Free Testosterone: A Guide
Free testosterone is the active form: reference ranges for men and women, causes of changes, PCOS, and monitoring.
Updated: 9/30/2026
Reference ranges (typical adult values)
| Who | Range | Unit |
|---|---|---|
| Men | 8.7 – 25.1 | pg/mL |
| Women | 0.3 – 1.9 | pg/mL |
Ranges differ between laboratories — the range printed on your own report always applies first.
What is free testosterone
Free testosterone is the unbound, biologically active form of testosterone in the blood. The vast majority of testosterone (around 98%) circulates bound to proteins — SHBG (sex hormone-binding globulin) and albumin. Only the remaining ~2% is free and able to act directly on cells.
This marker is especially useful when total testosterone is within normal range but symptoms suggest a possible testosterone deficiency or excess. Changes in SHBG levels can alter free testosterone without affecting total testosterone.
Reference ranges
Free testosterone reference ranges differ by sex:
- Men: 8.7–25.1 pg/mL
- Women: 0.3–1.9 pg/mL
Values can vary depending on age, time of day (highest in the morning), method, and laboratory. The range provided by your own laboratory takes precedence.
Why free testosterone may be elevated
Men:
- Exogenous testosterone (hormone therapy or anabolic steroids)
- Increased adrenal activity
- Low SHBG (due to obesity, insulin resistance, or certain medications)
Women:
- Polycystic ovary syndrome (PCOS): the most common cause of elevated testosterone in women
- Adrenal hyperplasia
- Low SHBG (due to obesity or insulin resistance)
Symptoms may include acne, increased hair growth (hirsutism), hair loss, and menstrual irregularities.
Why free testosterone may be low
Men:
- Age-related decline: testosterone decreases by approximately 1–2% per year after age 30
- Obesity: adipose tissue converts testosterone to estradiol
- Chronic stress and elevated cortisol
- High SHBG: due to liver disease, hyperthyroidism, or certain medications
- Hypogonadism: primary or secondary testicular dysfunction
- Sleep deprivation: even a few nights of inadequate sleep can significantly reduce testosterone
Women:
- Menopause and post-menopause
- Adrenal insufficiency
- Oral contraceptives (raise SHBG, lower free testosterone)
Next steps
1. Test alongside total testosterone, SHBG, and LH/FSH for a complete hormonal picture 2. If elevated in women — check DHEA-S, insulin, and glucose (PCOS workup) 3. If low in men — check prolactin, LH, FSH, and thyroid function 4. Review lifestyle factors: sleep, stress, physical activity, and body weight 5. Repeat the test in the morning (before 10 a.m.) — testosterone levels are highest in the morning
Monitoring over time
If values are normal and there are no symptoms, checking once a year is sufficient. If there are abnormalities or treatment is in progress, retest every 3–6 months until a stable level is reached.
Tracking trends helps distinguish natural age-related change from a faster-than-expected decline.
Questions to ask your doctor
- Could my symptoms be related to my free testosterone level?
- Should I also test SHBG to put free testosterone in context?
- Could my body weight and insulin resistance be affecting my testosterone?
- If I am planning a pregnancy, is my testosterone level normal?
- How often should I repeat this test?
*This is not medical advice. Consult your doctor for any health-related decisions.*