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Physiology · Reproduction: gonadal dysgenesis
Sample itemA 15-year-old girl has short stature, webbed neck, no breast development and primary amenorrhoea. FSH and LH are markedly high and oestradiol is low. Which mechanism explains the high gonadotropins?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
C. Loss of ovarian follicles removes oestrogen and inhibin negative feedback on the pituitary
In Turner syndrome (45,X) oocytes undergo accelerated atresia, leaving streak ovaries. Without oestradiol and inhibin the pituitary is released from negative feedback, so FSH and LH rise. Oestrogen replacement induces puberty.
Option by option
A. Hyperprolactinaemia suppressing gonadotropins
Hyperprolactinaemia lowers, not raises, gonadotropins.
B. Hypothalamic GnRH deficiency
GnRH deficiency would give low gonadotropins.
C. Loss of ovarian follicles removes oestrogen and inhibin negative feedback on the pituitary (correct)
Correct. Absence of follicles removes negative feedback and raises FSH and LH.
D. Peripheral resistance to androgens
Androgen resistance occurs in 46,XY individuals and is not the cause here.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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