Glomerular Filtration Rate (GFR) is the best overall measure of renal function. The most
accurate measurement of GFR requires complex technology which is not routinely available.
Alternate estimates of the GFR (eGFR) can be made by the following methods:
Estimate of GFR (eGFR) by MDRD formula (which
requires age, sex and serum creatinine only). The MDRD formula for estimation of
GFR is recommended for routine use and is reported with all requests for
serum creatinine. See below for further information.
Estimate of GFR by the Cockcroft and Gault
equation (which requires patient age, sex, weight or height, and serum
creatinine). This estimate is recommended for drug dosing decisions (on-line calculator).
Measurement of Creatinine Clearance
(which requires a serum creatinine measurement and a 24 hour urine collection). This is
the least reliable method for routine use but is valuable in extremes of body composition
where the estimation formulae above are not reliable.
eGFR using MDRD Formula
(on line calculator)
eGFR (mL/min/1.73m2)= 175 x [SerumCreatinine(umol/L) x 0.0113]-1.154
x Age(years)-0.203 (x 0.742 if female)
Note: This version of the MDRD formula (with 175 in plce of 186 as the
first coefficient), is sutiable for use with creatinine assays aligned with the
international reference method.
eGFR by MDRD: NOTES
- eGFR using the MDRD equation will be reported with all requests for serum creatinine.
- This is a recommendation of the peak renal and pathology bodies in Australia (Chronic
Kidney Disease and Automatic reporting of glomerular filtration rate: a position
statement. MJA 2005;183 (3): 138-141. www.mja.com.au)
- The formula is named after the Modification of Diet in Renal Disease study in the USA.
- The results are expressed relative to a standard body surface area of 1.73 m2
to allow for different body sizes. The units are mL/min/1.73m2.
- The equation is only valid in persons 18 years of age or older and not reported in
- Results >60 mL/min/1.73m2 are likely to deviate from the true value and
are not routinely reported.
- The use of the eGFR in patients on dialysis is inappropriate and will give misleading
- The formula has not been validated for drug dosing and alternate estimates of GFR such
as the Cockcroft and Gault methods should be used.
- The formula has not been validated in Aboriginals, Pacific Islanders or Chinese people
and results may deviate from the true value. For African-American patients multiply result
- Results may deviate from true values in patients with exceptional dietary intake (eg
vegetarian diet, high protein diet, creatine supplements); extremes of body composition
(eg lean, obese, paraplegia), or severe liver disease.
- Drug Dosing information in Australia (eg MIMS, Australian Medicines Handbook,
Therapeutic Guidelines) is based on Cockcroft and Gault estimates of creatinine clearance.
Cockcroft and Gault is recommended for drug dosing decisions.
eGFR by MDRD: INTERPRETATION
The MDRD estimate of GFR can be used for identification of moderate to severe decrease
in renal function and as a staging tool for Chronic Kidney Disease (CKD)
- eGFR >59 mL/min/1.73m2 - Normal GFR or mild decrease in GFR
- eGFR 30 - 59 mL/min/1.73m2 - Moderate decrease in GFR (Stage 3
- eGFR 15 - 29 mL/min/1.73m2 - Severe decrease in GFR (Stage 4 CKD)
- eGFR <16 mL/min/1.73m2 - End-stage kidney failure (Stage 5 CKD)
- The MDRD eGFR is NOT a sensitive test for renal failure and cannot be used to detect
mild renal impairment (GFR 60 - 90 mL/min/1.73m2).
- Results >60 mL/min/1.73m2 do not necessarily indicate normal renal
- The most sensitive routine test for small reductions in GFR is a comparison of a serum
creatinine concentration with a previous result from the same patient. An increase of 15%
or more in serum creatinine indicates a significant fall in GFR.
For futher information and clinical action plans see the Kidney Health
Australia website (www.kidney.org.au/calculator)