Estimate kidney function in children using the Schwartz formula.
eGFR = (k × Height in cm) / Serum Creatinine. The bedside Schwartz (2009) uses k=0.413 with enzymatic creatinine assays. Original constants: k=0.55 for children, 0.70 for adolescent males, 0.45 for LBW infants. The bedside formula is preferred with modern creatinine measurements. Normal pediatric GFR reaches adult levels (~120) by age 2.