A PSA test is a blood test that measures the level of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate gland. Elevated levels of PSA in the blood can be an indication of prostate cancer, but other conditions such as an enlarged prostate or a prostate infection/inflammation can also cause an increase in PSA levels. It’s important to discuss with your doctor whether a PSA test is appropriate for you and how to interpret the results.