A 24-year-old woman presents with secondary amenorrhoea of 8 months. She has never been pregnant. Pregnancy test is negative. FSH is 95 IU/L, LH is 88 IU/L, and oestradiol is <20 pg/mL. Which additional test most specifically confirms the most likely diagnosis?

• A Serum prolactin
• B Karyotype (chromosomal analysis) ✓
• C Anti-Müllerian hormone (AMH) and antral follicle count
• D MRI pituitary gland

Explanation

High FSH and LH with low oestradiol in a young woman indicates hypergonadotrophic hypogonadism (premature ovarian insufficiency, POI). In women under 40 with POI, karyotype is essential to exclude Turner syndrome mosaic variants (45X/46XX) and fragile X premutation (FMR1). AMH and antral follicle count are already implied to be low in POI. Prolactin and pituitary MRI are appropriate for hypogonadotrophic (low FSH) amenorrhoea. Karyotype specifically characterises the aetiology in young POI.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.