Prostate-specific antigen (PSA) is a protein produced by cells in the prostate gland. Free PSA refers to the proportion of PSA in the blood that is not bound to other proteins. Total PSA includes both free and bound forms. The ratio of free PSA to total PSA is often assessed to help interpret total PSA levels, particularly when they are in an indeterminate range. This measurement provides additional information that may assist in evaluating prostate health.
Free PSA
Free prostate antigen fraction.