Age-Adjusted Lab Norms: Why Adult Reference Ranges Lie About Children and the Elderly
Age-Adjusted Lab Norms: Why Adult Reference Ranges Lie About Children and the Elderly A creatinine of 1.0 is normal in a 30-year-old. It’s kidney failure in a 5-year-old and possibly masked disease in a sarcopenic 85-year-old. Lab reference ranges printed on a report were derived from adult populations. They don't account for the physiology of a growing child or an aging body losing muscle mass. Applying adult normals to pediatric or geriatric patients leads to missed diagnoses, unnecessary workups, and false reassurance. This post covers the labs that change most dramatically by age and the clinical traps they create. The Big Offenders: Labs Where Age Changes Everything Lab Pediatric Shift Geriatric Shift Clinical Trap Creatinine Much lower in children (0.2–0.4 in infants, 0.3–0.7 in school-age). A cr of 1.0 = significant renal impairment in a child. Decreases with sarcopenia. A “normal” 1.0 may represent GFR of 40 in a frail elderly patient. Creatinine-based GFR overestimates k...