What a Testosterone Test Cannot Tell You About a Soldier

If you enjoyed this article, please share it with a friend or consider becoming a paid subscriber and supporting science literacy and sex education.

Share

Pete Hegseth has decided that the United States military has a testosterone problem.

Not a combat problem. Not a recruitment problem. And not the sort of problem created when soldiers are underfed, underslept, overtrained, sent through blast zones, and then expected to repair themselves with twelve minutes of telehealth and a pamphlet about resilience.

A hormone problem.

Under Hegseth’s new plan, service members over thirty will have their testosterone screened during their annual health assessments. For military personnel under 30, the test is voluntary. For military personnel over 30, it is mandatory. Anyone deemed deficient may be offered replacement therapy. Treatment is optional. The number is not.

Hegseth says this will keep troops on the “leading edge of lethality,” which is a phrase no doctor has ever used to describe the endocrine system.

Hegseth also calls this the “High-T Department of War.” I will continue calling it the Department of Defense because “Department of War” is merely a made-up, bogus title until Congress changes the law. You cannot permanently rename a federal department by shouting at the stationery.

But put the branding aside. What is the Department of Defense trying to accomplish with testosterone testing?

Does Hegseth believe a testosterone test will reveal which mechanic can repair a helicopter under fire? Which intelligence officer can spot a pattern before anyone else? Which infantryman will carry a wounded friend? Which commander will remain calm when a bad decision begins killing people?

The military already tests strength, endurance, judgment, discipline, technical competence, and a person’s ability to perform the job. Those are frustratingly direct measures of military readiness. Hegseth has chosen a blood test instead because a blood test appears to measure something he values more than performance — the “warrior ethos.” Which definitely is the title of a cheesy bodice ripper starring him.

Unfortunately, the endocrine system has not agreed to participate in his metaphor. And judging by the number of MAGA men applauding this test, it’s time for some T myth-busting.

Doctors do not diagnose low testosterone by drawing blood once and holding the vial up to the light like a gender-reveal candle. The Endocrine Society recommends diagnosing hypogonadism only when a man has symptoms consistent with testosterone deficiency paired with consistently low testosterone levels.

This may shock the podcast bros, but many healthy men have low testosterone. Very few of them are sick. Doctors sorted that out twenty years ago, which is why they don’t test men who feel fine.

The numbers might also surprise some. Nearly a quarter of men over 40 walk around with a testosterone number a screening program would flag, and most of them are perfectly healthy. Only about 1 in 20 have the symptoms that turn a low number into an actual diagnosis. Those are the men doctors can identify by how they feel, which is why they start there.

Hegseth’s scheme encourages people to view testosterone vertically — low is failure, high is victory — when endocrinology views it diagnostically: Is this level appropriate for this person, at this time, under these conditions?

Bottom line: Hormones have working ranges, not leaderboards in the endocrine Olympics.

Testing for low T is not like testing blood sugar levels. First, testosterone must be tested in the morning. Then the result is normally confirmed with a second morning fasting test. Further testing may then be needed to determine whether the problem begins in the testes, the pituitary gland, or the hypothalamus.

It’s a tricky test because testosterone is not a stable quantity of manhood stored in the bloodstream. There is total testosterone, free testosterone, and bioavailable testosterone. Most testosterone in the blood is bound to proteins, particularly sex-hormone-binding globulin and albumin. How much is bound changes how much is available to tissues. Levels also move over the course of a day, which is why the blood is usually drawn in the morning.

One laboratory result may be perfectly accurate and still tell an incomplete story about the person attached to it.

The next problem is that testosterone is a fickle little wench. Sleep loss can lower it. Severe energy deficits can lower it. Strenuous military training can lower it.

Studies of service members have documented testosterone declines during periods involving sleep deprivation, heavy exertion, and inadequate energy intake. Ranger School research is unambiguous. One 8-week study documented testosterone dropping to near-castrate levels under semi-starvation and ~3.6 hrs sleep/day; a JCEM field study found total testosterone fell ~70%.

Great. Hegseth has selected a lethality marker that may fall when soldiers do the things soldiers are ordered to do.

Testosterone also changes with social conditions. Partnered men average lower levels than single men. So I guess Pete’s warriors should find their local incel group.

Then there is fatherhood. Hegseth and the other MAGAmuffins are very worried about declining birth rates. Unfortunately, men who become fathers often experience substantial declines in testosterone. Caregiving lowers testosterone even more. Nature, in its usual refusal to consult political consultants, appears to have designed male physiology for more than one assignment.

A major meta-analysis found no relationship between naturally occurring testosterone and human aggression. When researchers experimentally administered testosterone, they found no overall causal increase in aggressive behavior. The simple equation — more testosterone, more violence — does not survive contact with the evidence.

The more interesting research suggests that testosterone is connected to status-seeking.

That is not the same thing as aggression. It means behavior changes according to what helps a person gain or protect status in a particular environment.

In one experiment, testosterone made men punish unfair offers more severely. It also made them reward generous offers more generously. Testosterone did not issue one moral command. It sharpened the response to behavior that affected status. Other studies have found that testosterone can encourage prosocial behavior when cooperation serves status, while reducing strategic niceness when submission to an audience does not.

Testosterone is not the hormone that whispers, Punch him. It is closer to the hormone that whispers, Do what puts you on top here. In a prison yard, that may mean violence. At a bargaining table, it may mean fairness. With Hegseth, that may mean screaming into a microphone while performing pull-ups with horrible form. Inside a stable hierarchy, it may mean recognizing rank and behaving accordingly.

The result depends on the person, the stakes, the audience, and the rules of the room.

Risk-taking is no cleaner. Author and researcher Cordelia Fine has spent years dismantling the idea that testosterone makes men crave danger. Risk changes by domain. A man may bungee-jump from a bridge and refuse to ask his boss for a raise. A woman may avoid the bridge and walk into a boardroom prepared to risk her income, reputation, and career.

Both are taking risks. Only one receives a commemorative video and a liability waiver.

A 2026 meta-analysis examined 52 studies involving more than 17,000 people and found no overall association between testosterone and risk-taking. Some narrow economic lottery tasks produced small effects. The larger claim — that testosterone reliably predicts a person’s willingness to take risks — did not hold.

Even testosterone therapy refuses to behave like a masculinity upgrade. The treatment sold as proof of male vitality can also make a man infertile by persuading his own testicles to clock out. The brain detects that plenty of hormone is circulating and reduces the signals — luteinizing hormone and follicle-stimulating hormone. The result? Reduced or stopped sperm production, infertility, and testicular shrinkage. Recovery after stopping treatment may take months.

Testosterone therapy can also raise hematocrit by increasing red blood cell production. Erythrocytosis — a higher-than-normal concentration of red blood cells in the body — is the most common dose-limiting side effect. Which is why patients require blood monitoring and are advised not to start treatment if their hematocrit is elevated.

Every testosterone formulation studied by the FDA also raised blood pressure.

And then there are products sold as “testosterone boosters,” a market where the word natural performs most of the medical supervision. Some contain ingredients with little evidence they raise testosterone. Others have been found with undisclosed drugs. The FDA found one male-enhancement product containing undeclared sildenafil, tadalafil, and testosterone propionate.

The endocrine system is a feedback loop, not a gas tank. Pouring in more does not necessarily make the engine roar.

None of this makes testosterone unimportant. It helps regulate muscle mass, bone health, red blood cell production, sexual function, and fertility. Men with genuine hypogonadism can suffer real symptoms and may benefit from treatment.

Here’s the difference between science and Hegseth’s warrior ethos. Medicine begins with the patient and asks what is wrong. Ideology begins with the desired man and asks which patients fail to resemble him. The former is used as a diagnostic tool. The latter is used as a eugenics-adjacent sorting tool.

The sales pitch requires a second belief: that higher testosterone levels produce the qualities needed for war. Aggression. Courage. Risk. Dominance. The full gas-station supplement display. But testosterone is not bottled manliness.

It’s not hard to imagine where testosterone tests are headed. Men will compare numbers in locker rooms. Someone will claim his result was low because he slept badly. Someone else will display his like a batting average. A market will appear to sell every powder, pellet, injection, and gummy capable of raising it. Commanders will say the results are private until the results become relevant.

That is how a medical measurement becomes a social rank. Not through one dramatic order. Through repetition, files, and pressuring glances.

Treatment may remain voluntary, but the number will still exist. It will exist beside a name, a rank, an age, a unit, and a career. It will be available whenever an institution needs a reason to explain why one man advanced and another did not.

That should concern anyone building a military around the fantasy of maximum dominance. Armies are hierarchies. They require people to obey orders, share danger, protect weaker members of a unit, and trust that the person beside them will not decide halfway through a firefight that cooperation is for men with inferior biomarkers.

If Hegseth is picturing Spartacus, he should bring back the people who understand the hypothalamus.

Carlyn Beccia is an award-winning author and illustrator of 13 books. Subscribe to Conversations with Carlyn for free content every Wednesday, or become a paid subscriber to get the juicy stuff on Sundays.