Free testosterone (serum/plasma mass concentration)

Why This Test Is Done

Your healthcare provider may order this test to evaluate hormone levels, diagnose conditions like low testosterone (hypogonadism) or high testosterone (hyperandrogenism), or check for hormonal imbalances that could affect fertility, menstrual cycles, or other health concerns.

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw if your test involves a fasting sample. Avoid smoking or consuming alcohol for at least 24 hours before testing.

During the test, a healthcare professional will draw blood from a vein in your arm. The blood sample is sent to a lab for analysis using a mass spectrometry method to measure free testosterone levels accurately.

Free testosterone results are not typically provided with specific reference ranges in all cases. Instead, they are often compared to your baseline levels or clinical context (e.g., symptoms, other hormone tests). Your provider will interpret the results in relation to your health needs.

High free testosterone levels may be linked to conditions like polycystic ovary syndrome (PCOS) in women or Cushing’s syndrome. Low levels could indicate hormonal deficiencies, aging, or certain medications. Always discuss results with your doctor.

Potential Health Implications

Abnormal free testosterone levels can affect various aspects of health, including bone density, muscle mass, mood, and reproductive function. For example, low testosterone may cause fatigue or reduced libido, while high levels could lead to acne or irregular menstrual cycles in women.