We use the Cockroft estimation of the creatinine clearance since a couple of
years especially for outpatients as it is not necessary to collect 24 h
urine.
We don't use tables in a spreadsheet but a formula in our LIS. The patients
demographic is of course know in our system (age & sex), the patients weight
is entered in the LIS from the admission form and creatinine is measured. Th
clearance is calculated form the formula:
(1.2278 * kg * (140 - age))/ [serum creatinine in umol/L!] for males
and
(1.0436 * kg * (140 - age))/ [serum creatinine in umol/L!] for females
This is reported together with the measured/ entered values.
Of course we also perform the regular creatinine cleareance
Dr Dirk Bakkeren
clinical chemist
Diaconessenhuis Eindhoven
----- Oorspronkelijk bericht -----
Van: Dr J. Falconer Smith <[log in to unmask]>
Aan: <[log in to unmask]>
Verzonden: donderdag 12 augustus 1999 9:39
Onderwerp: virtual creatinine clearance
>
> Following discussion with on our my oncology colleagues
> I investigated the possibility of deriving calculated
> creatinine clearance values from serum creatinine alone.
> The medical algorithm site (links from the ACB www links page)
> provided a wealth of information.
>
> Taking advice from our renal physicians we chose
> the method of Cockcroft and Gault (although I also
> investigated the method of Siersbach-Nielsen which
> gives very similar results in men but somewhat different results in
women).
>
> Using the tables function within Excel it was possible
> to construct different tables for men and women showing
> the level of serum creatinine that corresponds to a
> creatinine clearance of 50 mls/min. (Cisplatin
> dosage is altered/witheld if clearance is <40 mls/min)
>
> All the clinicians need do is find an intersection between
> a patients age and weight (lean weight in obese subjects)
> and the corresponding cell gives the threshold serum creatinine
> value.
>
> Initial response of the oncologists is very positive and we are
> working together to characterise the limitations and use of
> this approach. We are well aware of possible imprecision but
> then creatinine clearance is not ideal in practice either.
>
> I thought this might be of interest to mailbase members.
> I will make the calculations and excel sheets available if
> there is any interest in them.
>
> James Falconer Smith
>
>
>
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