Prostate-Specific Antigen (PSA) Test
A prostate-specific antigen (PSA) test measures the amount of prostate-specific antigen in the blood. PSA is released into the blood by the prostate, which is part of the male reproductive system. Healthy people have low amounts of PSA in the blood. The amount of PSA in the blood normally increases as the prostate enlarges with age. PSA may increase because of inflammation of the prostate (prostatitis) or prostate cancer. An injury, a digital rectal exam, or sexual activity (ejaculation) may also briefly raise PSA levels.
Why It Is Done
The prostate-specific antigen (PSA) test is done to:
- Screen for prostate cancer. If your PSA level is higher than expected, your doctor may suggest other tests, including a prostate biopsy. This is because other common medical conditions, such as an enlarged prostate and prostatitis, can cause high PSA levels.
- 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.
- Follow up after prostate cancer treatment to watch for any signs of the cancer coming back. A PSA level that rises after radical prostatectomy or radiation therapy for localized prostate cancer may mean the cancer has returned or has spread.
How To Prepare
Do not ejaculate during the 2 days 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.
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.
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.
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.
Because normal PSA levels seem to increase with age, age-specific ranges may be used. But the use of age-specific ranges is controversial, and some doctors prefer to use one range for all ages. For this reason, it is important to discuss your test results with your doctor.
A PSA level within the normal ranges does not mean that prostate cancer is not present. Some men who have prostate cancer have normal PSA levels.
If your PSA level is high, your doctor may refer you to a urologist. What tests come next will depend on your overall health, your chances of having prostate cancer, and your feelings about having tests and treatments. You may have a repeat PSA test, an MRI, or tests that look at your risk for prostate cancer. Or you may be scheduled for a prostate biopsy.
Current as of: September 8, 2021
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Kathleen Romito MD - Family Medicine
Christopher G. Wood MD, FACS - Urology, Oncology