Free Testosterone
Test Overview
The Free Testosterone test measures the amount of unbound (active) testosterone in the blood. Unlike Total Testosterone, which includes testosterone bound to proteins (SHBG and albumin), Free Testosterone represents the biologically active form that is available for the body to use. This test is particularly useful for assessing hormonal imbalances, sexual health, fertility, and conditions like hypogonadism or androgen excess.
Test Uses
- Diagnose low testosterone (hypogonadism) in men.
- Evaluate androgen excess in women (e.g., PCOS, hirsutism).
- Assess fertility and sexual function.
- Monitor testosterone therapy.
- Help diagnose pituitary or adrenal disorders.
Free Testosterone Test Results & Ranges
| Test Component: | Normal Range: | Abnormal (Possible Conditions) |
|---|---|---|
| Free Testosterone (Men) | 4.5 – 25.0 pg/mL | Low → Possible hypogonadism, aging, obesity, pituitary dysfunction. High → Possible testosterone therapy effects, tumors, anabolic steroid use. |
| Free Testosterone (Women) | 0.1 – 6.4 pg/mL | High → Possible PCOS, adrenal tumors, hirsutism, or excessive androgen production. Low → Possible low ovarian function, menopause, or pituitary dysfunction. |
- Lower Free Testosterone may indicate aging, obesity, or chronic illness.
- Higher Free Testosterone may suggest excess androgen production, adrenal disorders, or steroid use.
Expected Turnaround Time
- Results Available: Typically within 24 – 48 hours.
Specimen Requirements
- Sample Type: Blood sample (venipuncture).
- Container: Serum separator tube (SST, gold or red-top tube).
Collection Instructions
- Fasting: Not required, but morning collection (before 10 AM) is recommended due to daily testosterone fluctuations.
- Avoid strenuous exercise or stress before the test, as these may impact levels.
Test Details
Clinical Use: The Free Testosterone test is often ordered alongside Total Testosterone, SHBG (Sex Hormone-Binding Globulin), and LH (Luteinizing Hormone) to get a complete picture of testosterone status. Useful in diagnosing hormonal imbalances affecting sexual health, energy levels, muscle mass, and mood.
Limitations: Testosterone levels naturally decline with age. Additional hormone testing may be required to determine the root cause of abnormalities.
The Free Testosterone test is crucial for assessing hormonal balance, diagnosing reproductive issues, and monitoring testosterone therapy, providing insight into the body’s active androgen levels.