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OBG · Gynaecological endocrinology: secondary amenorrhoea
Sample itemA 22-year-old marathon runner with a BMI of 17 has had no periods for 8 months. Pregnancy test, TSH and prolactin are normal, and FSH, LH and oestradiol are low. What is the mechanism?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Reduced hypothalamic GnRH pulsatility
Low energy availability from exercise and low weight suppresses GnRH pulses, giving low gonadotropins and oestradiol (functional hypothalamic amenorrhoea). Management is weight gain and reduced exercise. Ovarian failure would raise FSH.
Option by option
A. Autoimmune destruction of ovarian follicles
Ovarian autoimmunity would raise FSH, not lower it.
B. Raised androgens from polycystic ovaries
Polycystic ovary syndrome shows normal or raised LH and androgen excess.
C. Intrauterine adhesions
Adhesions cause amenorrhoea with normal hormone levels.
D. Reduced hypothalamic GnRH pulsatility (correct)
Correct. Energy deficit suppresses GnRH pulses.
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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