# Multi-ethnic eGFR Calculator

*Krzysztof Kiryluk, MD, MS and David A. Fasel*

This calculator is used to estimate glomerular filtration rate (eGFR) using recent formulas for adults of various ethnic backgrounds. For individuals 21 and under, the Schwartz pediatric equation is also included. The GFR estimation is valid only under the assumption of steady state renal function.

**Select the appropriate age group and enter values to estimate GFR in ml/min/1.73 m ^{2}: **

**Interpreting eGFR values:**

The various equations for estimating GFR can give a wide range of values, and although no equation is perfect, here are some generalizations about the accuracy of the formulas.

In patients with normal or near-normal kidney function, the MDRD and Cockcroft-Gault
equations may underestimate GFR. For these individuals, the CKD-EPI equations may be more accurate.^{1 } The
MDRD equation for Chinese may overestimate GFR values, and this value should be taken into consideration
with the estimated GFR of the Japanese equation given similarities in genetics, diet and lifestyle.
Differences between the way that serum creatinine was measured in China, versus Japan and the United
States may account for this discrepency.^{2}

The Cockcroft-Gault equation estimates creatinine clearance and is not adjusted
for body surface area.^{1,3} In contrast, the CKD-EPI and MDRD equations estimate
GFR adjusted for body surface area. Although the estimates based on the Cockcroft-Gault equation
continue to be used for drug dosage recommendations, this equation is considerably less accurate
with the standardized creatinine values,^{4} and specifically in older and more obese
individuals. Because of the inclusion of weight (as a measure of muscle mass) in the numerator, the
Cockcroft-Gault equation overestimates creatinine clearance in patients who are edematous or have
high body fat content.^{5}

** CDK Stages:**

Stage | GFR | Description |
---|---|---|

1 | 90+ | Normal kidney function |

2 | 60-89 | Mildly reduced kidney function |

3 | 30-59 | Moderately reduced kidney function |

4 | 15-29 | Severely reduced kidney function |

5 | < 15 | Very severe, or endstage kidney failure |

The value of estimated GFR defines a stage of chronic kidney disease (CKD), as recommended by the KDOQI initiative. The CKD staging should only be performed for individuals in steady state kidney function. These estimates are not valid for individuals in acute renal failure.

All individuals with a GFR <60 mL/min/1.73 m^{2} for more than 3 months are classified as having CKD. The reduction in kidney function to this level or lower represents loss of half or more of the adult level of normal kidney function.

**GFR Estimation Equations:**

**CKD EPI equation ^{1}:**

eGFR = 141 × min(Scr/k,1)

^{a}× max(Scr/k,1)

^{-1.209}× 0.993

^{Age}× (1.018 if female) × (1.159 if black).

Where Scr is serum creatinine (mg/dL), k is 0.7 for females and 0.9 for males, a is –0.329 for females and –0.411 for males, min indicates the minimum of Scr/k or 1, and max indicates the maximum of Scr/k or 1

**Cockcroft - Gault ^{3}:**

Estimated Creatinine Clearance (eC

_{Cr}) = [(140 - Age) × (Mass in kg) × (0.85 if Female)] / (72 × Serum Creatinine)

**MDRD equation ^{6}: **

eGFR = 175 × (Serum Creatinine)

^{-1.154}× (Age)

^{-0.203}× (0.742 if Female) × (1.212 if Black)

**C-MDRD (modified for Chinese) equation ^{7}: **

eGFR = 175 × (Serum Creatinine)

^{-1.234}× (Age)

^{-0.179}× (0.79 if Female)

**J-MDRD (modified for Japanese) equation ^{8}: **

eGFR = 194 × (Serum Creatinine)

^{-1.094}× (Age)

^{-0.287}x (0.739 if Female)

**Schwartz equation ^{9}: **

eGFR = (

*d*× Height)/(Serum Creatinine)

Variable

*d*is the proportionality constant given by the age group of the child, where

*d*= 0.33 for low birth weight infants;

*d*= 0.45 for full term infants;

*d*= 0.55 for children ages 2-12 and girls 13-21; and

*d*= 0.70 for boys 13-21 years old.

**References:**

- Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF 3rd, Feldman HI, Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J; CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration). A New Equation to Estimate Glomerular Filtration Rate. Ann Intern Med 2009; 150(9):604-12.
- Dai SS, Yasuda Y, Zhang CL, Horio M, Zuo L, Wang HY. Evaluation of GFR measurement method as an explanation for differences among GFR estimation equations. Am J Kidney Dis. 2011 Sep; 58(3):496-8.
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976; 16(1):31-41.
- Stevens LA, Manzi J, Levey AS, et al. Impact of creatinine calibration on performance of GFR estimating equations in a pooled individual patient database. Am J Kidney Dis.2007;50(1):21-35.
- Coresh J, Stevens LA. Kidney function estimating equations: where do we stand? Curr Opin Nephrol Hypertens. 2006;15(3):276-284.
- Levey AS, Coresh J, Greene T, Stevens LA, Zhang YL, Hendriksen S, Kusek JW, Van Lente F; Chronic Kidney Disease Epidemiology Collaboration. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med. 2006 Aug 15;145(4):247-54.
- Ma Y, Zuo L, Chen J
*et al.*Modified glomerular filtration rate estimating equation for Chinese patients with chronic kidney disease. J Am Soc Nephrol 2006: 17: 2937. - Matsuo S, Imai E, Horio M, Yasuda Y, Tomita K, Nitta K, Yamagata K, Tomino Y, Yokoyama H, Hishida A. Revised equations for estimated GFR from serum creatinine in Japan. Am J Kidney Dis.2009;53:982–992.
- Schwartz GJ, Brion LP, Spitzer A. The use of plasma creatinine concentration for estimating glomerular filtration rate in infants, children, and adolescents. Pediatric Clinics of North America 1987; 34:571-590.

**Disclaimer:**

All calculations must be confirmed before use. The authors make no claims of the accuracy of the information contained herein. The information provided here does not imply medical advice.

*Last updated 8/2012*