Testosterone, Free, Direct Unit Converter

Free testosterone is the small fraction of testosterone in your blood that circulates unbound to proteins. Only about 1–3% of total testosterone is free, but this is the portion that can readily enter cells and activate androgen receptors.

This test uses a direct analog immunoassay to measure free testosterone, as opposed to the more common calculated method that estimates free testosterone from total testosterone, SHBG, and albumin. The two methods use different reference ranges and results should not be compared directly.

Free testosterone may provide a more accurate picture of androgen status than total testosterone, especially when SHBG levels are abnormal due to obesity, liver disease, thyroid disorders, or certain medications.

Produced mainly in the testes (men), ovaries (women), and in smaller amounts by the adrenal glands.