Volume 184 - Issue 9
Chronic kidney disease and automatic reporting of estimated glomerular filtration rate
Author: Alan McNeil
Med J Aust 2006; 184 (9): 476-477. || doi: 10.5694/j.1326-5377.2006.tb00329.x
Published online: 1 May 2006
Published online: 1 May 2006
To the Editor: I agree with Jones1 that the body surface area (BSA) formula printed in the position statement on reporting of estimated glomerular filtration rate (eGFR)2 is wrong, even though the authors say that he is mistaken.3
As stated by Jones, the correct formula4 for BSA in m2, for a body weight W kg and height H cm is:
However, the position statement2 gave the following formulas:
(ii) BSA = W0.425 × H0.725 × 0.007184/1.73; and
(iii) Uncorrected eGFR = GFR estimate (mL/min/1.73m2) × BSA.
It appears that the denominator “1.73” has migrated from formula (iii) to formula (ii), so in fact both of these formulas are incorrect. This is potentially misleading for doctors and others who may want to calculate the eGFR for someone who is unusually big or small.
Formula (iii) should in fact be:
It is interesting that the same two errors in BSA calculations are present on the US National Kidney Disease Education Program website,5 which was presumably the source of the formulas used by the Australian Creatinine Consensus Working Group.
References
- Jones TE. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate [letter]. Med J Aust 2006; 184: 42. 0_CBBHEFDF
- Australian Creatinine Consensus Working Group. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: a position statement. Med J Aust 2005; 183: 138-141. 0_CBBDABFG
- Mathew TH, Jones G, Johnson D, on behalf of the Australasian Creatinine Consensus Working Group. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate [letter]. Med J Aust 2006; 184: 43. 0_CBBCFJDA
- Halls e MD. Body surface area calculator. Available at: http://www.halls.md/body-surface-area/refs.htm (accessed Jan 2006).
- US National Kidney Disease Education Program. Health professionals: frequently asked questions about estimated GFR values. Available at: http://www.nkdep.nih.gov/professionals/gfr_calculators/gfr_faq.htm (accessed Jan 2006).