Testosterone, Free (Serum)

Why is this test important?

Free testosterone is crucial because it reflects the portion of testosterone that your body can use. Unlike total testosterone, which includes both free and bound forms, free testosterone directly influences reproductive and metabolic functions. Low levels may indicate hormonal imbalances, while high levels could signal conditions like polycystic ovary syndrome (PCOS) or Cushing’s syndrome in women, or other endocrine disorders in men.

What does it measure?

This test specifically measures the unbound (free) fraction of testosterone in your serum. Free testosterone is determined after separating it from proteins that normally bind to it, allowing for more accurate assessment of its biological activity.

How is the test performed?

A blood sample is drawn from a vein, typically in your arm. The sample is then processed to isolate and measure the free testosterone concentration using a sensitive immunoassay method, which detects the hormone’s presence with high precision.

What can affect results?

Several factors can influence free testosterone levels, including age, sex hormones, medications (such as steroids or birth control), chronic illnesses, and lifestyle choices like smoking or alcohol use. Stress, obesity, and certain medical conditions (e.g., thyroid disorders) may also play a role.