Pediatric eGFR: Schwartz Formula for Children's Kidney Function
Children are not small adults — and that is especially true for kidney function. The standard CKD-EPI 2021 equation is validated for adults aged 18 and older, so it must not be used for children. Instead, pediatric kidney function is estimated with the Schwartz formula, which accounts for a child's height and changing muscle mass. This article explains how it works and what caregivers should know.
For adults, use our eGFR calculator; for anyone under 18, consult a pediatric clinician and use the pediatric tool.
Why children need a different equation
A child's body is still developing: muscle mass, body size, and creatinine production all change with growth. An adult equation that uses only creatinine, age, and sex would seriously misjudge a child's kidney function. Pediatric formulas add height — a close proxy for the muscle mass expected at a given age — to correct for this.
The Bedside Schwartz formula
The most widely used pediatric equation is the updated Bedside Schwartz formula:
eGFR = 0.413 × (height in cm / serum creatinine in mg/dL)
It is designed for children and adolescents roughly aged 1 to 18. The result is expressed in mL/min/1.73 m², just like the adult eGFR, so the general stage framework is similar — but the calculation is entirely different.
How to use it
- Obtain the child's serum creatinine (in mg/dL) from a blood test.
- Measure height in centimeters.
- Compute 0.413 × (height ÷ creatinine).
- Interpret alongside age-specific normal ranges and urine testing.
| Step | Example value |
|---|---|
| Serum creatinine | 0.5 mg/dL |
| Height | 120 cm |
| Calculation | 0.413 × (120 ÷ 0.5) |
| eGFR | About 99 mL/min/1.73 m² |
A pediatric nephrologist should always interpret the result in context, because normal values vary with age and size.
Other pediatric equations
Beyond Bedside Schwartz, several formulas exist for special situations:
- Full Schwartz (2009) and CKiD (Creatinine + cystatin C) equations — more precise, used in specialized centers or research.
- Neonatal formulas for newborns, where physiology differs greatly.
- Cystatin C-based equations — useful when creatinine is unreliable.
When to evaluate a child's kidney function
Pediatric kidney assessment is typically needed for:
- Congenital kidney or urinary tract abnormalities.
- Recurrent urinary tract infections.
- Diabetes or hypertension in childhood.
- Genetic conditions affecting the kidneys.
- Monitoring after certain treatments or medications.
Adults should never apply the adult eGFR to a child's lab values — the numbers will be misleading. For more on the adult side, see how to calculate eGFR and CKD-EPI 2021 vs MDRD.
Working with your pediatric care team
Kidney care in children is a team effort that often involves a pediatrician, pediatric nephrologist, renal dietitian, and sometimes a urologist. After an eGFR estimate with the Schwartz formula, the care team interprets it alongside urine tests, blood pressure, growth charts, and imaging — because a single number rarely tells the whole story in a growing child. For chronic conditions, expect regular monitoring timed to the child's stage of kidney function and growth. Parents can help by keeping a record of lab values, heights, and medications, and by asking how results compare with age-specific normal ranges rather than adult cutoffs. Early detection of congenital or acquired kidney issues, combined with timely referral to a specialist, can dramatically improve long-term outcomes — which is why using the correct pediatric equation, rather than an adult one, matters so much.
Frequently asked questions
Can I use the adult eGFR calculator for my child? No. Children require the Schwartz formula (or a similar pediatric equation). The adult CKD-EPI equation is not valid below age 18.
What is a normal pediatric eGFR? Normal values are generally high in children (often above 90) and vary with age. A pediatric nephrologist should interpret results against age-appropriate references.
Is the Schwartz formula accurate? The Bedside Schwartz formula is reasonably accurate for clinical use in children 1–18. For greater precision, specialized centers may use cystatin C or the CKiD equation.
Questions to ask your child's doctor
At a kidney appointment, useful questions include: Which formula was used to estimate my child's eGFR? How does the result compare with age-based normal ranges? Is there protein or blood in the urine? Could any medication, supplement, or recent illness be affecting the number? How often should we recheck? Bringing the child's recent growth measurements and a full list of medications helps the care team give precise, individualized answers and a clear follow-up plan.
Bottom line
Pediatric kidney function uses the Schwartz formula, not the adult eGFR equation, because growth and changing muscle mass demand a height-based calculation. For anyone under 18, work with a pediatric clinician and use the correct pediatric tool. Adults can estimate their own kidney function with our free eGFR calculator, and learn more in the blog and FAQ.
This article is for educational purposes only and is not medical advice. Always consult a qualified pediatric healthcare professional — and ideally a pediatric nephrologist — for a child's kidney evaluation.