Testosterone Levels Test

A testosterone levels test measures the amount of the hormone testosterone in a sample of your blood. Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs. Though often considered a male sex hormone, testosterone is present in females in smaller amounts.

In both sexes, testosterone helps control your sex drive and helps with muscle and bone growth. In males, it is also involved in Body hair growth.; A deepening voice during puberty.; The production of sperm.; The making of new red blood cells.; An increase in height.; All the testosterone in your blood is either bound to proteins or unbound (free). Free testosterone is more available for your body to use when building bones and muscles.

However, most of your testosterone is bound to proteins such as sex-hormone-binding globulin (SHBG) and albumin. When testosterone is bound, your body can't use it as easily. This is necessary for your health.

Having most of your testosterone bound to proteins makes sure your body doesn't use too much. Your health care provider can measure your testosterone levels by ordering one of three tests. These are: A total testosterone test, which measures both bound and free testosterone.

This is the most common type of test.; A free testosterone test, which measures only the unattached form of testosterone. This test is less common, but it may help your provider diagnose certain medical conditions.; A bioavailable testosterone test, which measures free testosterone and testosterone that's attached to proteins other than SHBG. This test isn't commonly done, but like a free testosterone test, it may help diagnose certain medical conditions.;

Why this test is done

You may need this test if you have symptoms of abnormal testosterone levels.

For males who have gone through puberty, the test is mostly used for symptoms of low T levels (testosterone levels which are too low).

The symptoms of low T may include:

• Low sex drive.
• Erectile disfunction or "ED" (difficulty getting or keeping an erection).
• Infertility (difficulty getting someone pregnant).
• Enlarged breasts.
• Lack of face or body hair.
• Thinning bones or anemia without a known cause.
• Loss of muscle mass.

For females, the test is mostly used for symptoms of high T levels.

Symptoms of high T may include:

• Abnormal hair growth on the body or face.
• Hair loss on the head that may be like male-pattern baldness (hair loss at the temples and balding on the top of the head).
• Voice changes.
• Irregular or no menstrual periods.
• Infertility (difficulty getting pregnant).
• Acne.

How to prepare

In certain cases, you may need to fast (not eat or drink) for several hours before the test. You may also need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

Ask your provider how you should prepare for a testosterone levels test.

Sample type

Blood

Other names for this test

serum testosterone, total testosterone, free testosterone, bioavailable testosterone