Optimal PSA value <1.0 ng/dL, though called normal up to 4.0 ng/mL. At 1.3 ng/ml (Avodart
Trial; most thorough done to date) prostate size, by ultrasound, has doubled young healthy values. If PSA < 1.0, prostate cancer
extremely rare. If elevated, consider https://www.accureference.com "Prostate Health Index" test for better guidance.