EKFC (European Kidney Function Consortium)

Full age spectrum creatinine equation for children and adults

Biomarkers
Creatinine
Validated for
2+ years
Inputs
Age, Sex, 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=107.3×(Scr/Q)α×{1if age≤400.990age−40if age>40\text{eGFR} = 107.3 \times (S_{cr}/Q)^{\alpha} \times \begin{cases} 1 & \text{if age} \leq 40 \\ 0.990^{\text{age}-40} & \text{if age} > 40 \end{cases}

As text: eGFR = 107.3 × (SCr/Q)^α × [0.990^(Age-40) if Age>40]; α = -0.322 if SCr/Q < 1, α = -1.132 if SCr/Q ≥ 1

Constants

SymbolMeaningValue
107.3Base coefficient
QQMedian serum creatinine of healthy persons (rescaling factor)
Female (>25 y): 0.70 (62 µmol/L)mg/dL
Male (>25 y): 0.90 (80 µmol/L)mg/dL
2–25 y: ln(Q) polynomial in age (Pottel 2021, Figure 1)mg/dL
α\alphaExponent (depends on SCr/Q ratio)
SCr/Q < 1: −0.322
SCr/Q ≥ 1: −1.132
Age factorAge correction applied only when age > 40
Age ≤ 40: 1 (no correction)
Age > 40: 0.990^(age − 40)
ScrS_{cr}Serum creatinine (input)mg/dL
AgePatient age (input)years

How it was developed

Developed in 11,251 children and adults from 7 of the 13 research and clinical cohorts pooled for the study, split at random into development (8,473) and internal validation (2,778) sets; the final coefficients were fitted on both combined. GFR was measured as plasma or urinary clearance of iohexol, inulin, ⁵¹Cr-EDTA or iothalamate.

Clinical notes

  • Modified FAS equation combining design features of FAS and CKD-EPI
  • Continuous across the age range, with no jump at age 18
  • Developed with IDMS-traceable serum creatinine assays
  • Uses European non-Black Q values; Black European and African Q values are published

Limitations

  • Developed and validated in White populations only; no Black participants
  • Overestimates GFR with low muscle mass, e.g. anorexia, paralysis, malnourishment
  • Underestimates GFR in children under 5
  • Effect of proteinuria or hypoalbuminaemia on accuracy was not evaluated

References

  1. Pottel H, Björk J, Courbebaisse M, et al. Development and validation of a modified full age spectrum creatinine-based equation to estimate glomerular filtration rate. Ann Intern Med. 2021;174(2):183-191. doi:10.7326/M20-4366
  2. Delanaye P, Cavalier E, Pottel H, Stehlé T. New and old GFR equations: a European perspective. Clin Kidney J. 2023;16(9):1375-1383. doi:10.1093/ckj/sfad039

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