For men in their 40s and 50s: A PSA score greater than 2.5 ng/ml is considered abnormal. The median PSA for this age range is 0.6 to 0.7 ng/ml. For men in their 60s: A PSA score greater than 4.0 ng/ml is considered abnormal. Prostate gland Enlarge image The PSA test is a blood test used primarily to screen for prostate cancer. The test measures the amount of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate, a small gland that sits below the bladder in males. cytcr.