Dear Peadar and colleagues,
The issue of the MW of transferrin was considered by John Beilby from Western Australia (Clin Chem 1992;38:2078) who recommend the adoption of a standard MW for transferrin of 79570 based on Macgillivray RTA (J Biol Chem 1983;258:3543-53).
A recent survey of equations for transferrin in Australia through the RCPAQAP identified at least 8 versions of a transferring saturation equation, all different because of (sometimes slight) differences in the selectoin of MW for transferrin.
I would support John Beilby's recommendation (and we will be discussing this for consideration of a common equation in Australia very shortly).
Regards,
Graham
Graham Jones
Chemical Pathologist
St Vincent's Hospital, Sydney
________________________________________
From: Clinical biochemistry discussion list <[log in to unmask]> on behalf of Dr Peadar McGing <[log in to unmask]>
Sent: Tuesday, 15 April 2014 9:05 PM
To: [log in to unmask]
Subject: transferrin saturation calculation from direct transferrin measurement
Dear colleagues,
Apologies for raising this topic which has featured on the mailbase a few times over the past few years. The problem is I can't see any clear picture emerging and wonder if I can get some help.
I am concerned about the 'correct' formula to use in calculating 'Iron Saturation' / 'Transferrin Saturation' when measuring transferrin directly.
I would appreciate feedback from anyone whose lab uses transferrin measurement to calculate iron saturation. Could you please let me know what formula you use and what origin / literature reference you quote in support.
The main formula I see is
% saturation = [iron (mmol/L) / transferrin (g/L)] x 3.98.
This seems to be based on mol wt of transferrin of 79,570 or 79,680, both of which I have original references for, giving TIBC = transferrin x 25.1 (from which we calculate 100/25.1 = 3.98 when converting TIBC formula).
A second equation I have seen quoted is
% saturation = [iron (mmol/L) / transferrin (g/L)] x 3.83.
This seems to be based on mol wt of transferrin of about 76,600 giving TIBC = transferrin x 26.1 (from which we calculate 100/26.1 = 3.83 when converting TIBC formula). I haven't manage to get any original reference for this.
Thanks in anticipation. I will provide feedback to the mailbase.
best wishes.
Peadar
Dr Peadar McGing, FRCPath EurClinChem,
Principal Biochemist,
Department of Clinical Chemistry and Diagnostic Endocrinology,
Mater Misericordiae University Hospital,
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