Prostate-specific antigen (PSA) is a glycoprotein produced only by certain cells within the male prostate gland. Normally, very little PSA is secreted in the blood. Elevated levels of PSA have been associated with benign and malignant prostatic disorders and are considered as one of the markers for early detection of prostate cancer in men over 50 years. PSA exists in multiple forms, one where it is bound by a protein complex and another in free form. The presence of Total PSA alone is not sufficient for a proper analysis; therefore both the total and free forms are calculated. A ratio of total to free form PSA is used for the diagnosis.
