Surely another reason for doing 24 hour collections is to gain an integral
of the diurnal variations in urine creatinine. This assumed, one would have
to have various reference ranges compatible with 6 hour collections starting
at different hours of the day, and one would need separate ranges for
night-shift workers as well !
I seem to recall (prove me wrong) finding a paper (circa 1975) relating
creatinine clearance (24 hr) to cytotoxic dosage which was oft quoted as the
definitive text. On closer analysis it was based on n<10 patients. When
taken to task, I have found that almost all dosers will act on serum
creatinine and clinical acumen alone when calculating doses.
With best wishes
Richard
-----Original Message-----
From: TICKNER TREVOR (RM1) Norfolk and Norwich NHS Trust
[mailto:[log in to unmask]]
Sent: Wednesday, January 09, 2002 15:14
To: [log in to unmask]
Subject: Re: Creatinine clearance test using 6 hours timed urine
collectio n
The logic of using a creatinine clearance emulator intrigues me.
The purpose of measurement of clearance is to direct a clinical management
decision. If an algorithm based on serum/plasma creatinine plus other data
such as sex can be used to emulate clearance and that is then used to direct
the decision, is not one actually using a sex/racial/weight 'corrected'
function of serum/plasma creatinine to define the action limits?
Would it not, therefore, be more logical to seek direct rather than indirect
associations between serum/plasma creatinine concentration and outcome?
Trevor Tickner,
Norwich
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