Body composition, metabolic syndrome and type 2 diabetes in Klinefelter syndrome

Klinefelter syndrome (KS) affects 1:660 men, making it the most common sex-chromosome disorder in man, and is a common cause of infertility, hypogonadism and learning disability. Men with KS are described as tall, slim, narrow shouldered, broad hipped, with hypergonadotropic hypogonadism and small testes, and recently the description has been expanded to include increased risk of the metabolic syndrome, type 2 diabetes and an unfavourable change in body composition, with accumulation of body fat and decreased muscle mass and a concomitant decrease in insulin sensitivity, muscle strength and oxygen consumption capacity. Here, we review the data on body composition, bone turnover, liver function, insulin resistance and metabolic syndrome in relation to testosterone in both patients with KS and normal men. Treatment with testosterone in hypogonadal men (other than KS) improves body composition in both clinical and experimental studies. Despite the lack of such studies in KS, we recommend testosterone treatment to patients with KS with low serum testosterone or increased LH and change in body composition and thus possibly prevent common diseases like type 2 diabetes, osteoporosis and heart disease. Conclusion: Preventable causes of the increased morbidity and mortality, such as osteoporosis, chronic obstructive airway disease or type 2 diabetes, should be screened for. Despite the lack of randomized controlled studies, we recommend testosterone treatment in case of increased LH or low serum testosterone, and weight reduction programmes if overweight.