KRS (Kidney Recipient Specific)

Creatinine equation for adult kidney transplant recipients

Biomarkers
Creatinine
Validated for
Kidney transplant recipients, 18+ years
Inputs
Age, Sex, Creatinine
Reports
mL/min/1.73 m²
Published
2023

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

Formula

eGFR=e4.4275492−0.8230475ln⁡(Scr)−0.0124264⋅Scr2−0.0055068⋅age+0.1806494⋅male\text{eGFR} = e^{4.4275492 - 0.8230475 \ln(S_{cr}) - 0.0124264 \cdot S_{cr}^2 - 0.0055068 \cdot \text{age} + 0.1806494 \cdot \text{male}}

As text: eGFR = exp(4.4275492 − 0.8230475×ln(SCr) − 0.0124264×SCr² − 0.0055068×age + 0.1806494×[male]) [SCr in mg/dL]

Constants

SymbolMeaningValue
4.4275492Intercept
−0.8230475Coefficient for natural log of serum creatinine
−0.0124264Coefficient for squared serum creatinine
−0.0055068Age coefficient (per year)
MaleSex term
Male: +0.1806494
Female: 0
ScrS_{cr}Serum creatinine (input)mg/dL
AgePatient age (input)years

How it was developed

Developed in 3,622 adults who received a kidney transplant at Necker, Saint Louis or Toulouse hospitals in France between 2000 and 2021, with 8,827 GFR measurements; the main centre measured GFR by urinary ⁵¹Cr-EDTA clearance. It was externally validated in 11,867 recipients from 11 centres and three trials in Europe, the US and Australia.

Clinical notes

  • Main development centre: Jaffe creatinine before 2011, IDMS-traceable enzymatic after
  • Creatinine only; no cystatin C version was developed

Limitations

  • Not developed or validated in people with native kidneys
  • Not developed or validated in children
  • Underestimated measured GFR in several centres, especially at higher levels
  • Not validated in South American, Asian or African transplant centres

References

  1. Raynaud M, Al-Awadhi S, Juric I, et al. Race-free estimated glomerular filtration rate equation in kidney transplant recipients: development and validation study. BMJ. 2023;381:e073654. doi:10.1136/bmj-2022-073654

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