The new screenings will be conducted annually as part of service members’ required medical screenings for those 30 and older, he said. Troops under 30 can volunteer to be tested. In a video released on social media, Hegseth simply refers to troops, though it appears he is referring only to testing men in uniform for hormone irregularities.

The move comes as other Trump administration officials have begun to advocate for men to have easier access to testosterone replacement therapies, but the messaging from Hegseth and others blends known science on the hormone with broader, and less substantiated, claims.

When asked about what conditions Hegseth was looking to address with the new policy, the Pentagon referred to Hegseth’s remarks in the video that talked about keeping troops “strong, resilient and capable” and that the rigors of the modern battlefield demand “maximum psychological and mental readiness.”

The Pentagon would not offer specific conditions or diseases that were being targeted by the policy. In his video, Hegseth said receiving testosterone replacement therapy will be voluntary.

Over the past several years, special operations troops — and specifically Navy SEALs — have come under scrutiny for their use of testosterone and similar substances to enhance performance.

The death of a SEAL recruit during training in 2022 led to a discovery of substances in his possession, including testosterone, and revealed far more rampant drug use among the elite program than was previously acknowledged.

A year after the recruit’s death, the Navy said it would begin a drug-testing program to screen for “any hormonal substance, chemically or pharmacologically related to testosterone, that promotes muscle growth.”

Hegseth said his new initiative is “not about artificial enhancement.”

The Pentagon did not respond to questions about what research or academic studies underpinned the move. It also didn’t say if female troops would be able to be screened for lowering estrogen as they entered perimenopause.

Testosterone levels in men decline naturally with age and have long been linked to issues like erectile dysfunction, low libido, mood changes and weight gain. But experts have debated for years how to diagnose those problems and whether they should be treated by replacing the hormone.

Hegseth’s announcement comes as Health Secretary Robert F. Kennedy Jr. and other Trump administration officials are moving to make it easier for doctors to prescribe testosterone. Last month, the Food and Drug Administration proposed easing prescribing limits on testosterone gels, pills, patches and injections.

The current FDA label specifies that the medications are only for men with hypogonadism, a medical condition that causes drastically low testosterone.

But many influencers and proponents of Kennedy’s “Make America Healthy Again” movement tout testosterone as a way to look younger, build muscle and stay mentally sharp — although those uses aren’t accepted by most medical experts.

Still, recent studies have bolstered the case for testosterone’s benefits, for certain conditions, while allaying worries about its safety — particularly concerns about heart safety.

Last year, the FDA removed a boxed warning about possible risks of heart attack and stroke from the drugs.

Separately, a series of studies by the National Institutes of Health in older men found that taking testosterone improved erectile dysfunction, libido and other sexual measures and had a small effect on mood. But there was little or no improvement in other measures like fatigue, memory or overall well-being.

Other studies have shown potential improvements in muscle-building, strength and bone density.

However, current medical guidelines generally recommend against blanket testing of testosterone levels. Typically, doctors are advised to discuss testosterone therapy with men who have troubling symptoms and documented low levels of the hormone on two separate blood tests.

Testing for testosterone is challenging because levels of the hormone fluctuate throughout the day. Accurate testosterone readings are typically measured in the morning after fasting.