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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