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.
Ian Barlow
> -----Original Message-----
> From: Grimes, Helen [SMTP:[log in to unmask]]
> Sent: Tuesday, October 31, 2000 9:42 AM
> To: 'Stephen Davis'
> Cc: 'ACBUK'
> Subject: RE: Acid in Urine collection bottles
>
> My understanding is that urine for Calcium has to be collected into acid,
> otherwise the Calcium salts precipitate out and are not redissolved on
> later
> acidification. Can any one confirm as to whether this is correct or not?
>
> -----Original Message-----
> From: Stephen Davis
> [mailto:[log in to unmask]]
> Sent: Tuesday, October 24, 2000 9:43 AM
> To: 'Robin Marks'
> Cc: 'ACB Mailbase'
> Subject: RE: Acid in Urine collection bottles
>
> It is possible to avoid issuing urine collection bottles
> containing acid if
> the urine is acidified after collection. Ortho recommend
> for their Vitro
> analysers that 2.0mL 6M HCl is added for every 100mL urine
> collected and
> then well mixed. Alternatively add 400uL 6M HCl to a 20mL
> aliquot of urine
> taken from a well mixed collection. The Vitros analysers
> correct for this
> dilution of urine but for other methods it would be
> necessary to allow for
> this in your calculations.
>
> Steve Davis
> Principal Biochemist
> Department of Clinical Biochemistry
> Royal Glamorgan Hospital
> Ynysmaerdy
> PONTYCLUN
> CF72 8XR
> Tel: (0)1443 443357
> Fax: (0)1443 443355
>
>
> -----Original Message-----
> From: Robin Marks [SMTP:[log in to unmask]]
> Sent: Tuesday, October 24, 2000 9:01 AM
> To: [log in to unmask]
> Subject: Acid in Urine collection bottles
>
> Acid in Urine collection bottles:
> Hi,
> Does anyone use an alternative to concentrated HCl
> in the bottle for 24 hour urine calcium collection ?
>
> Robin Marks
> Halifax UK
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