Definition of PSA:

PSA stands for prostate-specific antigen. It is a protein produced by prostate cells.

This article discusses the blood test to measure the amount of PSA in a man's blood. The PSA test is done to help diagnose and follow prostate cancer in men.

How the test is performed:

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

How to prepare for the test:

Men should not ejaculate for at least 48 hours before the PSA test is done. Doing so may cause a false rise in PSA levels.

Make sure your doctor knows all the medications you're taking. Some drugs may cause your PSA levels to be falsely low. These include finasteride, dutasteride, saw palmetto use, and antiandrogen drugs, such as flutamide, nilutamide, and bicalutamide.

No other special preparation is usually needed.

How the test will feel:

When the needle is inserted to draw blood, some people feel moderate pain while others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a bruise.

Why the test is performed:

Reasons for a PSA test:

• This test may be done to screen for prostate cancer.
• It is also used to follow patients after prostate cancer treatment to see if the cancer has come back.
• If a healthcare provider feels the prostate gland is not normal during physical exam

For information about prostate cancer screening, see the "Considerations" section below.