Why reference ranges vary between labs and age groups—population statistics, assay differences, and why This page is part of the Male Health hub on Evidence Before Claims. Content is for educational purposes only and is reviewed against peer-reviewed studies, FDA labeling, and current clinical guidelines. It does not provide diagnosis, treatment, or individualized medical advi
Reviewed by Sarah Chen, MD (illustrative reviewer) — MD, Internal Medicine. Last reviewed: May 2026. Educational content only; not medical advice.