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  6. Glomerular Filtration Rate Equations
  7. eGFR Equations for Adults
  8. Previous eGFR Equations for Reference

Previous eGFR Equations for Reference

Glomerular filtration rate (GFR) estimating equations that include a race coefficient are provided for reference purposes only.

NIDDK supports the National Kidney Foundation–American Society of Nephrology Task Force’s recommendation to calculate estimated GFR (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimating equations that do not include a race coefficient.

However, because the race-free equations may yield slightly different eGFR values compared to older equations, trends in eGFR should be assessed using results from a single equation. During the transition to the race-free equations, understanding how results from the older race-based equations compare to results using the race-free equations will allow patients and clinicians to better understand changes in eGFR over time, independent of changes caused by a transition in estimating equations.

It may be useful to reference information on the following race-based equations, for use in individuals ages 18 and older, when assessing eGFR results calculated prior to the transition to the race-free equations.

Equations

NIDDK calculates eGFR using creatinine determinations that are traceable to an isotope dilution mass spectrometry (IDMS) reference measurement procedure and cystatin C determinations that are traceable to ERM-DA471_IFCC HUMAN SERUM (cystatin C) certified reference material.

2009 CKD-EPI Creatinine Equation

The 2009 CKD-EPI creatinine equation was the most commonly used eGFR equation in the United States at the time the race-free 2021 CKD-EPI equations were developed. The equation uses a 2-slope “spline” to model the relationship between GFR and age, sex, race, and serum creatinine.1 The equation can be calculated in conventional or SI units.

Conventional Units

The equation can be expressed as a single equation in conventional units:

eGFR = 141 × min(SCr/κ, 1)α × max(SCr/κ, 1)-1.209 × 0.993Age × 1.018 [if female] × 1.159 [if African American]

Abbreviations/units

  • eGFR = estimated GFR in mL/min/1.73 m2
  • SCr = standardized serum creatinine in mg/dL
  • κ = 0.7 (females) or 0.9 (males)
  • α = -0.329 (females) or -0.411 (males)
  • min = indicates the minimum of SCr/κ or 1
  • max = indicates the maximum of SCr/κ or 1
  • age = years

Alternately, the equation can be expressed as a series of equations for different race, sex, and creatinine conditions, as shown in Table 1.

Table 1. 2009 CKD-EPI creatinine equation for estimating GFR expressed for specified race, sex, and serum creatinine in mg/dL (conventional units)

Race Sex Serum creatinine, SCr (mg/dL) Equation (age in years for ≥ 18)
Black female ≤ 0.7 GFR = 166 × (SCr/0.7)-0.329 × (0.993)Age
Black female > 0.7 GFR = 166 × (SCr/0.7)-1.209 × (0.993)Age
Black male ≤ 0.9 GFR = 163 × (SCr/0.9)-0.411 × (0.993)Age
Black male > 0.9 GFR = 163 × (SCr/0.9)-1.209 × (0.993)Age
White or other female ≤ 0.7 GFR = 144 × (SCr/0.7)-0.329 × (0.993)Age
White or other female > 0.7 GFR = 144 × (SCr/0.7)-1.209 × (0.993)Age
White or other male ≤ 0.9 GFR = 141 × (SCr/0.9)-0.411 × (0.993)Age
White or other male > 0.9 GFR = 141 × (SCr/0.9)-1.209 × (0.993)Age

SI Units

The equation can be expressed as a single equation in SI units:

eGFR = 141 × min(SCr/κ, 1)α × max(SCr/κ, 1)-1.209 × 0.993Age × 1.018 [if female] × 1.159 [if African American]

Abbreviations/units

  • eGFR = estimated GFR in mL/min/1.73 m2
  • SCr = standardized serum creatinine in µmol/L
  • κ = 61.9 (females) or 79.6 (males)
  • α = -0.329 (females) or -0.411 (males)
  • min = indicates the minimum of SCr/κ or 1
  • max = indicates the maximum of SCr/κ or 1
  • age = years

Alternately, the equation can be expressed as a series of equations for different race, sex, and creatinine conditions, as shown in Table 2.

Table 2. 2009 CKD-EPI creatinine equation for estimating GFR expressed for specified race, sex, and serum creatinine in µmol/L (SI units)

Race Sex Serum Creatinine, SCr (µmol/L) Equation (age in years for ≥ 18)
Black female ≤ 61.9 GFR = 166 × (SCr/61.9)-0.329 × (0.993)Age
Black female > 61.9 GFR = 166 × (SCr/61.9)-1.209 × (0.993)Age
Black male ≤ 79.6 GFR = 163 × (SCr/79.6)-0.411 × (0.993)Age
Black male > 79.6 GFR = 163 × (SCr/79.6)-1.209 × (0.993)Age
White or other female ≤ 61.9 GFR = 144 × (SCr/61.9)-0.329 × (0.993)Age
White or other female > 61.9 GFR = 144 × (SCr/61.9)-1.209 × (0.993)Age
White or other male ≤ 79.6 GFR = 141 × (SCr/79.6)-0.411 × (0.993)Age
White or other male > 79.6 GFR = 141 × (SCr/79.6)-1.209 × (0.993)Age

MDRD Study Equation

The MDRD Study equation estimates GFR using age, sex, race, and serum creatinine.2 The equation can be calculated in conventional or SI units.

Conventional Units

eGFR = 175 × (SCr)–1.154 × (Age)–0.203 × (0.742 if female) × (1.212 if African American)

Abbreviations/units

  • eGFR = estimated GFR in mL/min/1.73 m2
  • SCr = standardized serum creatinine in mg/dL
  • age = years

SI Units

eGFR = 175 × (SCr/88.4)–1.154 × (Age)–0.203 × (0.742 if female) × (1.212 if African American)

Abbreviations/units

  • eGFR = estimated GFR in mL/min/1.73 m2
  • SCr = standardized serum creatinine in µmol/L
  • age = years

References

Last Reviewed May 2024