Genetic and metabolic medicine
Klinefelter syndrome
47,XXY primary hypogonadism, how it presents in adults, the hormone pattern, testosterone replacement and PBS access, fertility by micro-TESE, and the metabolic, bone and cancer risks.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- 47,XXY, the commonest sex chromosome aneuploidy and the commonest genetic cause of primary hypogonadism and male infertility. About 1 in 600 males.
- Underdiagnosed: only about a quarter to a third are ever diagnosed, most as adults (median age in the 30s) during infertility or hypogonadism work-up.
- Key finding: small firm testes (under 4 mL) with azoospermia and high FSH and LH.
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Sources
- Zitzmann M, Aksglaede L, Corona G et al. European Academy of Andrology guidelines on Klinefelter syndrome. Andrology 2021;9:145-167European Academy of Andrology (endorsed by the European Society of Endocrinology), 2021
- Zitzmann M, Sansone A, Jannini EA et al. Recommendations for diagnosis and treatment of the aging male with Klinefelter syndrome. Aging Male 2025;28(1):2519035The Aging Male, 2025
- Klinefelter syndromeAU/NZHealthy Male (Andrology Australia)
- Testosterone: 24-month utilisation review (restriction text as at December 2019)AU/NZPBS Drug Utilisation Sub-Committee, 2020
- Pharmaceutical Benefits Scheme, testosterone (androgen deficiency restriction)AU/NZAustralian Government Department of Health, Disability and Ageing
- Yeap BB et al. Endocrine Society of Australia position statement on male hypogonadism (part 1). Med J Aust 2016;205:173-178AU/NZEndocrine Society of Australia, 2016
- Yeap BB et al. Endocrine Society of Australia position statement on male hypogonadism (part 2): treatment and therapeutic considerations. Med J Aust 2016;205AU/NZMedical Journal of Australia, 2016
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy