Testing Your Testosterone Levels? Know the Difference Between Free T and Total T

Testosterone deficiency (or hypogonadism) often entails an unsettling list of possible symptoms: you might gain weight more easily, for example – and in the form of fat, not muscle. Or you could find yourself with a lower sex drive than usual. Or, perhaps, you’ll feel as if a constant lethargy is smothering your mind’s ability to focus, make quick-and-accurate decisions, and feel good.

If you are experiencing these or other warning signs that you might have a testosterone imbalance, then consider checking your testosterone levels with EverlyWell’s at home Testosterone Test. It’s important to have normal testosterone levels, regardless of your gender, because testosterone is a hormone that’s absolutely essential for healthy metabolism. (For instance, optimal levels of testosterone help your body burn fat and gain more muscle.)

To determine your testosterone level, testosterone tests measure specific markers in your body – such as total testosterone or free testosterone. EverlyWell’s Testosterone Test measures your level of free testosterone because this marker can give you a better understanding of why you might be experiencing symptoms of testosterone deficiency.

Why is this the case, though – and what’s the difference between total testosterone and free testosterone, anyway?

Testosterone in the body: free T vs. total T

In men, most testosterone is made by the testes through a complex series of biochemical reactions – which convert cholesterol into testosterone (the adrenal glands also produce some testosterone).

Testosterone molecules are then secreted directly into the bloodstream – where many of them soon bind to other molecules known as sex hormone binding globulin, or SHBG (testosterone, as you may know, is a sex hormone). Other testosterone molecules bind to albumin – an important type of blood protein.

And the rest of your testosterone – the unbound testosterone? This testosterone is – quite appropriately – termed “free testosterone,” or free T, because it isn’t attached to other molecules. Your body actively uses free T molecules since they are at liberty to enter the body’s cells – unimpeded by SHBG or albumin – to carry out their function as signaling molecules that regulate metabolism and other cellular functions. (Testosterone molecules that are bound to other proteins cannot enter most of your cells.)

If that’s free testosterone, then what is total testosterone?

Total testosterone is a measure of how much testosterone you have in your blood in total – both free and bound. (So you’ll always have a higher level of total T than free T.)

Generally speaking, you’ll have lower levels of free T if you have more SHBG – with more SHBG molecules in your blood, a greater amount of your testosterone will be bound and not at all free.

Measuring testosterone: free T vs. total T

Suppose a man was experiencing some of the symptoms of hypogonadism (testosterone deficiency), like low libido, difficulty concentrating, brain fog, and constant low energy. So he decides to measure his total testosterone – but discovers that his total T level is perfectly normal. Nevertheless, he’s going through very real, very debilitating symptoms of hypogonadism – so what could be the issue?

It turns out that symptoms of testosterone deficiency aren’t only caused by the total amount of testosterone in your blood. When it comes to hypogonadism, the level of free T matters, too – because free T is what your body has readily available in the bloodstream. So you could have normal total T levels, but still suffer from the grueling consequences of testosterone deficiency because your free T levels are too low (which can be due to a high amount of SHBG in your blood).

Thus, your free T levels can shed light on why you may be experiencing signs of testosterone deficiency – even if your total T levels are normal. In fact, research suggests that free T levels are a better predictor of testosterone deficiency symptoms than levels of total T are. What’s more, low levels of total T don’t necessarily point to a testosterone-related health issue, since this might be simply a “side effect” of something else going on in your body.

For example, obesity can lead to a decrease in total T levels, since insulin resistance – a common consequence of obesity – lowers SHBG levels, causing total T levels to drop, as well. However, in a scenario like this, free T is often not affected and remains at a normal level.

So while low total T levels tell you that something might not be quite right with your health, low levels of free T can help you pinpoint a possible cause of testosterone deficiency symptoms.

(If you are experiencing such symptoms, EverlyWell’s at home Testosterone Test is a quick and easy way to check your free testosterone levels.)

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