Testosterone deficiency in adult men remains one of the most underdiagnosed and simultaneously overtreated endocrine conditions in primary care — a paradox this comprehensive JAMA review addresses with updated clinical precision. For millions of men experiencing fatigue, reduced libido, cognitive fog, or declining muscle mass, understanding where the science actually stands on hypogonadism has direct, immediate implications.
The review synthesizes current understanding of both primary hypogonadism — originating from testicular failure — and secondary hypogonadism, which involves disruption along the hypothalamic-pituitary axis. Clinically meaningful testosterone deficiency is defined not by a single threshold but by the convergence of consistently low serum total testosterone (typically below 300 ng/dL on morning draws) with genuinely attributable symptoms. The narrative covers how conditions such as obesity, type 2 diabetes, and obstructive sleep apnea can suppress the hypothalamic-pituitary-gonadal axis, creating functional hypogonadism that may resolve with treatment of the underlying condition rather than testosterone replacement. Diagnosis requires at least two separate confirmatory measurements, with attention to sex hormone-binding globulin levels that affect free testosterone bioavailability.
What makes this review particularly valuable is what it implicitly pushes back against: the widespread clinical tendency to prescribe testosterone replacement therapy based on symptoms alone or on borderline lab values. The broader endocrine literature consistently shows that TRT prescriptions have surged far beyond confirmed hypogonadism prevalence. This review's emphasis on pathophysiological grounding before treatment initiation aligns with Endocrine Society guidelines but adds nuance around cardiovascular risk — an area recently complicated by the TRAVERSE trial, which found testosterone therapy did not increase major adverse cardiac events but did raise pulmonary embolism risk. For health-conscious adults and their clinicians, the practical takeaway is clear: rigorous diagnosis matters as much as treatment, and lifestyle-driven secondary hypogonadism deserves metabolic intervention first. An incremental but clinically important synthesis.