A 22-year-old man presents with infertility, sparse facial hair, gynecomastia, and tall stature with disproportionately long limbs. Semen analysis shows azoospermia and buccal smear shows sex chromatin. The expected hormonal profile is:

• A Low FSH, low LH, high testosterone
• B Normal FSH and LH, low inhibin B
• C Low FSH, high LH, normal testosterone
• D High FSH, high LH, low testosterone ✓

Explanation

Klinefelter syndrome (47,XXY) produces primary testicular failure: seminiferous tubule dysgenesis causes azoospermia and loss of Sertoli cells, so FSH and LH rise from loss of negative feedback while Leydig cell insufficiency keeps testosterone low. The presence of sex chromatin (Barr body) distinguishes it from 45,X males. Testicular atrophy begins after puberty, explaining the delayed presentation with infertility and eunuchoid proportions.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.