Male hypogonadism: pathogenesis, diagnosis, and management.

Organic male hypogonadism due to irreversible hypothalamic-pituitary-testicular (HPT) pathology is easily diagnosed and treated with testosterone-replacement therapy. However, controversy surrounds the global practice of prescribing testosterone to symptomatic men with low testosterone and non-gonadal factors reducing health status, such as obesity, type 2 diabetes, and ageing (ie, functional hypogonadism), but without identifiable HPT axis pathology. Health optimisation remains the gold-standard management strategy. Nevertheless, in the last decade large clinical trials and an individual patient data meta-analysis of smaller clinical trials confirmed that testosterone therapy induces modest, yet statistically significant, improvements in sexual function without increasing short-term to medium-term cardiovascular or prostate cancer risks in men with functional hypogonadism. Although testosterone improves bone mineral density and insulin sensitivity in these men, trials from the last decade suggest insufficient evidence to determine the safety and effectiveness of use of this hormone for the prevention of fractures or type 2 diabetes. This Review discusses the pathogenesis and diagnosis of male hypogonadism and appraises the evidence underpinning the management of this condition.