What it is
The bedside Schwartz equation estimates glomerular filtration rate (eGFR) in children and adolescents from serum creatinine and height. It is the most widely used pediatric eGFR estimate for staging chronic kidney disease and tracking renal function over time.
The formula
$$ eGFR\ (mL/min/1.73m^2) = \frac{k \times height\ (cm)}{serum\ creatinine\ (mg/dL)} $$
The updated 2009 “bedside” Schwartz constant is k = 0.413, derived in a CKD cohort using enzymatic, IDMS-traceable creatinine assays. This replaced the older constants (0.55 for children, 0.45 for term infants, 0.7 for adolescent males) that were calibrated to the now-largely-obsolete Jaffe method.
If creatinine is reported in µmol/L, convert: divide by 88.4 to get mg/dL (or use k = 36.5 with height in cm and creatinine in µmol/L).
When to use it
Use it for routine GFR estimation in children roughly 1–18 years with stable renal function. For CKD staging, trend monitoring, and dose-adjustment screening, it is a practical bedside tool that needs only height and a creatinine value.
Worked example
A child, height 100 cm, serum creatinine 0.4 mg/dL:
$$ eGFR = \frac{0.413 \times 100}{0.4} = 103\ mL/min/1.73m^2 $$
A normal estimate for a young child.
Pitfalls and caveats
- Assay calibration is critical. k = 0.413 is valid only for enzymatic / IDMS-standardized creatinine. Using it with an uncalibrated Jaffe assay overestimates GFR.
- Not validated in neonates and young infants (the cohort was children with CKD ≥1 year). Use cystatin C-based or other neonatal methods there.
- Unreliable at extremes of muscle mass — malnutrition, neuromuscular disease, amputees, or unusually muscular adolescents — because creatinine generation is non-standard.
- Steady state only. In acute kidney injury or rapidly changing creatinine, no creatinine-based estimate is valid.
- Height must be a true standing/recumbent length, not parent-reported.
- For greater accuracy, consider the combined creatinine–cystatin C (“Schwartz-Lyon” or CKiD U25) equations, or measured GFR when management hinges on a precise value.
Run it now: Schwartz eGFR Calculator
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.