The PSA test is a blood test that is used to screen for the presence of prostate cancer. Prostate specific antigen is a protein found in the fluid portion of blood, called serum. PSA is specific to the prostate. No other human tissue or body part can make it. PSA levels can be measured in an individual's serum. With this information, doctors are able to screen for prostate cancer.
PSA is only present in men. PSA is present in all normal prostate tissue. The normal prostate cell holds onto most of the PSA. Very little leaks into the bloodstream. The small amount that leaks out is what is measured by the blood test. Prostate cancer cells actually have less PSA in each cell. However, the cancer cell tends to leak more PSA into the bloodstream. Knowing this fact, experts developed a range of expected values in patients with a normal prostate gland. The PSA value should be less than 4.0. This number reflects the belief that most men, roughly 95%, with normal prostate glands have a PSA value of 4.0 or less. (See below for age-specific normal values.) Almost any condition that affects the prostate can make the PSA rise.
The American Cancer Society and the American Urological Association recommend that men over age 50 have a yearly PSA. They should also have a rectal examination of the prostate. High-risk groups should begin screening at age 40 to 45. Men with a family history of the disease and African Americans fall into this category.
A simple blood test is all that is needed.