Testosterone Therapy in Older Men: Present and Future Considerations

Testosterone is the classical male anabolic hormone, involved in sexual development, virilisation and regulation of body composition in adult men. Organic disease involving the hypothalamus, pituitary or testes may interfere with endogenous testosterone production. In such men, testosterone treatment effectively ameliorates symptoms and signs of androgen deficiency. However, non-gonadal factors including age, body mass index and medical comorbidities influence circulating testosterone, and older men have on average lower testosterone concentrations compared with younger men. In these men, testosterone treatment would be a pharmacological intervention requiring stringent justification via high-quality evidence from randomised controlled trials (RCTs). Recent RCTs show benefits of testosterone treatment to improve sexual function, anaemia and bone mineral density in older men, and to prevent or revert type 2 diabetes mellitus in men at high risk. Results from a large cardiovascular safety trial in men with or at risk of cardiovascular disease provide important reassurance as to cardiovascular and prostate safety of testosterone treatment. Key questions remain as to whether testosterone's anabolic and other effects can be used safely to counter reductions in lean mass associated with incretin-based weight loss medications in men with obesity, and whether it might prevent disabilities including frailty, osteoporotic fractures and dementia in older men generally. This last question could be answered by a new testosterone RCT, targeting men in the 65-80 years age bracket, which would necessarily be large and of extended duration. A composite endpoint could be used which integrates potential benefits and risks, such as disability-free survival.