prostate specific antigen test

prostate specific antigen test A blood test that is used to screen for cancer of the prostate and to monitor treatment. Prostate specific antigen (PSA) is a protein that is produced by the prostate gland. If elevated levels of PSA are detected in the blood, additional testing is needed if it is being used as a screening measure. An elevated level of PSA is not specific to prostate cancer. Other diseases can cause elevated PSA, including benign prostatic hypertrophy (BPH), an increase in the size of the prostate that typically occurs with aging. Infection of the prostate gland (prostatitis) is another relatively common cause of elevated PSA. Many early cancers do not produce enough PSA to cause a significantly abnormal blood level. It is therefore important not to rely only on blood PSA testing. The most useful additional test is a physical prostate exam known as the digital rectal exam. See also digital rectal exam; prostate cancer; prostate gland; prostatic hyperplasia, benign.