A 51-year-old woman has amenorrhoea for 12 months with hot flushes. Her serum shows FSH 45 IU/L, LH 28 IU/L, and estradiol 12 pg/mL. The primary reason for the elevated gonadotrophins is:

• A Primary pituitary adenoma secreting FSH autonomously
• B Loss of negative feedback from ovarian estradiol and inhibin on the pituitary ✓
• C Increased hypothalamic GnRH pulse frequency independent of ovarian status
• D Reduced hepatic clearance of circulating gonadotrophins

Explanation

Menopause reflects exhaustion of the finite pool of ovarian follicles. With few follicles remaining, secretion of estradiol and inhibin falls sharply, removing negative feedback on the pituitary, so FSH rises more than LH. The postmenopausal ovary still produces some androgen from stromal cells, but estrogen comes mainly from peripheral aromatisation of adrenal androgens. B pituitary adenoma would be a diagnosis of exclusion and would not fit the low estradiol with typical climacteric symptoms, and altered clearance does not explain selective FSH elevation.

Reference: Williams Gynecology, 4th ed.

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Written and medically reviewed by the StethoPrep medical team.