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
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
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
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.