Not all testosterone is created equal.
Testosterone matters. This vital male sex hormone plays a key role in regulating important bodily functions from how much weight you can lift to energy levels, sex drive, and more. But not all testosterone is equal. Testosterone is found throughout your bloodstream in two main forms: total testosterone (total T) and free testosterone (free T).
Differentiating between your total testosterone and free testosterone levels is a key part of understanding how testosterone works in your body as well as how to optimize your health.
Testosterone tests like the at-home analysis from Hone measure both total testosterone and free testosterone. Physicians analyze these biomarkers, along with others, to determine whether your hormones are balanced, but free testosterone (sometimes called bioavailable testosterone) is particularly helpful to measure, especially if you are experiencing symptoms associated with low T.
Total T is the total amount of testosterone, measured in nanograms per deciliter (ng/dL) of blood, in your body. On the other hand, free testosterone is the type of testosterone your body uses; it’s vital to your health. The more free testosterone you have, the better.
Most of the testosterone in your body is what’s called “bound,” explains family physician Nick Dahl, D.O., who treats men with low testosterone (hypogonadism).
Total testosterone is attached to proteins such as sex hormone binding globulin (SHBG) or albumin and is transported around your body from place to place.
It’s not usually, as Dahl says, “active.” In other words, it doesn’t have bodily effects in and of itself. Instead, total testosterone is metabolized into many other substances which are then used in other bodily processes, Dahl explains.
Free testosterone isn’t bound to anything, so it’s free to get into cells and get to work.
Free testosterone is responsible for the creation of secondary sexual characteristics in men, like facial hair and a deeper voice.
On a muscular level, free testosterone helps muscles contract. For an organ like the heart, free testosterone helps muscles pump more efficiently. Some research (1) suggests that men with congestive heart failure who also have low free testosterone have poorer health prognoses. If your free testosterone levels are below normal, you might have a lower risk of clogged arteries or a heart attack, he adds.
Because free testosterone helps you maintain muscle mass, when your numbers are higher you won’t gain as much fat, (2) he adds. Free testosterone also helps men with issues such as erectile dysfunction (ED).
Free testosterone levels should ideally make up between 1 to 2% of testosterone in your body. You can have normal levels of total testosterone, but low levels of free testosterone says Dahl.
Generally, though, “low” total testosterone is thought of as anything below 300 ng/dL. “Everybody will agree that below 300 is low,” says Dahl. “But a lot of people will say that men can get benefits if you treat them up to 450 (ng/dL).” That’s because low testosterone symptoms can be influenced by free testosterone—even if your total testosterone is “normal.”
Total Testosterone levels, and in turn, free testosterone levels (3), start to decrease around age 30 by about 1 percent every year. Genetics, your activity level, and your overall health also play a role in testosterone levels.
It’s hard to give an exact definition of “normal” testosterone levels without knowing someone’s lifestyle (if you’re inactive, you likely don’t need as much T as if you run marathons, for example). However, free testosterone levels typically lower with age.
Some companies only test for total testosterone levels, but excluding free testosterone levels is more likely to result in an inaccurate diagnosis.
It’s critical to test both free testosterone levels and total T, along with other biomarkers like SHBG and estrogen. It helps provide more context, says Dahl. For example, if your total T levels are normal, research finds that symptoms of low testosterone can still exist.
Having too little free testosterone can lead to symptoms of low T like fatigue, low sex drive, erectile dysfunction, and depression (3).
Testosterone testing (you can measure just total T or both total and free T) helps deliver results and sometimes is even used to diagnose health conditions such as erectile dysfunction or infertility.
Hone’s at-home hormone assessment paints a full picture of what’s going on with your free testosterone and total testosterone. The test also measures several biomarkers, including SHBG, estradiol, luteinizing hormone (LH), and prostate-specific antigen (PSA), and of course, both free and total T.
Testosterone is found throughout your bloodstream in two main forms: total testosterone (total T) and free testosterone (free T). Free T is the type of T your body uses but it’s important to know both numbers. If your T levels are low, testosterone replacement therapy (TRT) can help get them back within the normal range.
Hone’s at-home testosterone assessment is the simplest way to uncover whether your levels are low. If you qualify for treatment, TRT can be sent right to your door.
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