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 +0  (nbme21#35)

this patient presents with hypochromic anemia, it cannot be hypomagnesemia because it doesnt cause anemia, cannot be B12 because it would be megaloblastic, cannot be vitamin D because its not related to hypochromic anemia, and zinc is associated with iron deficiency anemia, but as a deficiency. Also, lead poisoning inhibits ferrochetalase, it looks like an iron deficiency anemia but since theres no other logical option it has to be the answer here


Subcomments ...

submitted by rockediny(9),

Dextro is the correct answer here. From the choices given, dextro is the least likely to cause constipation since its main mechanism of action is NMDA antagonism w/some opioid activity -- it can cause constipation but the other choices are MUCH MORE likely to. As for diphenhydramine = it is not appropriate for elderly patients and it isn’t an antitussive.

forerofore  diphenhydramine and other Gen 1 antihistamines are good choices for chronic cough in allergy and patients with posterior draining and post viral chronic cough (careful with the elderly). That being said, apparently it also causes constipation, so dextro is still the correct answer. +1  

submitted by iviax94(7),

There have been a couple of questions about this topic on the newer exams. I’ve been answering by equating libido to testosterone levels and nocturnal erections to health of vasculature (atherosclerosis or not). Is this correct?

liverdietrying  When you’re thinking of libido, don’t just equate it to testosterone -- make sure you’re always considering depression! Depression following stroke is common, especially with residual physical disability, so this would decrease his libido. Nocturnal erections equate to “does it actually work?” not just the vasculature but the neural input as well. For example, during prostatectomy damage to the pelvic plexus (nerves) can lead to impotence. There’s nothing to suggest that he has vascular or neurologic erectile dysfunction here, which is why his nocturnal erections are intact. +11  
_pusheen_  @liverdietrying Was it premature to assume he has trouble with erections because of neural damage from the stroke? I put low libido, low nocturnal erections. Is it because the stroke resulted in hemiparesis and not autonomic dysfunction or something like that? +3  
liverdietrying  @pusheen Correct, you won’t classically get impotence after a hemiplegic stroke. His inability to achieve an erection is much more likely to be 2/2 psychosocial effects than organic disease. If this vignette instead said that this had gotten a prostatectomy with resulting damage to the pelvic nerves that allow for erection, then it’d be a more safe choice to put no nocturnal erections. +3  
fast44  Is there a video or somewhere that explains these sexual dysfunctions? This seems to be a topic that keeps repeating on the new exams. +1  
forerofore  well, i though that because he had a stroke he would be likely to have atherosclerosis, which would keep libido high and reduce nocturnal erections, i kinda ignored the whole "he´s depressed" part of the vignette despite understanding the mechanism well. but from a clinical depression point of view, if his arteries are intact, and he is depressed, then libido would be low, and erections present at night. +4  
pg32  I can't remember exactly but I swear the question on NBME 21 the guy's wife had died as well...? Or they had gotten divorced? Either way, he had some psychological baggage as well, but his libido was still normal, and the explanation was that his testosterone would be fine regardless of his depressed mood. So I went with that logic here and missed this question. I don't understand how I am supposed to gauge someone's libido based on vague hints at their mood, especially when in one exam mood does not decrease libido and in the other it does. +  
drzed  @pg32 bro spoilers +1  

submitted by medstudied(2),

Can someone please explain why the answer to this is injury to the posterior cord rather than the radial nerve?

pipter  because raising the arm above the shoulder suggests abduction which would mean the axillary nerve is also involved. the lesion would be more proximal. +6  
kchakhabar  I thought "up to the shoulder" is done by deltoid muscle (aka axillary nerve) and above is done by trapezius. +3  
forerofore  as far as i can find, abduction ranges of motion, per first aid are: 0-15° = supraspinatus 15-90° = Deltoid 90° = trapezius 100° (over the head) = serratus anterior in this question, they are directly telling you its not the serratus (long thoracic), because no option compromises it. Also, trapezius is innervated by cranial nerve XI, which is not a part of the brachial plexus, so, even though its worded weirdly, you can assume they are talking about deltoid disfunction. so deltoid disfunction (axillary) + radial disfunction = posterior cord +2  

submitted by pppro(14),

Yersinia thrives in cold temperatures and can be obtained from poor sanitated milk. (Check sketchy sketch)

forerofore  growth in cold temperatures seems to be the method of isolation of yersinia enterocolitica https://www.ncbi.nlm.nih.gov/pmc/articles/PMC275385/ https://jcm.asm.org/content/2/6/559 +  

submitted by lamhtu(55),

It appears that although NRTIs are phosphorylated by thymidine kinase, resistance is actually due to mutations in the actual reverse transcriptase rather than thymidine kinase itself.

forerofore  mutations in thymine kinase are more frequent in herpes drugs +2  
mtfp  NRTI need to be phosphorylated by HOST CELL thymidine kinase, mutation in viral kinase has no role in NRTI resistance +6  

submitted by pppro(14),

Patient has BPH. Give alpha one antagonist to reduce smooth muscle contraction and relieve difficulty urinating.

d_holles  lol i thought it was some kind of urinary retention problem and put H. +8  
sbryant6  How is H wrong? Oxybutinin or tolterodine treat urinary incontinence by blocking M3 muscarinic acetylcholine receptors --> urinary retention. We're just supposed to assume they are talking about BPH here because he is old? +  
jaxx  I agree. I picked "H" for that same logic. Does anyone know where we should have come to the conclusion that this was BPH? +  
forerofore  they are telling you he's having "difficulty urinating", one of the clinical criteria for BPH is reduced urinary flow rate. this is not incontinence because they are not telling you he leaks at all, just that he pees "a lot" +6  
drzed  Even if he was urinating too much, anticholinergics are contraindicated in the elderly (Beers criteria) +2  
pathogen7  @drzed tI mean techinically alpha-1 blockers are on the Criteria too ... +1  

submitted by seagull(714),

Examining patient from a urologist implies Berkson Bias which would skew the population mean of serum urea nitrogen away from the true accurate mean. Then, realize precision is dependent on statistical "Power" which is increased based on the size of the population of the study. (increased precision = increased statistical power). Therefore, an increase in population of a biased group with lead to inaccuracy with high precision.

forerofore  to add up, the urologist himself doesn't add or remove accuracy (since this is a blood test), what decreases the accuracy is the fact that in order to be sent to a urologist you probably are sick in the first place (selection bias), so your urea nitrogen is likely to be altered. +13  

submitted by neonem(366),

Major risk factor for aortic dissection is hypertension, and in this case might be due to cocaine use, which causes marked hypertension. Dissections cause a tear in the tunica intima -- blood can flow backwards into the pericardium and cause tamponade. This manifests as crackles in the lung due to poor left ventricular function (filling/diastolic problem due to compression).

forerofore  there is another clue, the man has diminished pulses in just one arm, which means that the left subclavian artery must be involved somehow, and an aortic dissection would be the best answer explaining this. +5  
temmy  please why is there where a diastolic mumur? +1  
whoissaad  @temmy Aortic dissection especially near the root of aorta can lead to dilatation of the aortic valves, which can lead to Aortic regurgitation (diastoic murmur at left sternal border) +6  
garibay92  Does anyone know why is this patient's tepmerature elevated? +1  
ratadecalle  @garibay92, not important for this question I think but cocaine can cause malignant hyperthermia +1  
almondbreeze  judging by his heart murmur, he probably has marfan syndrome. that's the only place where FA talks about dissecting aneurysm +  
almondbreeze  he's only 28 - another clue for marfan? +  
turtlepenlight  did anyone else think it was weird his only sx was SOB? I always think of radiating pain as being a good clue for dissection +1  
cmun777  @almondbreeze his heart murmur is at the LSB (aortic regurg) and not consistent with MVP plus no other sx/indication of Marfan. I think the only association of RF you should think about in this question is the cocaine use and consequent HTN. +1  
ibestalkinyo  @turtlepenlight I agree. I chose another answer because I was like, there's no way this guy doesn't hurt if he's got a dissection. +