I'd be interested to hear what reference ranges people quote for corrected
calcium. We quote 2.15-2.65 mmol/l (Roche 917 with BCG albumin and formula
as per Peter). We a fair number of slightly low results and ionised calcium
is almost invariably normal. I think the cut off for correction of 15g/L is
much to low but I'm not aware of any data which addresses this issue. Any
offers?
Dermot Neely
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Dr RDG Neely
Department of Clinical Biochemistry
North Durham Healthcare NHS Trust
Dryburn Hospital
Durham DH1 5TW
Tel. 0191 3332440 Fax. 0191 3332679
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-----Original Message-----
From: Sharpe, Peter Dr [mailto:[log in to unmask]]
Sent: 05 October 2000 04:14
To: [log in to unmask]
Subject: corrected calcium
We give corrected calciums on all samples except when albumin<15 g/l. This
has met with great enthusiasm by both GPs and hospital medics.
We use the following formula:
Corrected calcium (mmol/l) = total calcium + 0.02(40 - albumin)
i.e. the measured total calcium is corrected upwards by 0.1 mmol/l for every
5 g/l that the albumin is less than 40 g/l.
The main reason for giving corrected calciums was that there was a degree of
ignorance among GPs in particular regarding total calciums and its
correction using the serum albumin concentration. We also correct our
calciums downwards for albumins > 40 g/l although this may not be an
entirely accurate thing to do??
In cases of difficulty we are lucky in having a near patient testing
instrument in ICU which measures ionized calcium.
All the best
Peter Sharpe
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