Pediatric GFR Calculator

What is the Schwartz Formula?

The Schwartz formula is the clinical standard for estimating Glomerular Filtration Rate (eGFR) in the pediatric population. It estimates kidney function by correlating serum creatinine with the patient's height.

This calculator uses the **Bedside Schwartz Equation (2009)**: $$eGFR = (k \times Height_{cm}) / Creatinine_{mg/dL}$$. The constant ($k$) varies based on the patient's physiological development.

Infants vs. Children Calculation

Renal function is not fully mature at birth. For infants under 1 year of age, this calculator automatically applies a constant ($k = 0.33$) to account for lower muscle mass and immature filtration. For children and adolescents (1-18 years), the standard $k = 0.413$ is used.

Original (1976) vs. Bedside (2009) Schwartz

Modern laboratories use **IDMS-traceable** creatinine methods. The original 1976 formula used higher $ values ($0.55$ or $0.70$) which are now obsolete. Using the old constants with modern lab results would lead to an overestimation of kidney function. This calculator adheres to the 2009 Bedside standard (=0.413$).

Pediatric eGFR Stages

When to use this calculator?

• Staging Chronic Kidney Disease (CKD) in pediatric patients.
• Dosing of renal-cleared medications (e.g., Vancomycin, Aminoglycosides).
• Monitoring renal function in children with congenital anomalies of the kidney.

Limitations

The Schwartz formula may not be accurate in cases of Acute Kidney Injury (AKI), severe malnutrition, or in patients with significantly abnormal muscle mass (e.g., muscular dystrophy).