Hypogonadism and metabolic syndrome: Implications for testosterone therapy

Purpose: Metabolic syndrome, characterized by central obesity, insulin resistance, dyslipidemia and hypertension, is highly prevalent in the United States. When left untreated, it significantly increases the risk of diabetes mellitus and cardiovascular disease. It has been suggested that hypogonadism may be an additional component of metabolic syndrome. This has potential implications for the treatment of metabolic syndrome with testosterone. We reviewed the available literature on metabolic syndrome and hypogonadism with a particular focus on testosterone therapy. Materials and Methods: A comprehensive MEDLINE review of the world literature from 1988 to 2004 on hypogonadism, testosterone and metabolic syndrome was performed. Results: Observational data suggest that metabolic syndrome is strongly associated with hypogonadism in men. Multiple interventional studies have shown that exogenous testosterone has a favorable impact on body mass, insulin secretion and sensitivity, lipid profile and blood pressure, which are the parameters most often disturbed in metabolic syndrome. Conclusions: Hypogonadism is likely a fundamental component of metabolic syndrome. Testosterone therapy may not only treat hypogonadism, but may also have tremendous potential to slow or halt the progression from metabolic syndrome to overt diabetes or cardiovascular disease via beneficial effects on insulin regulation, lipid profile and blood pressure. Furthermore, the use of testosterone to treat metabolic syndrome may also lead to the prevention of urological complications commonly associated with these chronic disease states, such as neurogenic bladder and erectile dysfunction. Physicians must be mindful to evaluate hypogonadism in all men diagnosed with metabolic syndrome as well as metabolic syndrome in all men diagnosed with hypogonadism. Future research in the form of randomized clinical trials should focus on further defining the role of testosterone for metabolic syndrome.