Male hypogonadism and testosterone therapy: current clinical evidence and controversies

Male hypogonadism, also referred to as testosterone deficiency (TD) in several clinical guidelines, is a common but frequently underdiagnosed condition that affects multiple domains of male health. This narrative review summarizes current evidence on the diagnosis and management of male hypogonadism, with emphasis on testosterone replacement therapy (TRT). Advances in the understanding of testosterone physiology, particularly the saturation model, have reshaped clinical perspectives. We review the effects of TRT on sexual function, metabolic health, bone density, mood, and physical function. Its relationship with cardiovascular risk, prostate safety, and lower urinary tract symptoms is also examined, highlighting the reassuring findings of the landmark TRAVERSE trial (Testosterone Replacement Therapy for Assessment of Long-term Vascular Events and Efficacy trial). Evidence also supports cautious use in men with comorbidities such as obstructive sleep apnea and previously treated prostate cancer. A guideline-based, individualized approach, prioritizing symptomatic men with confirmed biochemical deficiency, remains essential to optimize outcomes while minimizing risks.