Get Care

Klinefelter syndrome

Klinefelter syndrome


  • Urology Health, American Urological Association.
  • European Association of Urology (EAU) guidelines on Sexual and Reproductive Health, 2022.

Klinefelter syndrome is a genetic condition where an extra chromosome (X) is present in the man (XXY, instead of XY). Klinefelter syndrome is the most common sex chromosomal abnormality. Adult men with Klinefelter syndrome usually have small firm testes along with features of low testosterone levels. In most cases, infertility and reduced testicular volume are the only clinical features that can be detected. Leydig cell function is also commonly impaired in men with Klinefelter syndrome and thus testosterone deficiency is more frequently observed than in the general population. Rarely, more pronounced signs and symptoms of low testosterone can be present, along with congenital abnormalities including heart and kidney problems.

Although the data are not unique, there is growing evidence that surgical sperm retrieval procedures (TESE or mTESE) yield higher sperm recovery rates when performed at a younger age.  Numerous healthy children have been born using IVF-ICSI without pre-implantation genetic diagnosis (PGD).


Regular medical follow-up of men with Klinefelter syndrome is recommended as testosterone therapy may be considered if testosterone levels are less than 300 ng/dL when fertility issues have been addressed. Since this syndrome is associated with several general health problems, appropriate medical follow-up is therefore advised.


Men with Klinefelter syndrome are at higher risk of metabolic and cardiovascular diseases (CVD), including venous thromboembolism (VTE). Therefore, men with Klinefelter syndrome should be made aware of this risk, particularly when starting testosterone therapy. In addition, a higher risk of haematological malignancies has been reported in men with Klinefelter syndrome.