Table 1.
Equations used to estimate GFR
| Equation | Notes |
|---|---|
| Creatinine | |
| Cockcroft–Gault19 | Does not estimate GFR |
| CrCl =(140−age)× weight (kg)/72× SCr | |
| CrCl = creatinine clearance (mL/min) | |
| SCr = serum creatinine (mg/100 mL) | |
| CKD-EPI20 GFR =141× minimum (SCr/κ, 1)α × maximum (SCr/κ, 1)−1.209×0.993Age×1.018 (if female) or 1.159 (if black) |
Apply correction factor to GFR values for people of African or Afro-Caribbean descent |
| κ =0.7 (female) or 0.9 (male) α =−0.329 (female) or −0.411 (male) |
Less biased than MDRD at estimating GFR in those with a GFR >60 mL/min/1.73 m2 |
| minimum = minimum SCr/κ or 1 maximum = maximum SCr/κ or 1 |
Better than MDRD at estimating GFR in patients aged ≥75 years |
| SCr = serum creatinine (mg/dL) | Interpret with caution in patients with extremes of muscle mass |
| MDRD study equation18,20 | May overdiagnose chronic kidney disease |
| GFR (mL/min/1.73 m2)=175 × (SCr)–1.154× (Age)−0.203×0.742 (if female) ×1.212 (if African-American) | May not be accurate for all racial groups |
| SCr = serum creatinine (mg/dL) | |
| Cystatin C | |
| CKD-EPI18 | More accurate than eGFR of creatinine |
| 133× minimum (SCysC/0.8, 1)−0.499× maximum (SCysC/0.8, 1)−1.328×0.996Age (×0.932 if female) | For confirmatory testing in specific circumstances when eGFR based on serum creatinine is less accurate |
| minimum = minimum SCysC/0.8 or 1 | |
| maximum = maximum SCysC/0.8 or 1 | |
| SCysC = serum cystatin C (mg/L) | |
| Creatinine–cystatin C | |
| CKD-EPI18 135× minimum (SCr/κ, 1)α× maximum (SCr/κ, 1)−0.601× minimum (SCysC/0.8, 1)−0.375× maximum (SCysC/0.8, 1)−0.711×0.995Age ×0.969 (if female) or ×1.08 [if black] |
More accurate than equations using creatinine or cystatin C separately |
| κ =0.7 (female) or 0.9 (male) | |
| α =−0.248 (female) or −0.207 (male) | |
| minimum (SCr/κ, 1) = minimum SCr/κ or 1 | |
| maximum (SCr/κ, 1) = maximum SCr/κ or 1 | |
| minimum (SCysC/0.8, 1) = minimum SCysC/0.8 or 1 | |
| maximum (SCysC/0.8, 1) = maximum SCysC/0.8 or 1 | |
| SCr = serum creatinine (mg/dL) | |
| SCysC = serum cystatin C (mg/L) | |
Abbreviations: CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; CrCl, creatinine clearance; eGFR, estimated glomerular filtration rate; GFR, glomerular filtration rate; MDRD, Modification of Diet in Renal Disease; SCr, serum creatinine; SCysC, serum cystatin C.