The Trump administration is targeting testosterone deficiency as a potential threat to military readiness, rolling out new screening guidelines for male service members amid growing concerns about the health of American men and the shrinking pool of young people qualified to serve.

"There is absolutely a national defense readiness ramifications for [low testosterone]," Adm. Brian Christine, a senior Department of Health and Human Services official, told Fox News Digital in an interview.

Christine also pointed to broader health challenges facing the military's recruiting pool, warning that 77% of Americans ages 17 to 24 do not qualify for service without a waiver, with obesity, chronic disease and other barriers contributing to the problem. Among young men, he said, more than 70% are ineligible, while only about 3% of young Americans express interest in serving.

The warning comes as the Trump administration places a renewed emphasis on military readiness, with Christine helping shape an initiative that led the Pentagon to issue testosterone deficiency screening guidelines for male service members ages 30 and older in September.

Trump entered his second term with an aggressive approach to rebuilding the American military, tightening fitness requirements, axing DEI policies, overhauling weapons acquisition, building up recruitment and refocusing the force on combat readiness and lethality.

Christine, a urologist who spent more than 35 years specializing in men's health, said testosterone levels have been declining for decades, raising concerns about the long-term health of American men and the physical demands placed on those serving in uniform.

"I think it's incredibly important, incredibly timely," Christine said of the screening guidance.

Under the Pentagon's guidelines, male service members ages 30 and older undergo mandatory screening for testosterone deficiency, beginning with an assessment of symptoms and risk factors, with further testing and potential treatment available when medically appropriate.

"We're not forcing testosterone on anybody," Christine said. "But what we are doing is screening, taking those men who are symptomatic and have low numbers and offering them a pathway forward." The HHS official pointed to obesity and chronic disease as established factors associated with low testosterone, while raising concerns that environmental exposures, including microplastics and other toxins, could also be contributing to the decline — a possibility researchers are still investigating.

"In the mid-1970s, the average testosterone level for men in this country... was well over 650. Now it's approaching 350," Christine said.

National Institutes of Health Director Dr. Jay Bhattacharya echoed those concerns in a separate interview with Fox News Digital, warning that some testosterone deficiency may be going undiagnosed even as medical guidelines stress that a diagnosis requires both symptoms and consistently low hormone levels.

"It's interesting because if you look at the epidemiological trends, testosterone levels in the American male population have been declining over the last decades. And again, we don't know why. We don't have an answer," Bhattacharya said.

Bhattacharya said researchers must determine not only why testosterone levels are declining, but also what medical guidance should follow for men diagnosed with a deficiency. "There are under-diagnosed testosterone deficiencies." "The question of what to do about it, how to prevent it, that's at the top of my mind," he added.

The NIH director also pointed to declining sperm counts as another area requiring further scientific investigation, suggesting that environmental exposures could be contributing to broader reproductive health concerns.

"But even more importantly, what are the factors, probably environmental factors, that have led to the decline in sperm counts, for instance? We need an answer to those questions," Bhattacharya said.

Bhattacharya said the NIH is investing in research to better understand the potential causes of those trends and determine how doctors should advise American men.

Christine said that testosterone is about more than muscle growth or physical appearance, arguing that hormone levels play an important role in men's overall health.

"Testosterone levels in men are absolutely related to their overall well-being, to their lifespan, to their health span, and to their wellness," Christine said. He also noted that men with low testosterone tend to experience higher rates of anxiety and depression.

The administration is also developing separate hormonal health guidance for female service members, which the Defense Health Agency said would follow the September guidelines issued for male troops, with women's health specialists contributing to the recommendations, Christine said.

Christine said that the goal is ensuring that service members are equipped to perform their duties while addressing broader health challenges affecting American men.

"If we truly want our men who are in uniform to be at their best," Christine said, the focus must be on their ability to function and perform their jobs.