I have no experience of Cystatin C at all, but is far as I can work out the
jury is still out about whether it is a substantially better predictor of 
GFR than serum creatinine even in kids (eg. see Clinical Chemistry. 
1998;44:1334-1338 which showed no better prediction). In adults?? 

Why does creatinine clearance cost £15?:  Urine bottle £0.50, urine 
creatinine £0.20, labour determining volume £0.30, bit of extra 
portering £0.11 = £1.11, serum Cr done anyway + add a whole stack of 
overhead similar for both.  

Aubrey Blumsohn


>As far as I am aware no one is using cystatin C routinely as yet but would
>be very interested to no if I am mistaken. The case for  cystatin C is not
>proven as yet, it has great potential but more work is still required with
>further adaptations of methods for use on mainline analysers. As there are
>many creatinine clearances still being performed with the waste of time and
>money they entail it will clearly take quite a while for cystatin C to be
>introduced in clinical practice. This is the best point of attack as far as
>I can see with creatinine clearance costing something like £15 and cystatin
>C probably nearer £8. Any thoughts?
>
>David Newman
>
>
>Consultant Scientist & Scientific Director
>SW Thames Institute for Renal Research
>Tel:  (181) 296 3698
>Fax: (181) 644 8257
>----------
>> From: Michael Dr <[log in to unmask]>
>> To: Brian Payne <[log in to unmask]>; acb-clin-chem-gen
><[log in to unmask]>
>> Subject: Re: creatinine clearance etc.
>> Date: 06 August 1999 17:45
>> 
>> Interesting debate re GFR. As a matter of interest, has anybody changed
>the
>> 'serum/urine creatinine method' for serum cystatin-C, or am I the only
>one
>> intersted in this ?
>> 
>> Michael Ryan
>> 
>> ----------
>> > From: Brian Payne <[log in to unmask]>
>> > To: acb-clin-chem-gen <[log in to unmask]>
>> > Subject: Re: creatinine clearance etc.
>> > Date: Tuesday, July 27, 1999 8:17 PM
>> > 
>> > Donald Barber asked whether, if you eat 6 steaks a day, you excrete in
>> > the urine any of the creatinine you ingest. Your urinary excretion of
>> > creatinine is increased after meat both by preformed creatinine and by
>> > the conversion of creatine to creatinine.  The plasma concentration of
>> > creatinine increases substantially after a meat meal, so how big an
>> > increase in creatinine clearance you get depends on how you time the
>> > blood and urine collections.  True GFR also increases transiently in
>> > response to food during the day. (For references to the above see
>review
>> > article 'Creatinine clearance: a redundant clinical investigation' in
>> > Ann Clin Biochem 1986; 23: 243.) I found no papers on anabolic steroids
>> > influencing creatinine clearance or on creatine interfering with
>> > creatinine measurement when I searched the literature for the article.
>> > 
>> > The question about the effect of the ingestion of creatine was answered
>> > many years ago. Urine creatinine was increased by dietary creatine
>after
>> > about two weeks, it was maintained while intake continued with a
>> > recovery of about 30%, and it took some weeks to return to normal after
>> > creatine intake was discontinued (J Biol Chem 1928; 77: 171).  
>> > 
>> > With best wishes
>> > 
>> > Brian Payne
>> > 
>> > Tel: (0)113 266 1577
>
>



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