Study: about a quarter of male US Army soldiers could screen as low in testosterone

Mixed · 2A study published in JAMA on 15 October 2026 estimates that about 26 per cent of male active-duty US Army soldiers would get a low testosterone result, equal to roughly 100,691 men. 1 2 Mixed · 2The researchers, from the Pennington Biomedical Research Center in Louisiana and the US Army Research Institute of Environmental Medicine, used data from a military health survey at five installations. Morning fasting blood samples were collected between August 2024 and January 2026. 2 1 Mixed · 2Total testosterone was measured in 479 men, after excluding three who were receiving testosterone treatment. The weighted mean was 405 ng/dL, and the weighted mean age was about 30. Female personnel were not analysed because their levels were often below the limits of detection. 2 1

Mixed · 2The 26 per cent figure uses a cutoff of below 300 ng/dL, which the American Urological Association classes as low and which the Pentagon guidance also uses. With the lower Centers for Disease Control and Prevention reference cutoff of 264 ng/dL, the estimate falls to about 15 per cent. 2 1 Mixed · 2Low readings were more common with age: 33 per cent of men aged 30 and older were low, against 19.5 per cent of those under 30. Ars Technica adds that the odds also rose with body mass index. 2 1 Mixed · 2Defense Secretary Pete Hegseth announced the programme in July. All service members aged 30 and older must have annual screening and be offered voluntary testosterone replacement therapy if low. Younger personnel can opt in. Hegseth described the aim as "restoring and optimising your natural capabilities" and said there are no ramifications for declining therapy. The Pentagon issued clinical guidance in September. 1 2

Centre · 1Outside experts question the approach. Darren Katz of the University of Melbourne, who was not involved, says a single test is unreliable because levels vary with time of day, food, sleep, obesity, illness and stress. The American Urological Association advises diagnosis only when symptoms are also present. Katz says there is insufficient evidence that treatment improves military readiness, and he favours targeted, symptom-based testing. 1 Left · 1Ars Technica reports that the Endocrine Society and the American Urological Association have recommended against blanket screening. It says clinically significant male hypogonadism affects at most 1 per cent of men, and warns of cascades of follow-up testing, overtreatment and harms including infertility. The study authors note that published estimates of clinical hypogonadism are far lower than the share with a low reading. 2 Left · 1Actual testing numbers may be lower than the study implies, because the screening starts with questions about symptoms and risk factors. Ars Technica says those symptoms, such as "low motivation" and "disturbed sleep", are vague, and risk factors such as obesity and type 2 diabetes are common. Men with risk factors can be tested without symptoms, so many more soldiers will likely be tested than before. It is unclear how many under-30s will opt in. 2

Centre · 1Side effects of testosterone therapy named by New Scientist include acne, testicle shrinkage, reduced sperm production and fertility, and in older men a higher risk of fractures and pulmonary embolism. Timothy Piatkowski of the University of Queensland warns that testosterone is increasingly used as a proxy for masculinity, so high levels could be conflated with being a good soldier. 1