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Klinefelter Syndrome — RACP Adult Medicine MCQ

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EasyEndocrinology & DiabetesKlinefelter SyndromeRACP Adult Medicine

A 50-year-old man presents with bilateral gynaecomastia and hypogonadism. He has small firm testes, tall stature, and wide arm span. His karyotype is 47,XXY. What is the diagnosis?

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Correct answer: AKlinefelter syndrome

Klinefelter syndrome (47,XXY) is the most common sex chromosome aneuploidy (1 in 660 males). Features include tall stature, small firm testes (due to seminiferous tubule dysgenesis), gynaecomastia, hypogonadism (low testosterone, high LH/FSH – primary), infertility (azoospermia), and eunuchoid body habitus. It is a common cause of primary hypogonadism in men. Management includes testosterone replacement therapy (improves energy, mood, bone density, sexual function) and fertility assessment (sperm retrieval with ICSI may be possible). Increased risk of breast cancer, osteoporosis, and metabolic syndrome.

Reference: eTG – 2025 – Endocrinology; Endocrine Society – 2018 – Klinefelter Guidelines