Iron in serum

H. L. "Ultramicro Method for Determination of Iron In Serum with the Graphite Furnace". Clin. Chem. (1973), 19, 326-329. 

The iron-binding protein of serum transferrin was found in fraction IV-3,4 of human plasma when the plasma was fractionated by low temperature ethanol fractionation procedures (31, 116). By further subfractionations, serum transferrin could be concentrated in Cohn fraction IV-7 (30, 125, 126). Cohn (30) first reported the properties of the isolated protein, which he called the 3i metal-binding protein since the protein had been found to bind copper, and possibly zinc, as well as iron. Holm-berg and Laurell (66) proposed that the protein be called transferrin on the basis that the principal function of the protein was associated with the transport of iron in serum and that it was not the major copperbinding protein in human serum. 

Note. In emergencies, especially involving young children, die serum sample may be aspirated directly into die flame to give an indication of intoxication. A screening test for ferrous and ferric iron is given on p. 5. Commercial kits for the assay of iron in serum are available (see Reagent Appendix). 

Fassett, J.D. Powell, L.J. Moore, L.J., The Determination of Iron in Serum and Water by Resonance Ionization Isotope Dilution Mass Spectrometry, submitted for publication. 

E630 Jacobs, J.C. and Alexander, N.M. (1990). Colorimetry and constant-potential coulometry determinations of transferrin-bound iron, total iron-binding capacity, and total iron in serum containing iron-dextran, with use of sodium di-thionite and alumina columns. Clin. Chem. 36, 1803-1807. 

E685 Valcour, A.A., Krzymowski, G., Onoroski, M., Bowers, G.N. and McComb, R.B. (1990). Proposed reference method for iron in serum used to evaluate two automated iron methods. Clin. Chem. 36, 1789-1792. 

The relationship is not entirely linear because a small portion of iron in serum is bound to other proteins. Therefore the calculated TIBC values are sHghtiy higher than the amount of transferrin-bound iron. These small differences, however, are of no practical consequence. Immunoassays are available for assay of serum transferrin concentration. Results of the immunological measurement of transferrin concentration correlate with those of the TIBC assay. A slight advantage for the immunoassay of transferrin is that the required volume per specimen is much smaller. 

Biquinoline and 2,9-diinethyl-l,10-phenanthroline are very specific reagents for copper but lack sensitivity (B17) nevertheless the latter has been used successfully for the determination of copper in certain foodstuffs (J5). 4,7-Diphenyl-1,10-phenanthroline and bathocuproine are more sensitive the latter is specific for copper to such an extent that it can be used for the simultaneous determination of both copper and iron in serum (Zl). 

International Committee for Standardization in Haematology (1990) Recommended method for measurement of iron in serum. British Journal of Haematology 75 615-616. 

A proposed reference method for iron in serum that is a modification of the ICSH method was recently presented [51,52a]. The modifications include reduction with ascorbic acid and somewhat different concentrations of TCA and HCl. In addition, thiourea and ferrozine chromogenic chelators were used in the modified procedure. Thiourea reduces interference from copper [45b 52b,c]. Analysis was performed in a centrifugal analyzer. This procedure produced results that correlated very well with the Kodak dry-film procedure [48,49]. 

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