Free Testosterone (FT)

What is Free Testosterone?

Free testosterone is the small fraction of testosterone (1-3%) that circulates unbound to proteins in the blood. Unlike bound testosterone, free testosterone is immediately available to enter cells and exert hormonal effects, making it the most biologically active form.

Why is it Tested?

Doctors order free testosterone when total testosterone levels don’t correlate with symptoms, particularly when SHBG levels are abnormal. It’s essential for diagnosing hypogonadism, evaluating androgen excess in women, and monitoring hormone replacement therapy effectiveness.

Normal Ranges

Reference ranges vary by lab, age, and sex. General adult guidelines:

Men: 8.7–25.1 pg/mL
Women: 0.3–1.9 pg/mL

Free testosterone naturally declines with age in both sexes, though more gradually in women.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Free Testosterone

Low levels may indicate:

Hypogonadism (primary or secondary)
Age-related decline (andropause)
Chronic illness or stress
Medications affecting hormone production

High Free Testosterone

Elevated levels may suggest:

PCOS or androgen excess (in women)
Anabolic steroid use
Certain tumors
Congenital adrenal hyperplasia

How to Track Over Time

Free testosterone provides the most accurate picture of hormonal activity, especially when SHBG levels fluctuate. Tracking free testosterone helps distinguish between age-related decline and pathological deficiency, guides treatment decisions, and monitors therapeutic responses more precisely than total testosterone alone.

Free Testosterone