What is Testosterone?
Testosterone is the main male sex hormone (androgen), produced mostly in the testes in men and in smaller amounts by the ovaries and adrenal glands in women. A total testosterone test measures all testosterone in the blood both the portion bound to proteins and the small free fraction. It is the standard first-line marker for evaluating low libido, fatigue, infertility, and hormonal balance.
Why it matters
Testosterone regulates muscle mass, bone density, red blood cell production, fat distribution, mood, motivation, and sexual function. Levels decline gradually with age, and clinically low testosterone (hypogonadism) is linked to fatigue, depressed mood, reduced strength, and metabolic changes.
What it measures
Total concentration of testosterone in serum, ideally drawn in the morning (7–10 a.m.) when levels peak. Because much of it is bound to SHBG and albumin, total testosterone is often interpreted alongside SHBG and free testosterone.
Reference & optimal ranges
Reference ranges vary by lab, assay, age, and sex. The ranges below reflect commonly published adult intervals and are for education only always interpret results with the range printed on your own lab report and a clinician.
In men, high testosterone is uncommon and usually reflects supplementation, anabolic steroid use, or rarely a tumor. In women, elevated testosterone frequently points to PCOS.
Common symptoms
- Acne and oily skin
- Aggression or irritability
- In women: excess facial/body hair, irregular periods
- Testicular shrinkage (with exogenous use)
Potential causes
- Testosterone therapy or anabolic steroid use
- Polycystic ovary syndrome (PCOS)
- Congenital adrenal hyperplasia
- Androgen-secreting tumors (rare)
Low testosterone (male hypogonadism) becomes more common with age and with obesity, and can be primary (testicular) or secondary (pituitary/hypothalamic).
Common symptoms
- Low libido and erectile difficulty
- Fatigue and low motivation
- Loss of muscle mass and strength
- Depressed mood
- Increased body fat
- Reduced bone density
Potential causes
- Aging
- Obesity and metabolic syndrome
- Pituitary or hypothalamic dysfunction
- Testicular injury or disease
- Chronic illness, opioid use, or poor sleep
How to improve your Testosterone
Lifestyle
Reduce excess body fat
Adipose tissue converts testosterone to estrogen via aromatase; weight loss often raises testosterone in men with obesity.
Limit alcohol
Heavy alcohol intake suppresses testicular function and lowers testosterone.
Manage chronic stress
Sustained high cortisol suppresses the hypothalamic-pituitary-gonadal axis.
Nutrition
Adequate protein and healthy fats
Very low-fat diets can modestly lower testosterone; include mono- and polyunsaturated fats.
Correct zinc and vitamin D deficiency
Both are required cofactors for testosterone production; correct only if deficient.
Exercise
Resistance training
Compound lifting produces acute testosterone responses and long-term improvements in body composition.
Avoid chronic overtraining
Excessive endurance volume without recovery can suppress testosterone.
Sleep
Prioritize 7–9 hours
Most daily testosterone is produced during sleep; even one week of restriction to 5 hours can lower levels 10–15%.
Frequently asked questions
Scientific references
- Testosterone Therapy in Men With Hypogonadism: Clinical Practice Guideline The Endocrine Society, J Clin Endocrinol Metab (2018)
- Testosterone Levels Test MedlinePlus, U.S. National Library of Medicine
- Testosterone Testing.com
Educational information, not medical advice. This page is for general education and does not replace diagnosis or treatment by a licensed clinician. Do not start, stop, or change any medication, supplement, or treatment based on this content. Reference and optimal ranges vary between laboratories interpret your results with the range on your own report and a qualified professional.