Prostate-Specific Antigen (PSA)

A prostate-specific antigen (PSA) test measures the amount of prostate-specific antigen in the blood. PSA is released into a man's blood by his prostate gland. Healthy men have low amounts of PSA in the blood. The amount of PSA in the blood normally increases as a man's prostate enlarges with age. PSA may increase as a result of an injury, a digital rectal exam, sexual activity (ejaculation), inflammation of the prostate gland (prostatitis), or prostate cancer.
Prostate cancer often grows very slowly, without causing major problems. Detecting prostate cancer early and treating it may prevent some health problems and reduce the risk of dying from the cancer. However, some treatments for prostate cancer can cause other problems, such as controlling urination (incontinence) or erection problems (erectile dysfunction). Some men may choose not to have a PSA test or treat prostate cancer if it is detected. For example, a man older than age 75 who has no bothersome symptoms of prostate cancer may choose not to treat the cancer if it is found, so he would not need a PSA test.
Why It Is Done
The prostate-specific antigen (PSA) test is done to:
    * Watch prostate cancer and see if treatment is working. If PSA levels increase, the cancer may be growing or spreading. PSA is usually not present in a man who has had his prostate gland removed. A PSA level that rises after prostate removal may mean the cancer has returned or has spread.
    * Check if cancer may be present when results from other tests, such as a digital rectal exam, are not normal. A PSA test does not diagnose cancer, but it can be used along with other tests to determine if cancer is present.
    * Check men for prostate cancer. Experts disagree on the usefulness of PSA testing as a screening tool for prostate cancer. If a PSA test is used for screening, it is usually done for men older than age 50 or for those at high risk for prostate cancer, such as men with a family history of prostate cancer, or for African-American men who have a higher chance of developing cancer than other men. Since other common medical conditions, such as prostatitis, can cause high PSA levels, a prostate biopsy is needed to confirm a diagnosis of cancer.

How To Prepare

Before you have a prostate-specific antigen (PSA), tell your doctor if you have had a:

    * Test to look at your bladder (cystoscopy) in the past several weeks.
    * Prostate needle biopsy in the past several weeks.
    * Prostate infection (prostatitis) or an urinary tract infection (UTI) that has not gone away.
    * Tube (catheter) inserted into your bladder to drain urine recently.
How It Is Done

The health professional taking a sample of your blood will:

    * Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
    * Clean the needle site with alcohol.
    * Put the needle into the vein. More than one needle stick may be needed.
    * Attach a tube to the needle to fill it with blood.
    * Remove the band from your arm when enough blood is collected.
    * Put a gauze pad or cotton ball over the needle site as the needle is removed.
    * Put pressure to the site and then a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
Risks
There is very little chance of a problem from having a blood sample taken from a vein.
    * You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
    * In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
    * Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.