Do I Need A Testosterone Test? A Doctor Explains—And What The Results Mean

A new JAMA study found that about 1 in 4 U.S. Army service members have a testosterone level below 300 ng/dL. This includes nearly 1 in 5 men under 30. On the face of it, it appears young, fit men have “low T.”

But here’s the issue: every participant in the study had just one morning blood draw. And a single low reading isn’t a formal diagnosis of hypogonadism, the technical term for low testosterone level.

Testosterone testing in men is an area with many misunderstandings. Symptoms of testosterone deficiency overlap with other more common issues: poor sleep, stress, depression, thyroid disease as well as normal aging.

Therefore, it’s possible to have symptoms of testosterone deficiency and a single abnormal test, but to have another issue causing the symptoms that’s unrelated to your testosterone level.

Here is my thinking on should be tested, how to get an accurate result and what the numbers actually mean.

Symptoms That Should Prompt A Testosterone Test

Low testosterone levels show up as a cluster of symptoms. For example, in sexual function, there can be a low desire, erectile change, or a fall in morning erections. It can be linked to persistent fatigue or low motivation. Men can lose mass or strength or gain weight. Sometimes there can even be hot flashes.

Some symptoms like sexual dysfunction are specific to testosterone deficiency, while others like fatigue have more causes.

Regardless, the presence of these symptoms without another cause may prompt a physician to order a testosterone test.

Here’s How Doctors Make The Diagnosis Of “Low T”

The two medical groups that write guidelines on testosterone testing, the Endocrine Society and American Urological Association recommend that hypogonadism should only be diagnosed in men who have both symptoms and signs of deficiency plus testosterone levels that are clearly and consistently low.

So, a low lab value without symptoms isn’t enough. Neither are symptoms without a low lab value.

That’s also why routine testing of men without symptoms isn’t recommended. I made this point when the Pentagon launched a mandatory testosterone screening program for service members this past summer. Thankfully, the mandatory nature of screening service members has since been rescinded.

The reason is that true deficiency is, in fact, uncommon in young, healthy men. Mass testing like this mostly turns up borderline numbers that can sometimes invite unnecessary treatment.

Testing makes the most sense for men with consistent symptoms, particularly those with risk factors. That can include obesity, type 2 diabetes or long-term opioid or steroid use. Prior chemotherapy or testicular injury, pituitary disease, or unexplained infertility or bone loss are also risk factors to consider.

How To Get An Accurate Testosterone Test

An important point is that time of day matters. Testosterone peaks in the morning and falls through the day. In a Boston study, men aged 30 to 40 had levels 20% to 25% lower at 4 p.m. than at 8 a.m. Some men who tested low in the afternoon were normal at when they tested in the morning.

To get a result you can trust:

• Test in the morning, fasting. Early-morning blood draws capture peak levels.

• Repeat it. Guidelines call for confirming a low result with a second morning test on a different day.

• Start with total testosterone. Free testosterone and sex hormone-binding globulin (SHBG) help when total testosterone is borderline or when obesity, aging, thyroid disease or liver disease may be shifting SHBG.

• Avoid testing when you’re sick or after a stretch of short nights.

Poor sleep is an important contributor. In a University of Chicago experiment, healthy young men limited to five hours of sleep a night for one week saw their daytime testosterone fall 10% to 15%.

Having worked many overnight ER shifts in my years, I tell patients not to schedule this test after a week of bad sleep.

What Your Testosterone Numbers Mean

Most labs report total testosterone in nanograms per deciliter (ng/dL). Reference ranges vary by lab and assay. Therefore, it’s important to compare your result with the range printed on your own report.

Many research studies use about 300 ng/dL as a cutoff. The TRAVERSE trial, the large-scale clinical study that evaluated the long-term cardiovascular safety of testosterone replacement therapy in middle-aged and older men with low testosterone, enrolled men with two fasting levels below 300.

Here are the lab results on your report and how you should think about them:

• Total testosterone is all the testosterone in your blood, bound and unbound.

• SHBG is the protein that carries testosterone. High SHBG can make total testosterone look normal while the usable fraction is low, and low SHBG can do the reverse.

• Free testosterone is the small, unbound fraction your tissues can use. It’s most reliable when calculated from total testosterone and SHBG or measured by a specialized lab method.

• Luteinizing hormone (LH) is the pituitary signal that tells the testes to make testosterone. It can helps pinpoint where the problem is.

A confirmed low level at repeated time points, drawn in the morning are the first step toward a diagnosis. The next step is finding the cause.

Primary hypogonadism means the testes aren’t producing enough testosterone. In those cases, LH is usually high. Secondary hypogonadism means the pituitary or hypothalamus isn’t sending a strong enough signal, and LH is low or normal.

Secondary causes are common. They are also sometimes reversible. That includes obesity, poorly controlled diabetes, opioid use and untreated sleep apnea, which can all suppress testosterone.

Your clinician may also check prolactin, iron levels or pituitary imaging when the picture warrants it.

This is why the urology guideline recommends counseling every man with low testosterone on lifestyle changes. Weight loss, regular exercise and better sleep can raise levels meaningfully in some men.

What To Know Before Starting Testosterone

Testosterone treatment can help the right patient. Yet the benefits are sometimes more modest than marketing suggests. In the Testosterone Trials, 790 men aged 65 and older with low levels who received testosterone gel for a year saw moderate improvements in sexual function and some improvement in mood, but no gain in energy or walking distance.

It’s also important to know that if you are recommended to take testosterone that it is safe from a cardiovascular perspective.

TRAVERSE followed 5,246 men aged 45 to 80 with heart disease or high cardiovascular risk. Major cardiac events occurred in 7.0% of men on testosterone and 7.3% on placebo. Importantly, those results apply to men with confirmed deficiency treated for about two years, not to men using testosterone to push normal levels higher.

There are also several other issues to discuss with your doctor. Fertility, for example, is often an important reason not to take it. Testosterone therapy suppresses sperm production. Men hoping to conceive soon should generally avoid testosterone therapy.

Guidelines also call for checking testosterone levels, red blood cell counts (hematocrit) and prostate cancer risk, especially in the first year.

Stopping testosterone treatment can be tricky. It can bring symptoms back and even worsen them. So being on testosterone is often a long-term decision. For men on it for a long period of time, it can be difficult to wean off, and it can sometimes take a long time for the body’s testosterone production to kick back in.

Ultimately, here’s how to think about it. A testosterone test is worth getting if you have consistent symptoms, especially sexual ones, or risk factors for deficiency. Get it in the morning and repeat it if it’s low. And make sure someone looks for the cause before prescribing a fix.

This article was originally published on Forbes.com