Paediatrics
Schwartz eGFR (Paediatric)
Estimated GFR in children (bedside Schwartz).
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
The bedside Schwartz equation estimates the glomerular filtration rate (eGFR) in children and adolescents from their height and serum creatinine. It is based on the observation that GFR relates to body length and inversely to creatinine, using the form eGFR = k × height (cm) / creatinine (mg/dL). The 2009 updated equation uses a single constant, k = 0.413, derived from standardised (IDMS-traceable) creatinine assays. The result is reported in mL/min/1.73 m².
Interpreting the result
A result of 90 mL/min/1.73 m² or above is within the normal range for older children, 60–89 is mildly reduced, and below 60 indicates a more significantly reduced GFR. Because GFR matures during infancy and varies with age, paediatric normal ranges differ from adult cut-offs, particularly in the youngest children. The estimate is best used to track trends and to flag impairment for further assessment rather than as a precise single value.
Worked example
A child who is 120 cm tall with a serum creatinine of 0.5 mg/dL has an eGFR of 0.413 × 120 / 0.5 = roughly 99 mL/min/1.73 m², which is within the normal range.
Critical actions
Bedside Schwartz uses k = 0.413 with height in cm and creatinine in mg/dL (divide µmol/L by 88.4). Paediatric normal ranges vary with age.
Pearls / pitfalls
- Use the bedside constant k = 0.413 with height in cm and creatinine in mg/dL (divide a µmol/L value by 88.4).
- Ensure the creatinine assay is standardised (IDMS-traceable); using an old, non-standardised assay with k = 0.413 will mislead.
- Paediatric normal ranges vary with age, especially in infancy, so interpret against age-appropriate values.
- As with adults, the estimate is unreliable in rapidly changing creatinine or at extremes of muscle mass.
Evidence & validation
The updated bedside equation was derived and validated by Schwartz and colleagues using standardised creatinine in the CKiD study cohort of children with chronic kidney disease. It is the standard quick paediatric GFR estimate and is referenced in KDIGO and paediatric nephrology guidance.
Frequently asked questions
What constant does the bedside Schwartz equation use?
The 2009 updated bedside equation uses a single constant of 0.413, with height in centimetres and creatinine in mg/dL. This replaced the earlier age- and sex-specific constants used with older, non-standardised assays.
Why must the creatinine assay be standardised?
The k = 0.413 constant was derived using IDMS-traceable (standardised) creatinine. Applying it to a value from an older, non-standardised assay produces an inaccurate eGFR, so the assay type matters.
Are adult eGFR thresholds valid in children?
Not directly. GFR matures through infancy and varies with age, so paediatric normal ranges differ from the adult CKD-EPI cut-offs, particularly in young children.
How do I convert creatinine from µmol/L to mg/dL?
Divide the creatinine in µmol/L by 88.4 to obtain mg/dL. The bedside Schwartz equation requires creatinine in mg/dL and height in centimetres.
References
- Schwartz GJ, Muñoz A, Schneider MF, et al. New equations to estimate GFR in children with CKD. J Am Soc Nephrol. 2009;20(3):629–637.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
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