Which single laboratory finding best distinguishes premature ovarian insufficiency from functional hypothalamic amenorrhoea as a cause of secondary amenorrhoea?

• A Low serum estradiol
• B Elevated serum anti-Mullerian hormone
• C Low serum inhibin B
• D Elevated serum FSH on two occasions 4 to 6 weeks apart ✓

Explanation

Both conditions produce hypoestrogenic amenorrhoea, so estradiol alone cannot separate them. Premature ovarian insufficiency is defined by amenorrhoea before age 40 with elevated FSH (above 25 IU/L) on two occasions at least 4 weeks apart, reflecting ovarian resistance to gonadotropin drive. In hypothalamic amenorrhoea the entire axis is suppressed, so FSH is low. AMH is low in POI, not elevated.

Reference: Williams Gynecology, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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