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Discussion in 'USMLE Step 1' started by orthopod, Mar 12, 2016.
Hi! New to posting here. But this question on NBME18 has also been driving me NUTS. I asked my endo professor about it who is brilliant.
She said the question stem does not give us enough info to determine a diagnosis. It's not kleinfelter's bc the kid is short, also in kleinfelter's you have high FSH, and this guy has low-normal FSH. Also not androgen insensitivity or testosterone would be super high, and in this guy it is low-normal again.
So basically this guy most likely had gynecomastia b/c of hyperprolactin. He could have a prolactinoma (which are actually pretty common apparently, and can be small and go undetected). The higher prolactin levels would negatively feedback on GnRH, less GnRH, less LH and FSH produced.... so that's why T and FSH are a low.
Also, another big cause of secondary hypogonadism is hypothyroidism. TRH actually stimulates prolactin secretion. So...low TSH, less neg feedback, high TRH. high TRH, stimulates prolactin.... prolactin feeds back on gnrh, less LH and FSH. This also fits with why the guy is short. Thyroid hormone is really important in long bone growth, just like E. In real life he prob would have had symptoms from the hypothyroid, but who knows, nothing is black and white. It's the only thing that fits for why he is really short.
And yeah, I agree, this f**king sucks, who would be able to know this on an exam? insane. But I think the moral of the story here is that most of these questions, we have to figure out thru process of elimination thru the answers given. Gynecomastia was the only one that made sense. But it wasn't because of T turning into E. The guy had low T, any extra T would not turn into estrogen and give him boobs...it would be used towards secondary sex characteristics. Also.. lowish FSH, means less aromatase being made to turn T to E. So that's not the cause of gynecomastia. in kleinfelter's they get gynecomastia b/c of the high FSH -> producing lots of aromatase to turn T->E.
Idk, this sucks ha. I am absolutely terrified for my exam this coming Sunday. My brain can't function this quickly to reason all this stuff out in 1 minute.
Also this might not even be right, bc hypothyroidism would be the 17 yr old would prob be overweight and stuff? It could be some crazy pathway with low IGF.
If anyone else figures it out let us know.
Basically impossible to know the correct diagnosis for this question. But, that's not the goal. The goal is arriving to the correct answer, by whatever means. POE will often be your best friend when taking Step. Good luck!
.NBME SAYS THAT ANSWER IS BLACK FLY BUT I THINK ITS TICK BITE..CAN ANYONE EXPLAIN?PLZ
Hi, literally just created an account to respond to this. I am so confused with this question.
My (wrong) answer was "Strong muscular development" because after much thought I realized that if could be a case of exogenous use of anabolic steroid in a male teen: this would lead to short stature, low FSH and low testosterone. I get that it's kind of a stretch, but it made more sense than any other answer.
As to why gynecomastia, def not Klinefelter or AIS. Maybe normal teen? I don't know.
NBME says this is black fly? Really?
Why not secondary hypogonadism? Or like 5-alpha reductase deficiency?
The answer is 100% tick. Probably has some bootleg key