Prostate-Specific Antigen (PSA)

Why It Is Done

The prostate-specific antigen (PSA) test is done to:

• Screen men for prostate cancer. Since other common medical conditions, such as benign prostatic hyperplasia (BPH) and prostatitis, can cause high PSA levels, a prostate biopsy may be done if your doctor is concerned about signs of prostate cancer.
• 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.
• Watch prostate cancer during active surveillance or other treatment. 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.

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 or prostate surgery in the past several weeks.
• Digital rectal exam 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 recently to drain urine.

Do not ejaculate for 24 hours before your PSA blood test, either during sex or masturbation.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).

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 on 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.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Recent sexual activity (ejaculation).
• Recent use of a tube (catheter) to drain urine or a cystoscopy.
• Recent urinary tract infection (UTI) or prostatitis.
• Recent digital rectal exam, prostate biopsy, or prostate surgery.
• Large doses of medicines, such as cyclophosphamide (Cytoxan) and methotrexate for cancer treatment.
• The medicines dutasteride (Avodart) and finasteride (Proscar), which are used to prevent further enlargement of the prostate gland in men who have BPH, or the type of finasteride (Propecia) that is used for male-pattern baldness.

What To Think About

• When combined with a digital rectal exam, the prostate-specific antigen (PSA) test may increase the chance of finding prostate cancer. To learn more, see the topic Digital Rectal Examination (DRE).
• Experts disagree about the type of testing that is appropriate if the PSA level is high. The decision may depend on:
  • Results of your digital rectal exam.
  • Results of any PSA tests you have had in the past. If your PSA level gets higher in a short amount of time, follow-up testing may be recommended.
  • Your age and health.
  • The costs and risks of more tests and treatments.
• Other prostate tests are being evaluated to determine how well they tell the difference between prostate cancer and benign prostatic hyperplasia.
  • The prostate-specific antigen density (PSAD) test compares the PSA value to the size of the prostate gland. The size of the prostate is measured using transrectal ultrasound (TRUS).
  • The PSA velocity test is a measure of how rapidly PSA levels increase over time. PSA levels increase more rapidly in men with prostate cancer and more slowly in men with prostate enlargement (benign prostatic hyperplasia).
  • A complexed prostate-specific antigen (cPSA) test may help show if a prostate biopsy should be done. This test measures the amount of several forms of PSA that are attached to proteins found in the blood.