We are soon to move from Roche UIBC / TIBC to Roche immunoturbidimetry direct transferrin. The haematinics profile will include Ferritin, Iron, Transferrin and TSAT (%SAT).
A short method verification (ACB protocol) found direct Transferrin levels 10-15% higher than an indirect estimate from the T/UIBC. Can list members confirm this finding and is it considered clinically significant?
Secondly, Transferrin saturation is traditionally calculated as (Iron/Iron+UIBC) x100. In this calculation, a saturation of >100% is technically not possible, except where a negative UIBC value occurs. When moving to direct Transferrin measurement, we plan to use a recognised formula, based on the known properties of transferrin iron binding to calculate TSAT (%SAT) - Iron (umol/L) x 4/Transferrin (g/L).
We anticipate in, for example iron overload or ESRD patients (with low Transferrin levels) receiving iron, to enounter more samples where the %SAT is GREATER than 100% - in some cases significantly so. How do list members report such results? Are they qualified in any way? Do clinicians consider such results as an indication of "free iron"? Can such an impression be relied upon clinically? What is your experience of change management from T/UIBC to direct Transferrin?
Thanks in anticipation
David Wright
Technical Lead BMS
Antrim Laboratory
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