Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
, 110 (20), 347-53

Klinefelter Syndrome: The Commonest Form of Hypogonadism, but Often Overlooked or Untreated

Affiliations
Review

Klinefelter Syndrome: The Commonest Form of Hypogonadism, but Often Overlooked or Untreated

Eberhard Nieschlag. Dtsch Arztebl Int.

Abstract

Background: Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. It causes hypogonadism and infertility. Until now, however, only about one-quarter of all persons with KS received the diagnosis during their lifetimes.

Methods: Selective review of the literature.

Results: KS is caused by aneuploidy of the sex chromosomes. Small, firm testes, the manifestations of androgen deficiency (sparse development of male-pattern body hair, greater than average height, lack of libido, erectile dysfunction) and, in more than 90% of affected men, azoospermia are its main features in adults. Affected boys may have verbalization difficulties and problems with learning and socialization. KS is often accompanied by other disturbances such as gynecomastia, varicose veins, thrombosis, osteoporosis, the metabolic syndrome, type 2 diabetes, and epilepsy. The most important therapeutic measure is testosterone supplementation, which should be initiated if the testosterone concentration drops below 12 nmol/L and should be given as directed in the guidelines for the treatment of hypogonadism. This recommendation is made even though there have not been any randomized controlled trials documenting the efficacy of testosterone therapy in adolescents or young adults. In some cases, viable sperm can be obtained from individual testicular tubules by biopsy, so that these patients are able to become fathers.

Conclusion: The diagnosis of KS would be less frequently missed if doctors were more aware of, and attentive to, its key manifestations, particularly the small, firm testes, erectile dysfunction, and the comorbidities mentioned above. If the diagnosis were made more often, patients would more often be able to receive early treatment, which would improve their quality of life.

Figures

Figure 1
Figure 1
Prevalence of type 2 diabetes mellitus (DM), impaired fasting glucose (IFG), or metabolic syndrome in 70 patients with Klinefelter syndrome and 70 age-matched controls (from [14]). Reproduced with the kind permission of John Wiley & Sons
Figure 2
Figure 2
Distribution of bilateral testicular volumes (both sides combined) in 160 patients with Klinefelter syndrome and 137 eugonadal men (modified according to [2])
Figure 3
Figure 3
FSH, LH, and testosterone levels in 228 patients with Klinefelter syndrome and 224 infertile men with normal karyotypes, with normal values shown in the background (blue fields). Boxes show interquartile range (IQR) with 5th and 95th percentiles. Continuous = median, broken lines = mean, solid circles = values not between 5th and 95th percentiles. Stars indicate significant differences (from [3]) LH: luteinizing hormone; FSH: follicle-stimulating hormone

Comment in

Similar articles

See all similar articles

Cited by 9 PubMed Central articles

See all "Cited by" articles
Feedback