Testosterone Test

Why It Is Done

A testosterone test may be done to:

• See why a man is having problems in fathering a child (infertility). A low amount of testosterone can lead to low sperm counts.
• Check a man's sexual problems. Having a low level of testosterone may lower a man's sex drive or not allow him to have an erection (erectile dysfunction).
• See whether a high level of testosterone is causing a boy younger than age 10 to have early signs of puberty.
• Find out why a woman is developing male features, such as excessive facial and body hair (hirsutism) and a deep voice.
• Find out why a woman is having irregular menstrual periods.
• See if testosterone-lowering medicines are working in a man with advanced prostate cancer.
• Find the cause of osteoporosis in a man.

How To Prepare

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Your doctor may want you to do a morning blood test. That's because testosterone levels are highest between 7 a.m. and 9 a.m.

How It Is Done

A health professional uses a needle to take a blood sample, usually from the arm.

How It Feels

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

Risks

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Results

Your doctor will have your test results in a few days.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

• In men, a high level of testosterone may be caused by cancer of the testicles or adrenal glands.
• In boys younger than 10, a high level of testosterone may mean early (precocious) puberty, a tumor in the testicles, or an abnormal adrenal gland.
• In women, a high level of testosterone may be caused by cancer of the ovaries or adrenal glands or by polycystic ovary syndrome (PCOS). In rare cases, the part of the ovary that makes testosterone can become very sensitive to luteinizing hormone (LH), causing very high testosterone levels. This condition is called hyperthecosis.

Low values

• In men or boys who have gone through puberty, a low level of testosterone may be caused by a problem with the testicles, such as slow development of, an injury to, or a lack of testicles. It can also be caused from treatment with the female hormone estrogen, a problem with the pituitary gland, or many long-term (chronic) illnesses.
• A low testosterone level in men can also be caused by certain inherited diseases (such as Klinefelter syndrome or Down syndrome), liver disease (cirrhosis), or treatment for cancer of the prostate gland.
• Long-term (chronic) alcohol use can cause a low testosterone level.
• In women, a low level of testosterone may be caused by an underactive pituitary gland, Addison's disease, loss of ovary function through disease or surgery, and some medicines (such as corticosteroids or estrogen).
• Being very overweight, having long-term (chronic) pain, or taking some pain medicines can lower the level of sex hormone binding globulin (SHBG). This also decreases total testosterone level.