US Defense Secretary Pete Hegseth has ordered annual testosterone-deficiency screening for all active-duty and reserve service members aged 30 and older, claiming it will maintain military readiness. But five out of six men's health experts contacted by Reuters say they're puzzled by the move and worry it may lead to unnecessary - or even harmful - treatment.

Hegseth's mandate is one of several recent healthcare policy changes from Trump administration officials that have sparked debate over their scientific basis. He also reversed the military's flu vaccine mandate (later walked back after an outbreak) and the Department of Health and Human Services removed 17 members from its vaccine advisory panel.

Doctors note that testosterone levels naturally decline about 1% per year after age 30-40, but that doesn't mean everyone needs a prescription. The American Urological Association and the Endocrine Society recommend supplementation only for patients with confirmed deficiency and symptoms like reduced libido, fatigue, or decreased muscle mass. Giving testosterone without symptoms can cause overtreatment, leading to infertility, blood thickening, prostate issues, acne, hair loss, and mood volatility.

"If you just dole out the testosterone, the testes will shrink," warned Dr. Kevin McVary, a urologist. "And you can't reliably count on them coming back." Hegseth cited addressing "operator syndrome" in special forces as a goal, but Dr. B Christopher Frueh of the University of Hawaii, who first described the syndrome in 2020, noted that these operators are at an extreme end of the spectrum, with higher blast exposures - not representative of all troops.

Some experts see potential benefits. Dr. Haleem Mohammed of Gameday Health said broader screening could identify men with reversible causes of low testosterone, like being overweight. The Pentagon has not provided detailed guidance on how abnormal results will be evaluated or whether screenings will apply equally to females. Dr. Steven Nissen's study of over 5,200 men aged 45-80 found higher rates of atrial arrhythmia and bone fractures with testosterone therapy - findings with possible implications for the military.

In short, the new mandate may be putting the carriage before the horse, as one endocrinologist put it. But hey, at least we'll get some data on younger men.