The laboratory test for prostate specific antigen (PSA) is a blood test that measures the levels of a specific protein in the blood that is produced by the prostate gland. A high PSA result may indicate prostatitis, enlarged prostate or prostate cancer.
Levels
A PSA number under 4 nanograms per milliliter (ng/mL) is considered normal. The higher the PSA number, the higher the risk of prostate cancer.
Benefits
The results of a PSA test help the physician diagnose a prostate condition and, with the patient, decide on a course of treatment.
Time Frame
Men with a family history of prostate cancer should start yearly testing at age 45; those with no medical history should start testing at age 50.
Significance
Early diagnosis based on the results of a PSA test can rule out or improve chances of survival from prostate cancer. Rising PSA levels following prostate removal may indicate recurrence of cancer.
Warning
Because ejaculation causes a temporary rise in PSA blood levels, sexual activity just prior to taking a PSA test can interfere with the results.
