Martin
I always like the way that these equations 'correct' for body surface area.
The rationale for always adjusting GFR to body surface area apparently dates
back to the 19th century when the ‘law of surface area’ was used in
physiology and medicine to calculate fluid and drug requirements. In the
mid 20th century, the application of BSA formulae to urea clearance seemed
to give children and adults comparable numerical values, and since then the
utilisation of this adjustment has fallen, largely unquestioned, into common
use.
Added to this is the fact that true GFR can increase by up to 70% due to
physiological changes such as a high protein load. Taken together, it does
make you wonder how good the 'gold standard' measurements are in these
studies which pinpoint GFR at a particular instant and then 'corrects' for
BSA.
Eric
>From: "Myers Martin (Dr)" <[log in to unmask]>
>Reply-To: "Myers Martin (Dr)" <[log in to unmask]>
>To: [log in to unmask]
>Subject: calculated GFR
>Date: Tue, 19 Oct 2004 11:38:46 +0100
>
>Is anyone confident enough to use the Modified MDRD calculation (or one the
>many others) as part of an adult electrolyte profile (Na, K, urea,
>creatinine) to give a better indication of GFR?
>
>The proposed use of the NKF K/DOQI classification of stages of chronic
>kidney disease, using calculated GFR, seems to gaining momentum.
>
>A case being put forward locally is: as creatinine is no good for detecting
>early kidney failure, and the "evidence" shows that calculated GFR is as
>good as creatinine clearance, and physicians would rather GFR than serum
>creatinine, then why not report calculated GFR with all its associated
>errors?
>
>regards
>
>Martin Myers
>
>
>
><http://www.kidney.org/professionals/doqi/kdoqi/p5_lab_g4.htm>
>
><http://bmj.bmjjournals.com/cgi/reprint/325/7355/85>
>
>http://bmj.bmjjournals.com/cgi/reprint/329/7471/912
>
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