Iron and total iron-binding capacity in serum of patients receiving iron-dextran: Kodak Ektachem methodologies, spectrophotometry, and atomic-absorption spectrometry compared.
We compared the analytical performance of the Kodak Ektachem XR700 assays of iron (Fe) and total iron-binding capacity (TIBC) with that of a conventional ferrozine assay (performed with a Cobas-Bio) and occasionally with that of atomic-absorption spectrometry (AAS). The correlation was modest between Kodak and Cobas-Bio concentrations of Fe in serum (r = 0.79). Multiple outliers were noticed in samples from hemodialysis patients, with Cobas values exceeding those of Kodak by as much as 26 mumol/L. These intermethod differences were not dissipated by dialysis, but were invariably accompanied by an even higher total Fe content of the serum as judged by AAS (20 to 80 mumol/L higher). TIBC values by Kodak and Cobas-Bio were highly correlated (r = 0.99); again, the Cobas-Bio results exceeded those by Kodak in some hemodialysis patients, but always for samples with higher Fe concentrations by the Cobas-Bio. By AAS, the TIBC values of these patients also exceeded those by Kodak, to about the same extent as observed for serum Fe. These intermethod differences in Fe and TIBC were seen only in patients who had received an intravenous Fe-dextran (Imferon) injection two to three days before blood sampling but could be generated in vitro by adding Imferon to serum from normal controls. Less than 6% of dextran-bound Fe is measured as Fe by Kodak, as opposed to 20-30% by Cobas-Bio and 89-120% by AAS. We conclude that the Kodak Fe slides are superior to liquid reagents, by exclusively measuring protein-bound circulating Fe pools.
Department of Clinical Chemistry, Akademisch Ziekenhuis, Vrije Universiteit Brussel, Belgium.
M
M
Vercammen
W
W
Goedhuys
A
A
Boeyckens
R
R
De Roy
J
J
Sennesael
C
C
Sevens
F
F
Gorus
D001322:Autoanalysis / Q000295:instrumentation; D006801:Humans; D007275:Injections, Intravenous; D007501:Iron / Q000097:blood*; D007505:Iron-Dextran Complex / Q000008:administration & dosage* / Q000097:blood; D011485:Protein Binding; D013053:Spectrophotometry; D013054:Spectrophotometry, Atomic
D007505:Iron-Dextran Complex; D007501:Iron