Prostate-specific antigen (PSA) is a substance released into a
man's blood by his prostate gland. A PSA test measures the amount of
prostate-specific antigen in the blood.
Low amounts of PSA may be found in the blood of healthy men. The
amount of PSA in the blood normally increases as a man's prostate enlarges with
age. It is also increased by ejaculation, inflammation of the prostate gland (prostatitis),
and by prostate cancer.
E. Gregory Thompson, MD - Internal Medicine & Christopher G. Wood, MD, FACS - Urology, Oncology