Testosterone
Disclaimer: Information on this page is for educational purposes. Consult a physician to interpret your test results. Health Vault helps track biomarker trends but does not replace medical advice.
What This Test Measures
Testosterone is the primary androgen. In men, 95% comes from testes; in women from ovaries and adrenals.
Total testosterone includes bound and free fractions. Free testosterone is more accurate with altered SHBG.
Morning draw is required in men due to circadian variation.
Normal Ranges
| Group | Reference Range |
|---|---|
| Men | 250–1100 ng/dL total (8.64–29 nmol/L, morning) |
| Women | 15–70 ng/dL |
| Children | Age and sex dependent |
Reference ranges may vary by laboratory and assay method.
Causes of High Levels
- Polycystic ovary syndrome (women)
- Congenital adrenal hyperplasia
- Androgen-secreting tumors
- Anabolic steroids
Causes of Low Levels
- Male hypogonadism
- Aging
- Chronic illness
- Obesity
- Opioids, glucocorticoids
Test Preparation
- Morning draw 7–10 AM (men)
- Fasting preferred
- Report steroids and opioids
Related Biomarkers
| Biomarker | Relationship |
|---|---|
| Estradiol | Aromatization |
| Prolactin | Pituitary suppression |
| Thyroid Stimulating Hormone (TSH) | SHBG effects |
FAQ
How often should I take this test?
With hypogonadism symptoms — initial + 3–6 months on therapy.
What should I do if my result is abnormal?
Low T with symptoms — repeat morning sample; confirm before testosterone therapy.
Last updated: June 2026