Prostate-Specific Antigen (PSA)

PSA

This test measures the level of prostate-specific antigen (PSA) in your blood.

The cells of the prostate gland make the protein called PSA. Males normally have low levels of PSA. If your PSA levels start to rise, it could mean you have one of the below:

• Prostate cancer

• A benign prostate condition

• Inflammation of the prostate

• An infection in the prostate

Experts don’t all agree on when to have PSA testing:

• The U.S. Preventative Services Task Force advises males who don't have any symptoms of prostate cancer not to have a PSA test. You can still have the test if you want it after your provider has explained the benefits and risks of the test. The task force says that PSA test results can lead to treating small cancers that would never be life-threatening.

• The American Cancer Society advises that males be told the risks and benefits of PSA testing and make their own decision with their healthcare provider about if and when to be screened.

• The American Urologic Society says that PSA screening is most helpful between the ages of 55 and 69. The decision to be screened should be made by you after discussing the risks and benefits with your healthcare provider. Routine screening is not advised for males younger than 40. If you have a brother or father with prostate cancer or you are African American, you may be advised to start testing at age 40.

You may need this test if you are age 50 or older and your healthcare provider wants to screen you for prostate cancer. Some providers advise screening at age 40 or 45 if you have a family history of prostate cancer or other risk factors.

You may also have this test if you have already been diagnosed with prostate cancer. This is so your healthcare provider can check your treatment and see if your cancer has come back.

Your healthcare provider may also do a digital rectal exam (DRE). A DRE is a physical exam of the prostate, not a lab test. For the exam, your provider will place a gloved finger in your rectum and feel the prostate to check the size and for any bumps or abnormal areas.

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in nanograms per milliliter, ng/mL. 

Results below 4.0 ng/mL are seen as normal. But some healthcare providers may use these age-based results brackets to define normal for you: 

• Ages 40 to 49: 0–2.5 ng/mL

• Ages 50 to 59: 0–3.5 ng/mL

• Ages 60 to 69: 0–4.5 ng/mL

• Ages 70 to 79: 0–6.5 ng/mL

A rising PSA may mean that you have cancer. But the PSA results alone won't tell your healthcare provider if it's cancer or a benign prostate condition. If your healthcare provider thinks you could have cancer, you may need a biopsy of the prostate to confirm the diagnosis.

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

Test results can be affected by:

• An infection

• Some medicines

• Riding a bike before the test

• Ejaculation before the test

You may be told not to have sex or ride a bike 1 to 2 days before the test. In addition, be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.