LAB TEST
Testosterone
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.
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: Early or late puberty (in boys) Infertility, erectile dysfunction , low…
Normal Results
Normal measurements for these tests: Male: 300 to 1,000 nanograms per deciliter (ng/dL) or 10 to 35 nanomoles per liter (nmol/L) Female: 15 to 70 ng/dL or 0.5 to 2.4 nmol/L The examples above are common measurements for results for these tests. Normal value ranges may vary slightly among different laboratories. Some…
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: Chronic illness The pituitary gland does not produce normal amounts of…
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:…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 28/02/2024).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.