Prostate-specific antigen, or PSA, levels may rise due to prostate cancer, inflammation of the prostate, a urinary tract infection or an enlarged prostate, explains the National Cancer Institute. The PSA blood test is often done in conjunction with a digital rectal exam.
High prostate-specific antigen levels occur in men with prostate cancer, but high levels do not necessarily mean a man has cancer, according to the National Cancer Institute. Most doctors consider PSA levels of 4.0 nanograms per millimeter or lower to be normal. When PSA levels rise above this number, a doctor may test the patient's PSA levels again and carefully monitor PSA levels over time with frequent testing.