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Discussion Starter #1
A 21 year old male presents with a scrotum that lacks palpable testes. On examination bilateral inguinal masses are observed. His secondary sexual characteristics are well developed & he denies any impairment in sexual drive or performance. Further evaluation reveals a very low sperm count. Which of the following is most likely to be decreased in this patient ?

A) GnRH
B) Inhibin
C) FSH
D) Testosterone
E) LH
 

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this person has cryptorchidism, and due to inc in abdominal temperature, there is destruction to sertoli cells and therefore inhibin will be low and there wont be any spermatogenesis and low sperm count but due to normal testo , patient has no dec libido...so the ans is B
 

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nope

its seems to be D ... and most probably he is patient of klinefelter syndrome ..mostly presents after 18 years ..
the question is directing towards cryptorchidism via insisting on bilateral inguinal masses, and there isn't anything that mentioned decrease in secondary sexual characters to suggest low test. add for that his good sexual life, so testosterone should be excluded first
 

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Ans.

B. Inhibin
Normal sexual characteristics exclude testosterone and LH deficiency. The sertoli cells are the most vulnerable cells to be damaged in cryptorchidism, (leydig cells which produce testosterone are more resistant), so sertoli cells can`t produce testosterone binding protein to stimulate spermatogenesis in seminiferous tubules, and also can't produce inhibin, which would not create a negative feedback on FSH . GnRH is not affected.
 

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the question is directing towards cryptorchidism via insisting on bilateral inguinal masses, and there isn't anything that mentioned decrease in secondary sexual characters to suggest low test. add for that his good sexual life, so testosterone should be excluded first
oops sorry i was feelin sleepy when i read this question lolxxxxxxxx yup its cryptorchidism and inhibin would b right answer .... inhibin would b decreased
 

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B) Inhibin
 

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haha..yeah i mean to say FSH is dec..
(because if inhibin is dec the FSH will inc and spermatogenesis will be inc,which is not the case here)
FSH will not be dec instead it will be increased because Fsh is secreted from the pitutary and inhibin is low cuz it is produced in sertoli cells and low inhibin causes inc of FSH!
 

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Discussion Starter #16
B) Inhibin

The correct answer is B) Inhibin

This patient has undescended testes, or cryptorchidism. The failure to completely descend may be unilateral or bilateral. The temperature inside the scrotal sac is lower than body temperature, creating an idea environment for seminiferous tubules (since they are temp sensitive & prone to heat induced damage). If undescended testes are not are not surgically moved to the scrotal sac, the seminiferous tubules become atrophic & hyalinized over time, resulting in a low sperm count. Also, because the seminiferous tubules are responsible for secretion of Inhibin, circulating levels of inhibin will be decreased. FSH levels will be elevated due to loss of negative inhibition by inhibin. The testosterone producing Ley-dig cells are not sesitive to temperature so Testosterone & LH levels are normal.
 
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