Pediatric GFR Calculator

Calculate the estimated glomerular filtration rate (eGFR) in children using the updated Schwartz equation to assess kidney function.

How to Use This Calculator

Enter the child's serum creatinine level in mg/dL
Enter the child's height in centimeters
Enter the child's age in years
Select the child's gender
Click Calculate to see the estimated GFR result

Formula Used

eGFR = (k × Height) / Serum Creatinine

Where:

k = Constant that varies with age and gender
Height = Child's height in centimeters
Serum Creatinine = Creatinine level in mg/dL

k values:

k = 0.33 for infants (< 1 year)
k = 0.413 for children (1-12 years)
k = 0.35 for adolescent females (13-18 years)
k = 0.48 for adolescent males (13-18 years)

Example Calculation

Real-World Scenario:

A pediatrician needs to assess kidney function in a 7-year-old boy who is being evaluated for a urinary tract infection.

Given:

Serum Creatinine = 0.6 mg/dL
Height = 120 cm
Age = 7 years
Gender = Male

Calculation:

For a 7-year-old child, k = 0.413

eGFR = (0.413 × 120) / 0.6

eGFR = 49.56 / 0.6

Result: eGFR = 82.6 mL/min/1.73m² (Normal range for this age)

Why This Calculation Matters

Clinical Applications

Diagnosing and monitoring kidney disease
Dosing medications that are renally excreted
Evaluating kidney function before and after surgery
Monitoring progression of chronic kidney disease

Key Benefits

Non-invasive assessment of kidney function
Standardized method for pediatric patients
Helps guide treatment decisions
Allows for longitudinal monitoring of kidney health

Common Mistakes & Tips

Ensure you're using the correct units: serum creatinine in mg/dL (not μmol/L) and height in centimeters (not inches or meters). Using incorrect units will lead to significantly inaccurate results.

The k value varies significantly based on age and gender. Using the wrong k value (e.g., using the infant value for a teenager) will result in inaccurate GFR estimation. Always ensure you're using the correct k value for the patient's age group.

GFR values should always be interpreted in the context of the patient's overall clinical picture. Factors like hydration status, medications, and acute illnesses can temporarily affect creatinine levels and thus the calculated GFR.

Frequently Asked Questions

Normal GFR values in children vary by age. Generally, full-term infants have a GFR of about 40-60 mL/min/1.73m², which increases to adult levels (approximately 100-130 mL/min/1.73m²) by around 2 years of age. Values below 60 mL/min/1.73m² may indicate kidney dysfunction.

The frequency of GFR monitoring depends on the severity and stability of the kidney condition. Children with stable chronic kidney disease may be monitored every 3-6 months, while those with acute or rapidly progressing conditions may need more frequent monitoring, sometimes as often as weekly or monthly.

This calculator is designed for children from infancy through adolescence (0-18 years). It uses different k values based on age groups to provide accurate estimates. However, for very premature infants or children with unusual body proportions, alternative methods may be more appropriate.

References & Disclaimer

Medical Disclaimer

This calculator is intended for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.

References

National Kidney Foundation: GFR Calculators - Information on GFR estimation in pediatric patients
Schwartz GJ, et al. "New equations to estimate GFR in children with CKD." J Am Soc Nephrol. 2009. - Original research on the updated Schwartz equation
National Institute of Diabetes and Digestive and Kidney Diseases: Estimating GFR - Clinical guidelines for GFR estimation

Accuracy Notice

The pediatric GFR calculator provides an estimate of kidney function based on the updated Schwartz equation. This estimate may be less accurate in children with extreme body proportions, malnutrition, obesity, or rapidly changing kidney function. For clinical decision-making, consider additional tests and consult with a pediatric nephrologist.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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