A 30-year-old woman with primary amenorrhea and normal secondary sexual characteristics has serum FSH of 35 mIU/mL (high), estradiol below 20 pg/mL (low), and a normal 46,XX karyotype. Pelvic ultrasound shows a normal uterus and streak gonads. Which investigation is most useful to establish the etiology?

• A Serum anti-Müllerian hormone (AMH) level
• B Anti-ovarian (adrenal cortex) antibodies
• C Fragile X premutation (FMR1) testing ✓
• D Serum inhibin B level

Explanation

Premature ovarian insufficiency with 46,XX karyotype and normal uterus most commonly results from FMR1 premutation (fragile X carrier). It is the recommended first-line genetic test. Anti-ovarian antibodies are associated with autoimmune ovarian failure but are less common and not the primary screening test. AMH and inhibin B are low in POI but do not identify the cause.

Reference: Williams Gynecology, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.