A 20-year-old woman presents with primary amenorrhea and anosmia. She has Tanner stage 2 breast development and no pubic hair. Serum FSH is 2 IU/L, LH is 1.5 IU/L, and estradiol is 20 pg/mL. MRI shows absent olfactory bulbs. What is the most likely diagnosis?

• A Kallmann syndrome ✓
• B Turner syndrome
• C Androgen insensitivity syndrome
• D Mayer-Rokitansky-Kuster-Hauser syndrome

Explanation

Kallmann syndrome is hypogonadotropic hypogonadism (low FSH, LH, estradiol) with anosmia or hyposmia due to failed migration of GnRH neurons and olfactory bulbs during embryogenesis. The combination of primary amenorrhea, absent secondary sexual development, low gonadotropins, and anosmia is pathognomonic. Turner syndrome has elevated FSH. Androgen insensitivity has normal breast development with 46,XY karyotype. MRKH has normal hormones and normal olfactory function. (Ganong Review of Medical Physiology; Williams Endocrinology).

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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