Testosterone doesn’t mean what most people think it does

(CNN) — “Hey doc, can you order me labs? I want to get my T checked.”

As a urologist, I’ve gotten some version of that message more often in the past few months than in the rest of my career. Testosterone talk has moved from locker rooms to podcasts and now to headlines. US Defense Secretary Pete Hegseth announced on Wednesday the launch of screening for low testosterone among service members who are 30 or over.

Guys who never used to think about their health are suddenly asking real questions about their hormones — and guys who never knew the test existed could soon be getting it by default.

The interest is a good thing. What we do with a single number is the harder question.

If you’re curious about your testosterone, go ahead and have a urologist check it. And if there is a real pattern that suggests “low T” — months of low drive, fatigue, mood changes, muscle loss and weakness — then definitely make an appointment.

You and your doctor should consider two things before anyone talks replacement therapy. Rule out the bigger lifestyle factors first: sleep, alcohol, weight, stress, sleep apnea and the medications you’re already on. And if you might want kids someday, have that conversation before the first dose.

Because a number on a lab report is a starting line, not a finish line. The men who get real value out of knowing their T levels aren’t the ones chasing a higher number. The patients willing to ask what the number may tell them are on the right track.

What testosterone actually is

Triggered by signals from the brain, the testicles produce testosterone — the primary hormone driving male growth and development. These hormone levels fluctuate constantly, running highest in the morning and lower by the afternoon. Just how much testosterone the body releases changes based on sleep, weight, workouts and even stress. This key sex hormone also naturally drops about 1% a year once a man hits his 30s or 40s.

Most labs call normal somewhere between 300 and 1,000 nanograms per deciliter. That’s a wide range, and where “low” begins depends on which guideline your doctor follows and which lab ran the test.

And a diagnosis of low testosterone is never the result of one blood draw. Your doctor will check your T levels, alongside other labs (such as the hormone estradiol and the sex hormone-binding protein globulin), at least twice. This process helps rule out the other factors that can drive a number up or down.

The conversation almost nobody’s having

If a man truly is low, treatment usually means taking testosterone through a gel, a patch or an injection. Sometimes a doctor prescribes implanted pellets. If a patient is running too high, usually from supplements or too big a dose, the fix is to cut back and let the body recalibrate.

For a man who’s truly low and symptomatic, the upside is real: energy, drive, mood, muscle, bone. The goal is a normal level, not a high one.

Raising the number isn’t free. Testosterone therapy shuts down your body’s own production, and with it, sperm. Fertility can fall within weeks and doesn’t always come back. And most of the men I would treat are young enough to want kids. That conversation must happen before the first dose, not afterward.

Pushing levels too high carries its own risks: thicker blood and a higher clot risk, higher blood pressure, worse sleep apnea, and over time, shrinking testicles as the body stops making its own.

A low number usually has a story behind it

Firefighters are a good example. A study of 341 career firefighters in Florida showed about 11% had low testosterone and another 26% were borderline.

Those findings may sound like proof the job wrecks your hormones. But look more closely, and the men with low testosterone were older, heavier and in worse metabolic health, with higher blood pressure. The low number was traveling with those problems, not causing them.

I see the same thing in my office on a weekly basis. Men come in certain their hormones are off, and the blood work is fine. What’s actually broken is a patient getting five hours of sleep and having a drink every night to cope with a job they dislike. I wrote last year about what I called the testosterone trap — most men who think they’re low actually aren’t.

The military has studied testosterone

Even when you do raise your testosterone levels, you may not get what you came for. The US military has spent years putting that exact idea to the test. What researchers found was raising the number does not always equal improvement in performance.

In two US Army-funded trials called Optimizing Performance for Soldiers, researchers gave testosterone to young, healthy men during a long stretch of exercise and underfeeding. All these men had normal testosterone levels.

The men on testosterone held on to more muscle in a 2019 study. But their strength and endurance dropped just as much as the men who got nothing. A follow-up study in 2022 found the same: Testosterone prevented losses in lean mass but not physical performance.

That doesn’t mean testosterone never helps. In older men who have genuinely low levels, research has shown testosterone replacement therapy can improve strength and physical function, especially paired with training.

The same logic would apply to a service member who is truly hormone deficient — replacement therapy could help. But that wasn’t what the military trials tested. In their studies, soldiers weren’t deficient. They were young and fit, and pushing normal levels higher bought muscle without buying performance.

Testosterone helps the man who’s truly low. The hormone therapy doesn’t turn a normal number into a better one.

Your number says more about you than you’d think

There is a real reason to care about testosterone levels beyond libido and performance gains.

Dr. Mohit Khera, a professor and the F. Brantley Scott Chair in Urology at Baylor College of Medicine in Houston who coauthored the landmark TRAVERSE study on testosterone and heart safety, has said testosterone is one of the best markers of a man’s overall health — not just his sex life. Men with low T levels, he notes, carry higher rates of heart disease and bone fractures.

So if your testosterone is low, the most useful thing about that result is what the number is telling you about your heart, weight, sleep and metabolism. Sometimes the medically appropriate response is to raise testosterone levels. Just as often, the right response is to ask why your T has dropped.

But should every man over 30 be screened?

For a lot of men, a simple blood draw is the first time they’ve engaged with their own health. The curiosity over the test could be a way to get a lot of patients comfortable with the idea of screening for other problems. None of this testing is currently standard of care, but it’s worth a conversation.

American Urological Association guidelines recommend testing men who have symptoms rather than screening everyone. Personally, I hope the guidelines eventually give us more leeway to check — I think there’s value in catching testosterone deficiency earlier for more men. But updating the standard of care should only happen with evidence that it’s warranted, and we’re close but not there yet. Until the data moves, the guideline is the guideline, and I try to practice by it as best I can.

Either way, checking the number was never the hard part. Not every low number needs treatment, and not every man who raises his testosterone levels gets what he expects.

There is a growing interest in checking testosterone across the board once men reach a certain age. On the surface it sounds proactive. More screening, more early detection, more men engaged in their health.

But screening a whole population is not the same as testing a man who has symptoms. It’s a higher bar, and for good reason. When you check everyone, you catch a lot of borderline and low-normal numbers in men who feel completely fine, and every one of those results starts a conversation, and sometimes a prescription, that may not be needed.

But look at it from a different angle. Men are notoriously bad at showing up at the doctor’s office, and if a testosterone check is the thing that finally gets a 35-year-old in the door, I’m not going to pretend that has no value. The trick is making sure the number opens a real evaluation of health instead of becoming a shortcut to a prescription.

Why doctors screen for some things and not others

Doctors screen for plenty of things before symptoms show up, based on age and risk factors. Colonoscopies start in the mid-40s. Cholesterol and blood sugar get checked on a schedule as a patient gets older — or earlier if there is a family history. Testing for prostate cancer gets discussed around age 50.

What those screenings have in common is that they cleared a bar: The disease is common and serious, and catching it early changes what happens to you. The test reliably separates the people who have a problem from those who don’t.

Testosterone hasn’t cleared that bar yet. A low number in a man who feels completely fine hasn’t been shown to be a condition you’re better off catching early — and that, not whether men’s health matters, is the line between screening and testing.

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