Prostate specific antigen (PSA) is a protein produced by cells of the prostate gland in men.  A man may have a PSA blood test measuring the level of PSA in a man’s blood with the results reported as nanograms of PSA per milliliter (ng/ml) of blood.  A normal PSA level is considered to be between 1.0 and 4.0 ng/ml.  If the number is above 4.0, the level is considered abnormal or elevated.