Testosterone, Free (Serum/Plasma)

Why Is This Test Done?

Your healthcare provider may order this test to evaluate hormone-related conditions, such as infertility, low libido, menstrual irregularities, or symptoms of hormone imbalances. It can also help diagnose or monitor conditions like polycystic ovary syndrome (PCOS), androgen excess, or hypogonadism in both men and women.

What Does It Measure?

Free testosterone is the portion of testosterone that is not bound to proteins in your blood and is therefore biologically active. Unlike total testosterone, which includes both free and bound forms, free testosterone reflects the hormone’s true impact on your body.

Sample Collection and Preparation

This test requires a blood sample drawn from a vein in your arm. The sample is collected in a tube that separates serum or plasma from blood cells. The specimen is then sent to a lab for analysis using immunoassay methods, which detect the hormone’s presence with high sensitivity.

What to Expect Before the Test

No special preparation is needed, but you may be asked to avoid certain medications (like certain birth control pills or hormone therapies) that could affect results. If you have a history of bleeding disorders or take blood thinners, let your provider know before the test.