Prostate-specific antigen (PSA) blood test

Definition

Prostate-specific antigen (PSA) is a protein produced by prostate cells.

The PSA test is done to help diagnose and follow prostate cancer in men.

Alternative Names

Prostate-specific antigen; Prostate cancer screening test; PSA

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

Make sure your health care provider knows all the medicines you are taking. Some drugs cause your PSA level to be falsely low.

In most cases, no other special steps are needed to prepare for this test.

How the Test will Feel

You may feel slight pain or a prick when the needle is inserted. Afterward, there may be some throbbing or a slight bruise. These soon go away.

Why the Test is Performed

Reasons for a PSA test:

MORE ABOUT SCREENING FOR PROSTATE CANCER

Measuring the PSA level can increase the chance of finding prostate cancer when it is very early. But there is debate over the value of the PSA test for detecting prostate cancer. No single answer fits all men.

Before having the test, talk to your provider about the pros and cons of having a PSA test. Ask about:

If you choose to be tested, the PSA is most often done every year to screen men:

Normal Results

The PSA test result cannot diagnose prostate cancer. Only a prostate biopsy can diagnose this cancer.

Your provider will look at your PSA result and consider your age, ethnicity, medicines you are taking, and other things to decide whether your PSA is normal and whether you need more tests.

A normal PSA level is considered to be 4.0 nanograms per milliliter (ng/ml) of blood.

What Abnormal Results Mean

A high PSA level has been linked to an increased chance of having prostate cancer.

PSA testing is an important tool for detecting prostate cancer, but it is not foolproof. Other conditions can cause a rise in PSA, including:

Your provider will consider the following things when deciding on the next step:

Men at high risk may need to have more tests. These may include:

Other tests may also be done. The exact role of these tests in deciding on treatment is unclear.

If you have been treated for prostate cancer, the PSA level can show if treatment is working or if the cancer has come back. Often, PSA level rises before there are any symptoms. This may happen months or years beforehand.

Risks

Slight risks associated with having blood drawn may include:

References

Carter HB, Albertsen PC, Barry MJ, et al. Early detection of prostate cancer: AUA Guideline. J Urol. 2013;190(2):419-426. PMID: 23659877 www.ncbi.nlm.nih.gov/pubmed/23659877.

Morgan TM, Palapattu GS, Partin AW, Wei JT. Prostate cancer tumor markers. In: Wein AJ, Kavoussi LR, Partin AW, Peters CA, eds. Campbell-Walsh Urology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 108.

National Cancer Institute. Prostate cancer screening. (health professional version). Updated April 4, 2016. www.cancer.gov/types/prostate/hp/prostate-screening-pdq. Accessed April 13, 2016.

U.S. Preventive Services Task Force. Screening for prostate cancer. Updated July, 2015. www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/prostate-cancer-screening. Accessed April 20, 2015.



Review Date: 3/28/2016
Reviewed By: Scott Miller, MD, urologist in private practice in Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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