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I sort of agree, except that the reference range for corrected calcium shouldn't coincide with that of total calcium (expected to be somewhat narrower given that the dispersion of total calcium is at least to some degree related to differences in albumin). In practice it might be reasonable to quote the same range. The critical issue is to check the reference range for calculated corrected calcium using a group of subjects other than those on whom the formula was derived. We need to impress on clinicians that the correction is simply a rule of thumb. Whether we need more than a rule of thumb in most patients is questionable in my view. The rationale for measuring ionised calcium (by no means a perfect measurement) in everyone depends on the perceived utility of detecting subtle degrees hyper/hypocalcaemia. Aubrey Blumsohn > As I understand it, the idea of all these corrections is to indicate what > the (total) calcium would be were the albumin concentration to be normal: > thus the reference interval for total and corrected should coincide. All > the 'corrections' are approximations, and I believe that their validity > declines at very low albumin concentrations (when one might want most to > use them). In practice, surely the 'corrected' value just gives you an > idea of whether there may be a significant abnormality of calcium > homoeostasis in a patient with an abnormal calcium concentration whose > albumin is also abnormal? As always, minor degrees of variation from > 'normal' may not be of significance, just as a just 'normal' (near upper or > lower reference value) calcium (even corrected) does not exclude abnormal > calcium homoeostasis. > WJM > At 08:41 AM 5/11/01 0100, Myers, Martin wrote: > >Most text books have reference ranges for total calcium, but not corrected > >calcium. If both total calcium and corrected calcium is reported do labs > >give a reference range for both or just one. > > > >martin myers > > >