Testosterone Test: What Your Levels Mean

Testosterone is the primary androgen, or male sex hormone, but it is also important in women. Total testosterone measures all testosterone in the blood, including the portion bound to proteins. Free testosterone measures the small fraction that is biologically active.

Most testosterone is bound to sex hormone binding globulin (SHBG) and albumin. SHBG levels can change with age, liver health, thyroid status, and certain medications, which is why free testosterone sometimes gives a clearer picture than total testosterone.

In men, low testosterone can cause low energy, reduced libido, mood changes, loss of muscle mass, and decreased bone density. In women, low levels can also affect libido, mood, and bone health, while high levels can be associated with conditions such as PCOS.

Testosterone naturally declines with age in men. Interpretation should always consider symptoms, timing of the test, and other hormones.

The body makes testosterone from cholesterol. In men, the testes produce most testosterone. In women, the ovaries and adrenal glands contribute. There is no meaningful dietary source of testosterone, but adequate zinc, vitamin D, healthy fats, sleep, and resistance exercise support natural production.

Age, sex, time of day, sleep quality, body weight, stress, alcohol, medications such as opioids or steroids, thyroid and liver health, and SHBG levels can all affect testosterone results. Men have roughly 10–20 times higher testosterone than women.