Prostate Specific Antigen (PSA)

Prostate-specific antigen, or PSA, is a protein produced by normal, as well as malignant, cells of the prostate gland. The PSA test measures the level of PSA in a man’s blood. For this test, a blood sample is sent to a laboratory for analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.

A prostate-specific antigen (PSA) test measures the level of PSA in a man’s blood. PSA is a protein produced by the cells of your prostate, a small gland just underneath your bladder. PSA circulates through your entire body at low levels at all times. A PSA test alone doesn’t provide enough information for your doctor to make a diagnosis. However, your doctor can take the results of a PSA test into consideration when trying to decide whether your symptoms and test results are due to cancer or another condition.

All men are at risk of prostate cancer, but a few populations are more likely to develop it. These include:

• Older men
• African-American men
• Men with a family history of prostate cancer

In addition to testing for prostate cancer, your doctor may also order a PSA test:

• To determine what’s causing a physical abnormality on your prostate found during a physical exam
• To help decide when to begin treatment, if you’ve been diagnosed with prostate cancer
• To monitor your prostate cancer treatment

A PSA test is sensitive and can detect higher-than-average levels of PSA. High levels of PSA may be associated with prostate cancer before any physical symptoms appear. However, high levels of PSA may also mean you have a noncancerous condition that’s increasing your PSA levels.

Drawing blood is considered safe. However, because veins and arteries vary in size and depth, getting a blood sample isn’t always simple. The healthcare provider who draws your blood may have to try several veins in multiple locations on your body before they find one that allows them to get enough blood.

Drawing blood also has several other risks. These include risk of:

• Fainting
• Excessive bleeding
• Feeling lightheaded or dizzy
• An infection at the puncture site
• A hematoma, or blood collected under the skin, at the puncture site

If your PSA levels are elevated, you’ll likely need additional tests to learn the cause. Other than prostate cancer, possible reasons for a rise in PSA include:

• A recent insertion of a catheter tube into your bladder to help drain urine
• Recent testing on your bladder or prostate
• A urinary tract infection