The prostate-specific antigen blood test (PSA test) is a screening test. It measures the amount of prostate-specific antigen (PSA) in a man's blood.
PSA is a chemical made by the prostate. The prostate is a sex gland located near a man's bladder. It produces the fluid in semen.
PSA levels normally increase as a man ages. But a higher-than-normal PSA level can be one clue that cancer has developed in the prostate gland.
However, high levels of PSA also can be found in other conditions that are noncancerous. These include prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH), an enlargement of the prostate that affects many older men.