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Klinefelter syndrome: going beyond the diagnosis
  1. Gary Butler1,2,
  2. Umasuthan Srirangalingam3,
  3. Jennie Faithfull3,
  4. Philippa Sangster4,
  5. Senthil Senniappan5,
  6. Rod Mitchell6,7
  1. 1Paediatric and Adolescent Endocrinology, University College London Hospitals NHS Foundation Trust, London, UK
  2. 2UCL Great Ormond Street Institute of Child Health, London, UK
  3. 3Endocrinology, University College London Hospitals NHS Foundation Trust, London, UK
  4. 4Urology and Andrology, University College London Hospitals NHS Foundation Trust, London, UK
  5. 5Endocrinology, Alder Hey Children's NHS Foundation Trust, Liverpool, UK
  6. 6MRC Centre for Reproductive Health, University of Edinburgh Division of Reproductive and Developmental Sciences, Edinburgh, UK
  7. 7Department of Diabetes and Endocrinology, Royal Hospital for Sick Children, Edinburgh, UK
  1. Correspondence to Professor Gary Butler, Paediatric and Adolescent Endocrinology, University College London Hospitals NHS Foundation Trust, London NW1 2PG, UK; gary.butler{at}


Although Klinefelter syndrome (KS) is common, it is rarely recognised in childhood, sometimes being identified with speech or developmental delay or incidental antenatal diagnosis. The only regular feature is testicular dysfunction. Postnatal gonadotropin surge (mini-puberty) may be lower, but treatment with testosterone needs prospective studies. The onset of puberty is at the normal age and biochemical hypogonadism does not typically occur until late puberty. Testosterone supplementation can be considered then or earlier for clinical hypogonadism. The size at birth is normal, but growth acceleration is more rapid in early and mid-childhood, with adult height greater than mid-parental height. Extreme tall stature is unusual. The incidence of adolescent gynaecomastia (35.6%) is not increased compared with typically developing boys and can be reduced or resolved by testosterone supplementation, potentially preventing the need for surgery. Around two-thirds require speech and language therapy or developmental support and early institution of therapy is important. Provision of psychological support may be helpful in ameliorating these experiences and provide opportunities to develop strategies to recognise, process and express feelings and thoughts. Boys with KS are at increased risk of impairment in social cognition and less accurate perceptions of social emotional cues. The concept of likely fertility problems needs introduction alongside regular reviews of puberty and sexual function in adolescents. Although there is now greater success in harvesting sperm through techniques such as testicular sperm extraction, it is more successful in later than in early adolescence. In vitro maturation of germ cells is still experimental.

  • growth
  • child development
  • endocrinology
  • genetics
  • mental health

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  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; externally peer reviewed.