A 14-year-old girl has not yet had any breast development or pubic hair (Tanner B1, PH1). Her height is at the 5th centile. FSH is markedly elevated (68 IU/L), LH elevated (35 IU/L), and estradiol is very low. Karyotype is 46,XX. Pelvic ultrasound shows a small uterus and streak gonads. The diagnosis is:

• A Hypogonadotropic hypogonadism (Kallmann syndrome)
• B Constitutional delay of puberty
• C Primary hypothyroidism causing delayed puberty
• D Hypergonadotropic hypogonadism — 46,XX gonadal dysgenesis ✓

Explanation

This presentation — complete pubertal failure (B1, PH1), markedly elevated FSH and LH (hypergonadotropic state), very low estradiol, streak gonads, and 46,XX karyotype — is diagnostic of 46,XX gonadal dysgenesis (Swyer syndrome variant or ovarian failure). The elevated gonadotropins reflect absent negative feedback from the non-functional gonads. Turner syndrome (45,X) would be the same endocrine picture but with a different karyotype. Hypogonadotropic hypogonadism has low/normal FSH and LH. Constitutional delay shows a delayed but eventually normal puberty with normal gonadotropin response. Hypothyroidism causes delayed puberty but not streak gonads or massively elevated gonadotropins.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.