Does this test have other names?
Testosterone (total), serum testosterone
What is this test?
This test measures the level of the hormone testosterone in your blood. Testosterone is a male sex hormone (androgen) that helps male features develop. Testosterone is made in the testes and the adrenal glands. It causes the changes that occur in boys during puberty. Testosterone helps hair and muscles to grow. It also helps the penis and testes to grow. Testosterone also causes a boy's voice to deepen. Men continue to make testosterone. In adults it boosts sex drive and helps make sperm.
Women's ovaries also make small amounts of testosterone. It helps many organs and body processes in women.
The pituitary gland in your brain regulates the amount of testosterone your body makes.
Most of the testosterone in your blood attaches to two proteins: albumin and sex hormone binding globulin (SHBG). Some testosterone is not attached to proteins, or free. Free testosterone and albumin-bound testosterone are also referred to as bioavailable testosterone. This is the testosterone that is easily used by your body.
If your healthcare provider suspects that you have low or high testosterone, he or she will first test total testosterone levels. This looks at all three parts of testosterone. The free testosterone can help give more information when total testosterone is low.
Both men and women can have health problems because of low or high levels of testosterone. Women with high levels of testosterone may have polycystic ovary syndrome (PCOS). This condition marked by infertility, lack of menstruation, acne, obesity, blood sugar problems, and extra hair growth, especially on the face.
Testosterone levels in men drop as they age, but this is not considered to be hypogonadism. The FDA currently recommends against treating men with low testosterone caused only by aging.
Why do I need this test?
You may need this test if you have symptoms of low testosterone.
Symptoms of low testosterone in men include:
Low sex drive or lack of interest in sex
Difficulty getting an erection
Low sperm count and other fertility problems
Changes in the testicles
Loss of muscle mass
Symptoms of low testosterone in women include:
What other tests might I have along with this test?
Your healthcare provider may order other blood tests to check hormone levels. These include:
Follicle-stimulating hormone (FSH) test
Luteinizing hormone (LH) test
Thyroid stimulating hormone (TSH) test
You may also need to have:
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.
The results of this test are given in nanograms per deciliter (ng/dL). Normal test results show total testosterone levels of:
If your testosterone levels are lower than normal, you may have a condition that affects your testosterone production. If your testosterone levels are higher than normal, you may have a tumor on the testes or ovaries that affects your testosterone production.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your arm. This test is usually done in the morning, because testosterone levels tend to be highest at that time. But you may need to have this test more than once, and at different times of the day, to confirm low testosterone levels. This is because your testosterone level can change from morning to evening and from day to day.
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Some medicines may affect your test results. These include antifungal medicines such as ketoconazole and hormone medicines. Having the test done late in the day may show that your testosterone level is lower than it really is.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.