CKiD U25

Chronic Kidney Disease in Children study

Creatinine–height equation for children and young adults with CKD

Biomarkers
Creatinine
Validated for
1–25 years
Inputs
Age, Sex, Height, Creatinine
Reports
mL/min/1.73 m²
Published
2021

The eGFR guide explains which equation the calculator suggests and indexed and absolute GFR.

Formula

eGFR=κ×heightScr where κ varies by sex and age\text{eGFR} = \kappa \times \frac{\text{height}}{S_{cr}} \text{ where } \kappa \text{ varies by sex and age}

As text: eGFR = κ × (height/SCr) where κ varies by sex and age

Constants

SymbolMeaningValue
κ\kappaAge- and sex-dependent coefficient (Female)
Age 1 to <12: 36.1 × 1.008^(age − 12)
Age 12 to <18: 36.1 × 1.023^(age − 12)
Age 18–25: 41.4
κ\kappaAge- and sex-dependent coefficient (Male)
Age 1 to <12: 39.0 × 1.008^(age − 12)
Age 12 to <18: 39.0 × 1.045^(age − 12)
Age 18–25: 50.8
HeightPatient height (input)meters
ScrS_{cr}Serum creatinine (input)mg/dL

How it was developed

Developed in the CKiD Study, a cohort of children and young adults aged 1 to 25 years with mild to moderate CKD recruited at 63 sites in the United States and Canada. Training used 1,764 measurements from 618 participants, with GFR measured by plasma iohexol disappearance; 891 measurements from 310 other participants formed the internal validation set.

Clinical notes

  • No jump in eGFR at the transition from adolescence to adulthood
  • Built on enzymatic creatinine measured at one central laboratory
  • Cited as a validated eGFRcr equation for children in KDIGO 2024

Limitations

  • Derivation cohort did not include people without CKD
  • Performance uncertain in very young children and at very low GFR
  • Muscle mass unusual for height, as in muscle wasting, affects the estimate

References

  1. Pierce CB, Muñoz A, Ng DK, Warady BA, Furth SL, Schwartz GJ. Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease. Kidney Int. 2021;99(4):948-956. doi:10.1016/j.kint.2020.10.047
  2. Ng DK, Pierce CB. Kidney disease progression in children and young adults with pediatric CKD: Epidemiologic perspectives and clinical applications. Semin Nephrol. 2021;41(5):405-415. doi:10.1016/j.semnephrol.2021.09.002

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