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NBME 22 Answers

nbme22/Block 1/Question#32

A 17-year-old boy is brought to the emergency ...

Hypokalemia

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 +6  upvote downvote
submitted by liverdietrying(28),

Good fact to commit to memory: you lose bicarb in the stool (hence why diarrhea causes nonanion gap metabolic acidosis), and especially lose potassium with laxative abuse (as mentioned in the question stem). https://www.uptodate.com/contents/acid-base-and-electrolyte-abnormalities-with-diarrhea

sbryant6  I'm going to go take a big bicarbonate poop now. +4  
happysingh  i would suggest that you look into it a bit more. Why ? Had an nbme question (which confused the shit out of me) cuz, Bluemic Pt. who was abusing Laxatives (had the up & down arrows) and this is what it gave : Laxative Abuse — Metabolic Alkalosis :   ↓K+     ↑Cl-                   ↑pH    ↓HCO3- so one of the points of distinction IS the increase in Cl- with laxative abuse (vs. vomiting, which was a knee-jerk reaction when i hear bulimia) +  




 +5  upvote downvote
submitted by moloko270(31),

loss of fluid triggers aldosterone production, so patient will have hypernatremia and hypokalemia as a result





 +1  upvote downvote
submitted by iviax94(6),

I was between hypokalemia (due to diarrhea) and hypercalcemia/hyperuricemia (since sweat is hypotonic and would cause hyperosmotic volume contraction). I didn’t have a great way to decide between hyperCa/hyperuricemia so I figured they wanted hypoK. Is there a better rationale for why the hyper answers are incorrect?

liverdietrying  I think you over-thought this one a little bit with the hypercalcemia/hyperuricemia. Good fact to commit to memory: you lose bicarb in the stool (hence why diarrhea causes nonanion gap metabolic acidosis), and especially lose potassium with laxative abuse (as mentioned in the question stem). https://www.uptodate.com/contents/acid-base-and-electrolyte-abnormalities-with-diarrhea +1  
w7er  Basically they are asking about electrolyte distrubance that cause collapse mainly due to hypokalemia from laxative abuse because diarreha cause hypokamlemia and also cause incrase in renin angiotensin sytem which will further cause hypokalemia resuling cardiocascular colapse :) +  
hyperfukus  i thought the hyperuricemia thing too but i wasn't smart enough to think they wanted hypokalemia like u :( +  




 +0  upvote downvote
submitted by drmohandes(2),

You mostly lose HCO3- and K+ in stool.

Loss of HCO3- leads to a normal anion gap metabolic acidosis (FA2019 pg. 580 'HARDASS'), in which we also see a compensatory increase in Cl-.





one does not simply “walk into morder”