CKD-EPI Equations for Glomerular Filtration Rate (GFR)

CKD-EPI 2021 Calculator

Sex

Serum Creatinine

mg/dL

Age

years

Score:–

–

Estimates GFR in CKD patients using serum creatinine, cystatin C, or both .

Why Use

The CKD-EPI equation performs superiorly to the MDRD Equation in patients with normal or mildly reduced estimated GFR (eGFR), and just as well in patients with an eGFR of <60 mL/min/m 2 . It is used most widely by nephrologists and understood to be the most accurate means of non-invasively assessing GFR in the United States.

When to Use

Patients with chronic kidney disease (not acute), to measure kidney function. CKD-EPI Creatinine is more commonly available. 2021 CKD-EPI creatinine-cystatin is recommended as a confirmatory test in patients at extremes of body type (e.g. obese patients, high or low muscle mass).

Formula

2021 CKD-EPI Creatinine = 142 × (Scr/ A ) B × 0.9938 age × (1.012 if female), where A and B are the following: Female Male Scr ≤0.7 A = 0.7 B = -0.241 Scr ≤0.9 A = 0.9 B = -0.302 Scr >0.7 A = 0.7 B = -1.2 Scr >0.9 A = 0.9 B = -1.2 2021 CKD-EPI Creatinine-Cystatin C = 135 × (Scr/ A ) B × (Scys/ C ) D × 0.9961 age × (0.963 if female), where A , B , C , and D are the following: Female: Scr ≤0.7 Scr >0.7 Scys ≤0.8 A = 0.7 B = -0.219 C = 0.8 D = -0.323 A = 0.7 B = -0.544 C = 0.8 D = -0.323 Scys >0.8 A = 0.7 B = -0.219 C = 0.8 D = -0.778 A = 0.7 B = -0.544 C = 0.8 D = -0.778 Male: Scr ≤0.9 Scr >0.9 Scys ≤0.8 A = 0.9 B = -0.144 C = 0.8 D = -0.323 A = 0.9 B = -0.544 C = 0.8 D = -0.323 Scys >0.8 A = 0.9 B = -0.144 C = 0.8 D = -0.778 A = 0.9 B = -0.544 C = 0.8 D = -0.778 2009 CKD-EPI Creatinine = A × (Scr/ B ) C × 0.993 age × (1.159 if black*), where A, B , and C are the following: Female Male Scr ≤0.7 A = 144 B = 0.7 C = -0.329 Scr ≤0.9 A = 141 B = 0.9 C = -0.411 Scr >0.7 A = 144 B = 0.7 C = -1.209 Scr >0.9 A = 141 B = 0.9 C = -1.209 2012 CKD-EPI Cystatin C = 133 × (Scys/0.8) A × 0.996 age × B, where A and B are the following: Female Male Scys ≤0.8 A = -0.499 B = 0.932 A = -0.499 B = 1 Scys >0.8 A = -1.328 B = 0.932 A = -1.328 B = 1 2012 CKD-EPI Creatinine-Cystatin C = A × (Scr/ B) C × (Scys/0.8) D × 0.995 age × (1.08 if black*), where A, B, C, and D are the following: Female: Scr ≤0.7 Scr >0.7 Scys ≤0.8 A = 130 B = 0.7 C = -0.248 D = -0.375 A = 130 B = 0.7 C = -0.601 D = -0.375 Scys >0.8 A = 130 B = 0.7 C = -0.248 D = -0.711 A = 130 B = 0.7 C = -0.601 D = -0.711 Male: Scr ≤0.9 Scr >0.9 Scys ≤0.8 A = 135 B = 0.9 C = -0.207 D = -0.375 A = 135 B = 0.9 C = -0.601 D = -0.375 Scys >0.8 A = 135 B = 0.9 C = -0.207 D = -0.711 A = 135 B = 0.9 C = -0.601 D = -0.711 Scr, serum creatinine, mg/dL. Scys, serum cystatin C, mg/L. *Race may/may not provide better estimates of GFR; optional. See here for more on our approach to addressing race and bias on MDCalc.

Pearls / Pitfalls

In 2021 new equations were created to remove the race components from the prior CKD-Epi equations and should be the new standard equations; we continue to offer the prior equations for comparison/trending. Creatinine-based estimates of kidney function by glomerular filtration rate (GFR) are less accurate in certain populations including patients with diabetes (before progression to overt nephropathy with diminished GFR), pregnant women, those with unusual body mass (e.g. obese, severely malnourished, amputees, paraplegics, etc). Not for use in patients on dialysis.

Management

Patients should be classified into CKD stage by both eGFR and albuminuria status. Patients with decreased GFR, increased urinary albumin excretion or both, are at high risk of progressive CKD and should be referred to nephrology for further management. From KDIGO 2012 Clinical Practice Guideline .

Advice

Patients with decreased GFR are at higher risk of progressive kidney disease. Management of contributing risk factors, such as diabetes and hypertension, is critical to slowing progression. Investigation of the underlying cause of decreased GFR is warranted if not clear from the history. Medications should be dose-adjusted for the most recent available eGFR (in this setting, eGFR and creatinine clearance may be used interchangeably, though they are physiologically different terms). Cutoffs for many medications are <60, <45, and <30 mL/min/m 2 , as well as adjustments for advanced kidney disease and dialysis patients.

More Information

From KDIGO 2012 Clinical Practice Guideline .