A 14-year-old girl is brought for evaluation because she has never had a menstrual period and has no breast development. Her mother notes she cannot smell coffee or perfumes. Examination shows prepubertal external genitalia. Serum FSH is 1.2 IU/L, LH 0.8 IU/L, estradiol 10 pg/mL. MRI of the pituitary is normal. What is the most likely diagnosis?

• A Kallmann syndrome ✓
• B Turner syndrome
• C Constitutional delay of growth and puberty
• D Craniopharyngioma

Explanation

Absence of breast development by age 13 years defines delayed puberty. Low gonadotropins point to a hypogonadotropic cause, and anosmia is pathognomonic of Kallmann syndrome, caused by failed migration of GnRH neurons along olfactory axons. Constitutional delay is the commonest cause of delayed puberty but preserves smell, and Turner syndrome produces high rather than low FSH. C normal pituitary MRI argues against a craniopharyngioma.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.