Clinical reference ranges for biomarkers are derived from population averages that include metabolically unhealthy individuals, which results in the pathologization of normal physiological variation and the obscuring of true deficiency states.

Study: Serum IGF-1 and IGFBP-3 levels in healthy Korean men aged 19–40 years: a cross-sectional analysis of reference ranges and seasonal variation

This study found that even healthy young men have different levels of certain body chemicals depending on the season, which means using one standard number for everyone might make normal differences look like problems. That supports the idea that current medical ranges are too broad and miss real health issues.

Study: Early warning system for player recovery? A series of case studies illustrating the application of individualised adaptive reference ranges in the longitudinal blood monitoring of English Premier League soccer players

Doctors usually compare your blood test results to what's average for most people, but this study shows that’s not always accurate—your body’s normal is different from someone else’s. Using your own past results as a baseline helps spot real problems better than comparing you to a crowd.