Prostate-specific antigen

Introduction

PSA is an organ-specific enzyme produced by epithelial cells of the prostate. In healthy men, most PSA is secreted into seminal fluid liquifying semen, and only a small amount of it leaks into circulation. Normal PSA levels in the blood amount between 0-2.5 ng/ml. As a man ages, his prostate gets larger, leading to slightly higher normal levels of PSA.