Testosterone

Definition

A testosterone test measures the amount of the male hormone, testosterone, in the blood. Both men and women produce this hormone.

The test described in this article measures the total amount of testosterone in the blood. Much of the testosterone in the blood is bound to a protein called sex hormone binding globulin (SHBG). Another blood test can measure the "free" testosterone. However, this type of test is often not very accurate.

Alternative Names

Serum testosterone

How the Test is Performed

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.

How to Prepare for the Test

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

How the Test will Feel

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

Why the Test is Performed

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 such as:

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, such as:

Normal Results

Normal measurements for these tests:

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

What Abnormal Results Mean

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:

Increased total testosterone level may be due to:

References

Chen Z, Legro RS, Ehrmann DA, Wei D. Androgen excess disorders in women. In: Robertson RP, ed. DeGroot's Endocrinology: Basic Science and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 124.

Haddad NG, Eugster EA. Endocrinology of pubertal disorders. In: Robertson RP, ed. DeGroot's Endocrinology: Basic Science and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 103.

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.



Review Date: 2/28/2024
Reviewed 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.
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