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Why would I need this test?
Small amounts of prostate-specific antigen (PSA) are normally released into the bloodstream. Prostate-specific antigen is an enzyme made by the prostate gland of adult men. When the prostate is enlarged, infected, or diseased, larger amounts of PSA are released. Men with prostate cancer MAY have high levels of PSA. The level of PSA in the blood can be determined by a simple blood test. As with all tests, there are both false negatives and false positives, meaning that sometimes men with prostate cancer will have a negative test, and that sometimes men with a high PSA value will be found not to have prostate cancer.
The American Cancer Society recommends that men 50 years of age and older be screened annually for prostate cancer with both a digital rectal examination (DRE) and a PSA blood test. Men in high-risk groups, such as African-Americans, or those with a strong family history of prostate cancer, should consider being tested at 45 years of age. Other national organizations have other screening recommendations. The United States Preventive Services Task Force at this time does not recommend either for or against using this test as a routine screening test for prostate cancer. Some healthcare insurance providers do not cover the cost of PSA screening. If you are older than 50, or if you have a family history of prostate cancer, or if you are an African American man around the age of 40, you should discuss this test with your healthcare provider. Because of the controversy concerning screening, it's key for a man to discuss his risks with his doctor, and for them to discuss risks and benefits of screening techniques.
Testing for PSA can also be used to monitor the course of prostate cancer or monitor and evaluate a patient's response to treatment.
How do I prepare for this test?
No special preparation is needed for this test. In order to prevent a falsely elevated result, your doctor may recommend that you have the PSA test either prior to, or at least 48 hours after, a DRE.
How is this test performed?
A technician, doctor, or nurse will begin by using an antiseptic to clean the skin above a vein on your arm. A blood sample will then be drawn. You may feel a brief pricking sensation when the needle is initially inserted. The blood sample will be collected into a tube and then sent to a lab for analysis.
How long does the procedure take?
Obtaining blood for a PSA blood test takes between three and five minutes.
What happens if an abnormality is found?
If your PSA results are slightly elevated and the DRE was normal, your doctor may repeat the PSA test to see if it remains high.
An elevated PSA above 4 ng/mL (nanograms per milliliter) may indicate a 20 percent to 25 percent possibility of prostate cancer. If your PSA level is above 10 ng/mL, your chance of having prostate cancer is higher than 50 percent and increases further as your PSA level rises.
However, PSA results alone do not confirm a diagnosis of prostate cancer. Other conditions can cause elevated PSA levels. An enlarged prostate, a condition called benign prostate hyperplasia, can raise PSA levels two to three times higher than normal. An infected or inflamed prostate, and a biopsy or operation on the prostate, can also raise your PSA levels.
If your PSA results are high, further assessment and testing may include a transrectal ultrasound. A tissue biopsy is needed to make the diagnosis of prostate cancer.
Are there any risks associated with this test?
There are practically no risks associated with the blood test, itself. Although, there is always the concern that a false positive test might generate additional tests and anxiety. Alternatively, a false negative test might lead to delay in further evaluation for prostate cancer.
What is a desirable result?
Most men age 40 or older should have PSA levels under 4 ng/mL of blood. Ideally, PSA levels for men under age 40 should be less than 2.7 ng/mL.
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External Sources
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American Cancer Society Brochure
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American Cancer Society
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This article was reviewed and updated June 2007.
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