I don't know about the accuracy of BCP albumin-adjusted 
calcium, but I do know that ionized calcium measured on 
commercial analyzers is not itself independent of albumin 
concentration. There are references to the evidence in the 
Discussion of Masters PW, Payne RB. Clin Chem 1993; 39: 
1082-5. The full text is available free online.

Brian Payne


On Fri, 16 Apr 2010 11:40:29 +0100
  Rachel Smith <[log in to unmask]> wrote:
> Lynn,
> 
> At Luton & Dunstable Hospital, where I used to work, 
>they only calculate a 'corrected' calcium when the 
>albumin was > 20 g/l.  I imagine some work was done to 
>show that this was a reasonable cut off level but I don't 
>know.
> 
> As far as I understand an ionised calcium is generally a 
>better option for looking at the 'functional' calcium 
>level, but it's use is limited because of the expense and 
>the requirement for very quick testing after sampling, 
>keeping sample cold etc.
> 
> Rachel Smith
> 
> Birmingham Women's Hospital.
> 
> ________________________________
>From: Clinical biochemistry discussion list 
>[[log in to unmask]] On Behalf Of Lee, Lynn 
>[[log in to unmask]]
> Sent: 16 April 2010 10:48 AM
> To: [log in to unmask]
> Subject: Albumin Adjusted Calcium.
> 
> Hello,
> 
> Could any of the list members tell me if they have an 
>Albumin lower limit restriction when calculating 
>Corrected Calcium, using the formula:
> 
> Ca(corrected, mmol/L) = Ca( measured, mmol/L) + {(40 – 
>(Albumin) x 0.02}
> 
> We use the BCP method for measuring albumin and an 
>Arsenazo-III dye for Calcium.
> 
> I would be interested in your comments as to how 
>accurate you consider this formula to be at Albumin 
>levels less than 25g/L and at what level an ionized 
>Calcium would be more appropriate.
> 
> Acting Chief Biomedical Scientist,
> Noble's Hospital,
> Biochemistry Laboratory,
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> Tel 01624 650661
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> 
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