PSA stands for prostate-specific antigen, which is a protein produced by both normal and cancerous prostate cells. The PSA test is a blood test that measures the level of PSA in a sample of blood. The test is primarily used to screen for prostate cancer, but it can also help diagnose other prostate abnormalities. The results of the PSA test are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.

Its normal for all men to have some PSA in their blood, and a high level of PSA can be a sign of cancer, but it can also be raised in prostate conditions that are not cancer, such as an enlarged prostate or prostatitis. Therefore, determining what a high PSA score means can be complicated, and a diagnosis of prostate cancer is not made on a PSA level alone.

Most men without prostate cancer have PSA levels under 4 ng/mL of blood, and when prostate cancer develops, the PSA level often goes above 4. However, there is no specific cutoff point between a normal and an abnormal PSA level, and the reading varies from man to man and increases as they get older.

Doctors also check PSA levels during and after prostate cancer treatment to see how well the treatment is working. The PSA test is only one tool used to screen for early signs of prostate cancer, and its not clear if the benefits of prostate cancer screening outweigh the risks for most men. Therefore, its important to discuss the possible risks and benefits of having a PSA test with a doctor before deciding whether to be tested.