 2017, pg 405) - causes destruction of antibody-platelet complex by spleen leading to decrease in platelet QUANTITY and increased megakaryocytes on bone marrow biopsy.

... hayayah made a comment on nbme18/block1/q#14 (26 yo man with 27 yo wife, inability to conceive)
 +0  upvote downvote
submitted by hayayah(377)

Most problems with cell division occur in anaphase of Meiosis I.

realfakedreams  @hayayah - made an account just to say thank you. I appreciate that you exist.
... elasaf@post.bgu.ac.il made a comment on nbme18/block1/q#14 (26 yo man with 27 yo wife, inability to conceive)
 +1  upvote downvote
submitted by elasaf@post.bgu.ac.il(1)

Meiosis 1⇒ from primary to secondary spermatocyte ; Meiosis 2Secondary to spermatid

... sugaplum made a comment on nbme18/block1/q#15 (experimental animal with defect in an innate gastrointestinal defence mechanism)
 +0  upvote downvote
submitted by sugaplum(43)

FA 2019 Pg 373
chronic gastritis mucosal inflammation leading to atrophy

... t0pcheese made a comment on nbme18/block1/q#17 (4 day old boy, vomited throughout night after breastfeeding)
 +0  upvote downvote
submitted by t0pcheese(0)

why is the Na normal in this patient? Everything else made sense, the high K and 17 hydroxyprogesterone.

... breis made a comment on nbme18/block1/q#18 (68 yo man, chronically increased hydrostatic pressure in Bowman space)
 +0  upvote downvote
submitted by breis(9)

I put CHF, still not sure why it is wrong over BPH, but my reasoning is that BPH causes obstructive urine flow --> Hydronephrosis and once the urine has been made it can't be redone and is like filling up a damn with water. Straight Stasis. vs CHF there is protective mechanisms in place for a while until frank CKD.

... mahesh made a comment on nbme18/block1/q#19 (70 yo woman, increasingly severe pain in right knee over 3 months)
 +0  upvote downvote
submitted by mahesh(0)

Osteosarcoma histological appearance. Paget disease is one of risk factor

... elasaf@post.bgu.ac.il made a comment on nbme18/block1/q#26 (50 yo woman, chronic obstructive pulmonary disease)
 +0  upvote downvote
submitted by elasaf@post.bgu.ac.il(1)

Endothelin ==> vasoconstrictor of endothelial cells (makes ENDOTHELial cells go IN to the lumen --> vasoconstrictor)

... match95 made a comment on nbme18/block1/q#31 (7 yo boy appendectomy)
 +1  upvote downvote
submitted by match95(6)

Inhaled anesthetics that have low blood:gas partition coefficient/blood solubility dissolve in blood more easily. Therefore, there is LESS gas needed to saturate blood -- aka faster saturation of blood. This leads to faster saturation of brain.

tldr; low solubility --> faster onset --> faster recovery

... match95 made a comment on nbme18/block1/q#32 (52 yo man with chest pain and shortness of breath)
 +2  upvote downvote
submitted by match95(6)

This would just be the normal response of our kidneys to when we don't drink water enough (aka just normal).

Proximal tubule is isotonic because we are reabsorbing BOTH Na+ and H2O.

Macula densa is hypotonic because it is sensing the distal convoluted tubule -- the most DILUTE part of the nephron. Remember the countercurrent exchange system - thick ascending limb is losing NaCl (urine gets less concentrated as it ascends).

Medullary collecting duct is hypertonic because we are reabsorbing all the water making the urine more concentrated.

... sinforslide made a comment on nbme18/block1/q#34 (60 yo man, 1 day of fever, chills, confusion and memory loss)
 +0  upvote downvote
submitted by sinforslide(8)

The patient walked barefoot on the beach and had cirrhosis, which makes him vulnerable for V. vulnificus bacteremia. V. vulnificus bacteremia has a very poor prognosis.

From Uptodate: "[V. vulnificus] is the leading cause of shellfish-associated deaths in the United States. Infections due to V. vulnificus are most common in individuals who have chronic, underlying illness; individuals with liver disease or hemochromatosis are at greatest risk."

sinforslide  Also see UWORLD ID: 15255
... match95 made a comment on nbme18/block1/q#38 (45 yo homeless man found unconscious)
 +0  upvote downvote
submitted by match95(6)

Question was tricky -- need to look ate FOLATE levels. Both B12 deficiency and folate deficiency will cause an increase in homocysteine. Only B12 deficiency will cause an increase in BOTH methylmalonic acid AND homocysteine.

... famylife made a comment on nbme18/block1/q#45 (55 yo man; father and brother died of myocardial infarct at early age)
 +0  upvote downvote
submitted by famylife(34)

"Despite inhibition of HMG-CoA reductase by statins, cells compensate by increasing enzyme expression several fold. However, the total body cholesterol is reduced by 20%–40% due to increased expression of LDL receptors after statin administration."

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/hmg-coa

... letsdothis made a comment on nbme18/block2/q#8 (39 yo man, polycystic kidney disease)
 +1  upvote downvote
submitted by letsdothis(1)

Uremia: part of MUDPILE

hence you develop metabolic acidosis --> LOW bicarb with DEC. pH and you develop respiratory alkalosis in response

... chai_md made a comment on nbme18/block2/q#9 (19 yo woman being treated for meningococcal meningitis)
 +1  upvote downvote
submitted by chai_md(1)

Neisseria meningitides can lead to Waterhouse-Friderichsen syndrome (adrenal insufficiency, fever, DIC, shock)

... dorsal_vein made a comment on nbme18/block2/q#9 (19 yo woman being treated for meningococcal meningitis)
 +0  upvote downvote
submitted by dorsal_vein(2)
  1. Administer ACTH and monitor cortisol response
  2. If cortisol increases --> shock is due to pituitary insufficiency
  3. If cortisol does not increase --> shock is due to adrenal insufficiency

Dexamethasone suppression test is indicated for patients who present with signs of cortisol EXCESS.

... i-de-liver made a comment on nbme18/block2/q#17 (65 yo woman, 1 week of swollen, painful knee)
 +0  upvote downvote
submitted by i-de-liver(0)

Does anyone know why this is Uric Acid not N. gonorrhea? All I see in the micrograph are neutrophils. Is that white line in the middle of the picture that overlays the lymphocyte supposed to be the needle-shaped uric acid? Or is it because she's an old lady and usually septic Arthritis is from S. Aureus, so it would more like by uric acid and not gonorrhea since she's older?

maverick95  I struggled between those two answer choices as well. I thought that the large needle shape right in the middle was a uric acid crystal which helped push me towards Uric Acid as my answer. I also took into account that she was older (even though STIs are rampant among the elderly) she didn't really seem to have any other symptoms or history of STI/gonorrhea. I figured with her age that she just wasn't able to excrete Uric Acid enough, and got a gout. Something a pathologist told me one time was that they put the focus of the picture in the middle of the shot. So considering the uric acid-looking shape was right in the middle, I figured that's what they wanted us to focus on with the picture. Hope this helps.
i-de-liver  Ah gotcha! I guess I shouldn't have thought that the thing in the middle was an artifact lol... thank you!!
a1913  I believe it's because: 1) there is nothing given that would be risk factors for this woman to have N. gonorrhea 2) The thing in the middle is indeed an MSU crystal, just not under polarized light 3) apparently we get acute inflammation and increase in WBCs with crystal-induced arthropathies, per Table 11-2 on page 8 here (10 page document, top of page of interest will say p. 260) --> http://downloads.lww.com/wolterskluwer_vitalstream_com/sample-content/9781582558752_Mundt/samples/Chapter_11.pdf Also take a look at the pics on the previous page, left column for an example. I got this wrong as well, but I definitely won't again! lol
cr  i had the same problem, Whats about the fever?, could be present in gout?
... madmoroccan made a comment on nbme18/block2/q#21 (66 yo woman, 2 days of fever, flank pain, pain with urination, nausea)
 +0  upvote downvote
submitted by madmoroccan(0)

divalent cations interfere with the absorption (adsorbtion?) of Ciprofloxacin.

redvelvet  divalent cations interfere with the absorption of tetracyclines, not fluoroquinolones. anti-acids interfere with the absorption of fluoroquinolones. (like in this q, it's ca carbonate)
... sugaplum made a comment on nbme18/block2/q#25 (40 yo man, 1 year of orthostatic hypotension and loose stools)
 +0  upvote downvote
submitted by sugaplum(43)

https://www.ncbi.nlm.nih.gov/pubmed/7714464 common issues in type 1 and type 2 diabetics

... lae made a comment on nbme18/block2/q#27 (58 yo man, 4 years of recurrent cough and sputum)
 +0  upvote downvote
submitted by lae(0)

chronic bronchitis causes squamous metaplasia of the pseudostratified columnar epithelium in the bronchi and bronchioles

---- these columnar epithelium normally contribute to the mucociliary clearance and smoking also damages this clearance, so can get the clue from that too

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