Melbourne Health Shared Pathology Service
estimated Glomerular filtration rate (eGFR)
5 ml blood, lithium-heparin or serum tube for the assay of creatinine.
Specimen
The eGFR is derived from the assay of creatinine in plasma or serum using the
abbreviated MDRD formula as recommended for use in Australia.
The LIS accesses the patient’s age and gender to complete the calculation.
Test availability
Creatinine is assayed daily.
M&F, >18 years of age: > 90 ml/min/1.73m2 of body surface.
The abbreviated MDRD equation is
Reference
interval and
derivation
adult
eGFR = 175 * ([SCR/88.4]–1.154) * (age)–0.203 * (0.74 if female) * (1.2 if “African-American”)
SCR = serum creatinine concentration (μmol/L); age is expressed in years.
The result is “normalized” to a body surface area [BSA] of 1.73m 2.

Only patients with extreme variations from ideal body mass index [BMI] values require
correction from the normalized BSA value.

This is done by multiplying the reported value by the specific patient’s BSA (m2 , derived
using the formula of the Des Bois), and dividing by 1.73.

BSA = W0.425 * H0.725 * 0.0072 [W = weight (kg), H = height (cm)]
The initial results were derived from a north American population and have not been verified for use
with other populations. Caution is suggested in using the eGFR with indigenous Australians and with
patients with Asian ancestry. Care must also be exercised in interpreting the term “AfricanAmerican”, the significance and meaning of which in Australia is not clear: the MH laboratories
instead use the phrase “of sub-Saharan African ancestry”.
Clinical application and rationale
Assessment of kidney function by reference to a criterion standard method – renal clearance of 125Iiothalamate – in a reference population. (Levey AS, 1999).

This method avoids the uncertainties involved in collecting urine and takes into account a large part of the
variation in creatinine measurements attributable to variation in age, gender, and muscle mass.
Clinical interpretation
Australian and UK authorities both support the use of the USA “K/DOQI” derived guidelines for chronic kidney
disease evaluation and classification, although the Australasian Working Group sets the lower limit of the
reference interval at 60 ml/min/1.73m2.
The K/DOQI stages of chronic kidney disease are:
Stage
Description
GFR (ml/min/1.73m2)
1
Kidney damage with normal or increased GFR
> 90
2
Kidney damage with a mild decrease in GFR
60 - 89
3
Moderately decreased GFR
30 - 59
4
Severely decreased GFR
15 - 29
5
Kidney failure
< 15, or on dialysis
“Chronic kidney disease” is also defined as either “kidney damage” or “GFR <60 ml/min/1.73m 2 for >3 mo”.
GFR declines with age. Although it is not clear whether this process is physiological, pathological, or possibly
both, it has been shown that eGFR 50-59 ml/etc at >64 y, and 40-49 ml/etc at >84 y, do not impose an
increased risk of death by comparison with people with eGFR >60 ml/etc at the same age. (O’Hare AM, 2006).
Links to
guidelines
References
Australian
UK
USA
The Australasian Creatinine Consensus Working Group.
The Joint Specialty Committee on Renal Disease of the RCPL and the RA.
National Kidney Foundation: Kidney Disease Outcomes Quality Initiative.
Levey AS et al. A more accurate method to estimate GFR … Ann Intern Med 1999; 130: 461-70.
O’Hare AM et al. Mortality risk stratification in CKD … J Am Soc Nephrol 2006; 17: 846-53.
This page last reviewed and verified: 30 Oct 2009 by C Chiang.
CHBIS-01,06 (30/10/09)
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