A 17-year-old girl presents with primary amenorrhoea. She is of normal height, has Tanner stage II breast development, and reports she has never been able to smell odours since childhood. MRI shows absent olfactory bulbs. Which finding is expected on hormonal evaluation?

• A Elevated FSH with low estradiol
• B Elevated LH with normal FSH
• C Normal FSH and LH with normal estradiol
• D Low FSH and LH with low estradiol ✓

Explanation

Kallmann syndrome is isolated GnRH deficiency with anosmia caused by failure of migration of GnRH neurons along olfactory axons, hence the absent olfactory bulbs. The defect is hypothalamic, so gonadotrophins (FSH and LH) are low or inappropriately normal with low estradiol, giving hypogonadotropic hypogonadism. Elevated FSH would indicate primary ovarian failure such as Turner syndrome, which also presents with short stature, distinguishing it from the normal height seen here.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.