I agree that if you are investigating renal stone formers then it is
essential to acidify urine DURING the collection so as to ensure calcium
oxalate is maintained in solution.
I disagree that urine calcium is unhelpful - an estimate of calcium
excretion (either 24 hour or calcium/creat clearance) is essentail for
teasing out BFHH from primary hyperparathyroidism.
- Ian
> -----Original Message-----
> From: Stuart Robertson [SMTP:[log in to unmask]]
> Sent: Tuesday, October 31, 2000 12:25 PM
> To: Ian Barlow
> Cc: [log in to unmask]
> Subject: RE: Acid in Urine collection bottles
>
>
>
> --- Ian Barlow <[log in to unmask]>
> wrote: > Calcium phosphate will re-dissolve readily
> after
> > acidification. However
> > calcium oxalate is very difficult to re-dissolve -
> > it requires urine pH to
> > be well below 2 and the sample should then be boiled
> > for about 30 mins for
> > maximum recovery. But please note that calcium
> > oxalate is very much the
> > minor constituent (< 0.5 mmol/L) in comparison to
> > calcium phosphate
> > therefore even if it was not fully recovered, post
> > acidification, the
> > effects on the result for 24 hour calcium excretion
> > would be relatively
> > small.
> >
>
> Is it not the case that 24 hour urine calcium is of
> limited use anyway, because it is so dependant on diet
> (amongst other things)?
> Urinary oxalate, on the other hand, is useful in
> investigation of stone formers, so it is important to
> ensure complete dissolution before analysis.
>
> Stuart Robertson
> Hull Royal Infirmary
> Hull
> HU3 2JZ
>
>
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