A good, or normal, prostate-specific antigen score is 4.0 nanograms per milliliter and lower, according to the National Cancer Institute. PSA levels above this amount may be indicative of potential prostate cancer.
A PSA test measures the amount of prostate-specific antigen, a protein produced by the prostate gland, in a male’s blood, notes the National Cancer Institute. In cases where elevated levels are found, the treating doctor may recommend follow-up PSA testing at regular intervals to track potential changes over time. If levels continue to rise, the doctor may order additional testing, such as a urine sample, to confirm the initial findings or diagnose the problem. If the doctor suspects prostate cancer, he may order a prostate biopsy to confirm the diagnosis definitively.