What is a prostate-specific antigen (PSA) test?

A prostate-specific antigen (PSA) test measures the level of PSA in your blood. The prostate is a small gland that is part of a man's reproductive system. It is located below the bladder and makes a fluid that is part of semen. PSA is a substance made by the prostate. Men normally have low PSA levels in their blood. A high PSA level may be a sign of prostate cancer, the most common non-skin cancer affecting American men. But high PSA levels can also mean noncancerous prostate conditions, such as infection or benign prostatic hyperplasia, a noncancerous enlargement of the prostate.

Other names: total PSA, free PSA

What is it used for?

A PSA test is used to screen for prostate cancer. Screening is a test that looks for a disease, such as cancer, in its early stages, when it's most treatable. Leading health organizations, such as the American Cancer Society and the Centers for Disease Control and Prevention (CDC), disagree on recommendations for using the PSA test for cancer screening. Reasons for disagreement include:

• Most types of prostate cancer grow very slowly. It can take decades before any symptoms show up.
• Treatment of slow-growing prostate cancer is often unnecessary. Many men with the disease live long, healthy lives without ever knowing they had cancer.
• Treatment can cause major side effects, including erectile dysfunction and urinary incontinence.
• Fast-growing prostate cancer is less common but more serious and often life-threatening. Age, family history, and other factors can put you at higher risk. But the PSA test alone can't tell the difference between slow- and fast-growing prostate cancer.

To find out if PSA testing is right for you, talk to your health care provider.

Why do I need a PSA test?

You may get a PSA test if you have certain risk factors for prostate cancer. These include:

• A father or brother with prostate cancer
• Being African-American. Prostate cancer is more common in African American men. The reason for this is unknown.
• Your age. Prostate cancer is more common in men over the age of 50.

You may also get a PSA test if:

• You have symptoms such as painful or frequent urination, and pelvic and/or back pain.
• You've already been diagnosed with prostate cancer. The PSA test can help monitor the effects of your treatment.

What happens during a PSA test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You will need to avoid having sex or masturbating for 24 hours before your PSA test, as releasing semen can raise your PSA levels.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruise at the spot where the needle was put in, but most symptoms go away quickly.