Schwartz Formula

Introduction

The Cockcroft-Gault equation is not used to estimate creatinine clearance in paediatric patient because it was developed using data from adults.

• Cockcroft-Gault equation is a formula developed from 249 patients aged 18 to 92 years old in a 1976 study.

NOTE: Recent guidelines are suggesting CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation as the preferred method for estimating adult GFR.

Schwartz Formula

In practice, we use Schwartz formula to estimate paediatric patient creatinine clearance.

• However, there is actually two variations.

The original Schwartz formula was developed using a cohort of children (n = 586) with normal renal function.

Estimated GFR (ml/min/1.73m²) = k × height (cm)/Serum creatinine (mg/dL)

• In the study, different values of the k coefficient according to age and sex were proposed to more accurately estimate GFR.
• Low birth weight ≤1 year = 0.33
• Full term ≤1 year = 0.45
• 1-13 years = 0.5
• 13-18 years female = 0.5
• 13-18 years male = 0.7

A recent re-examination by the original author (2009) found that a single k coefficient of 0.413 better estimates GFR in all children with CKD (age 1-16 years old).

NOTE: To convert the estimated GFR of Schwartz Formula from ml/min/1.73 m² to ml/min, you can multiply the value by the patient's body surface area and divide by 1.73.

Interpretation of Schwartz Formula

The interpretation of chronic kidney disease staging is based on the calculated value in ml/min/1.73 m².

• ≥90: Normal
• 60-89: Mild
• 45-59: Mild-moderate
• 30-44: Moderate-severe
• 15-29: Severe
• <15: End stage

External Links

• Prediction of creatinine clearance from serum creatinine, 1976
  
• A simple estimate of glomerular filtration rate in full-term infants during the first year of life, 1984
  
• New equations to estimate GFR in children with CKD, 2009
  
• Measurement and Estimation of Glomerular Filtration Rate in Children, 2017