Testosterone, Free (Serum/Plasma)

Why This Test Might Be Ordered

Your healthcare provider may order this test to evaluate hormone balance, diagnose conditions like low testosterone (hypogonadism), or assess symptoms such as low libido, fatigue, or irregular menstrual cycles. It can also help monitor conditions like polycystic ovary syndrome (PCOS) or evaluate treatment responses for hormone-related disorders.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a specific protocol. Avoid alcohol for 24 hours before testing. If you’re on hormonal medications, let your provider know—some may affect results.

What the Results Mean

Results are interpreted based on your age, sex, and overall health. Free testosterone levels can vary widely, so your provider will compare your results to your baseline or clinical context rather than a single reference range. Abnormal results may prompt further testing or follow-up.

Common Conditions Linked to Free Testosterone

Low free testosterone can cause symptoms like reduced sex drive, muscle weakness, or mood changes. High levels may indicate conditions like Cushing’s syndrome or tumors. Your provider will discuss these findings in relation to your symptoms and medical history.