Suspected Hegseth low T screening may reveal up to 25% of the military

Medical experts strongly advise against blanket screenings.

According to a study published Thursday in JAMA, up to a quarter of active-duty members of the military can get a low testosterone result from mandatory military screening, although the true prevalence of the condition is likely a small fraction of that figure.

The finding adds to concerns that mandatory screening announced by Defense Secretary Pete Hegsett in July will lead to a series of unnecessary medical assessments for members of the military. These assessments can lead to inappropriate tests, incorrect results and diagnoses, and overtreatment, which can cause harm, including infertility. Medical professionals, including the Endocrine Society and the American Urological Association (AUA), have recommended against blanket screenings for these reasons. However, the Pentagon has moved forward with plans to release clinical guidelines in September.

The JAMA study sheds light on the reasons why testosterone levels aren't being measured in asymptomatic men — and also shows how many members of the military may be caught in clinically questionable screenings.

Researchers from the Pennington Biomedical Research Center in Louisiana and the US Army Research Institute of Environmental Medicine in Massachusetts conducted the study. The researchers obtained data from a large military health survey that included members of the five US militaries. The survey data set included morning blood draws from fasting military members. The samples were collected between August 2024 and January 2026.

From these samples, total testosterone levels were measured from 479 active military men. (Those treated with testosterone were excluded from the study—three men were excluded for this reason.) With some statistical weighting, the 479 members were representative of active-duty US military personnel. The weighted average age was about 30 years and the weighted average body mass index (BMI) was 28.4, which is in the "overweight" category.

In general, experts caution against universal screening of men for low testosterone because testosterone measurements can be highly variable and unhelpful. Levels can drop for a variety of reasons, including age, time of day, obesity, illness, physical stress, poor sleep, trauma, and various medications. Additionally, a condition that can cause a clinically significant decrease in testosterone—a condition called male hypogonadism—is rare, affecting up to 1 percent of men. They include genetic conditions and problems with the pituitary gland.

Due to the complexity, experts recommend that evaluations be done by patients who report their symptoms. In these cases, doctors use repeated tests and comprehensive evaluations to arrive at a definitive diagnosis of male hypogonadism. Given the current norm, researchers are not sure exactly what the new military will display on the global web.

According to new data, a large part of the military may face alarming results. Among the military members surveyed, the weighted mean total morning testosterone was 405 ng/dL. The Pentagon clinical guideline uses a threshold of less than 300 ng/dL for low testosterone, consistent with AUA recommendations. Using this cutoff and extrapolating the data to the entire military population, researchers estimate that about 26 percent of active-duty military personnel receive a test result indicating low testosterone.

The Centers for Disease Control and Prevention has a harmonized reference cutoff that is slightly lower, 264 ng/dL. At this threshold, about 15 percent of military personnel are estimated to have low testosterone.

As expected, the likelihood of low outcomes scaled with weight and age. The older the age and/or the higher the BMI, the greater the chance of having testosterone below either of these thresholds. Of men under 30, 19.5 percent had low measurements, while 33 percent of men 30 and older had low levels.

"Published estimates of clinical hypogonadism are significantly lower than the prevalence of low testosterone observed here, suggesting that many men with a low screening measure do not have clinical hypogonadism," the researchers write. But any positive screening result requires thorough follow-up, including repeat testing, further evaluation, counseling about modifiable factors (such as weight loss or improved sleep), and treatment considerations, the researchers noted.

"Because testosterone replacement therapy is long-term and has potential side effects, it is important to recognize a low screening value apart from clinically significant hypogonadism," they write.

While the study looked at the results of all men — without first assessing men for possible symptoms of hypogonadism — the military's screening is likely to be more limited. Mandatory screening only applies to men aged 30 and over, while younger men are allowed to participate. It is unclear how many will do so. The first step in screening is to ask members about possible symptoms and risk factors. Because of that, some men may not get tested for testosterone.

However, symptoms and screening for risk factors will likely involve a large portion of the military, resulting in more military personnel being tested than ever before. Possible symptoms include vague problems not closely related to male hypogonadism, such as "reduced physical performance," "disturbed sleep," and "low motivation." Considered risk factors also include common conditions such as obesity, type 2 diabetes, and low-traumatic fractures. According to Pentagon guidelines, people with such risk factors can be tested even if they have no symptoms.

Beth is Ars Technica's senior health reporter. Beth holds a Ph.D. in microbiology from the University of North Carolina at Chapel Hilo and attended the Science Communication Program at the University of California, Santa Cruz. He specializes in coverage of infectious diseases, public health and microbes.