Testosterone

A blood sample is taken from a vein. The best time for the blood sample to be taken is between 7 a.m. and 10 a.m. A second sample is often needed to confirm a result that is lower than expected.

Your health care provider may advise you to stop taking medicines that may affect the test.

You may feel a slight prick or sting when the needle is inserted. There may be some throbbing afterward.

This test may be done if you have symptoms of abnormal male hormone (androgen) production.

In males, the testicles produce most of the testosterone in the body. Levels are most often checked to evaluate signs of abnormal testosterone levels such as:

• Early or late puberty (in boys)
• Infertility, erectile dysfunction, low level of sexual interest, or thinning of the bones (in men)

In females, the ovaries produce most of the testosterone. The adrenal glands can also produce too much of other androgens that are converted to testosterone. Levels are most often checked to evaluate signs of higher testosterone levels in women, such as:

• Acne, oily skin
• Change in voice
• Decreased breast size
• Excess hair growth (dark, coarse hairs in the area of the moustache, beard, sideburns, chest, buttocks, inner thighs)
• Increased size of the clitoris
• Irregular or absent menstrual periods
• Male-pattern baldness or hair thinning

Normal measurements for these tests:

• Male age 17 to 50 years: 249 to 836 nanograms per deciliter (ng/dl), 8.6 to 29.0 nanomoles per liter (nmol/L)
• Male age over 50 years: 193 to 740 ng/dL, 6.7 to 25.7 nmol/L
• Female age 17 to 50 years: 8.4 to 48.1 ng/dL, 0.3 to 1.7 nmol/L
• Female age over 50 years: 2.9 to 40.1 ng/dL, 0.1 to 1.4 nmol/L

The examples above are common measurements for results for these tests. Normal value ranges may vary slightly among different labs. Some labs use different measurements or test different specimens. Talk to your provider about the meaning of your specific test results.

Certain health conditions, medicines, or injury can lead to low testosterone. The testosterone level also naturally drops with age. Low testosterone can affect sex drive, mood, and muscle mass in men.

Decreased total testosterone may be due to:

• Chronic illness
• The pituitary gland does not produce normal amounts of some or all of its hormones
• Problem with areas of the brain that control hormones (hypothalamus)
• Low thyroid function
• Delayed puberty
• Diseases of the testicles (trauma, cancer, infection, immune, iron overload)
• Benign tumor of the pituitary gland cells that produce too much of the hormone prolactin
• Too much body fat (obesity)
• Sleep problems (obstructive sleep apnea)
• Chronic stress from too much exercise (overtraining syndrome)

Increased total testosterone level may be due to:

• Resistance to the action of male hormones (androgen resistance)
• Tumor of the ovaries
• Cancer of the testes
• Congenital adrenal hyperplasia
• Taking medicines or drugs that increase testosterone level (including some supplements)

Serum testosterone

Aleksic S, Bartke A, Lamberts SWJ, Milman S. Endocrine function and aging. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 26.

Bulun SE, Babayev E. Physiology and pathology of the female reproductive axis. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 15.

Pitteloud N, Papadakis GE, Jacobs AN. Physiology and disorders of puberty. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 23.

Swerdloff RS, Wang C. The testis and male hypogonadism, infertility, and sexual dysfunction. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 216.

Updated by: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.