Comparison of four immunoassays to measure serum ferritin concentrations and iron deficiency prevalence among non-pregnant Cambodian women and Congolese children

Abstract

Background: Global standardization of ferritin assays is lacking, which could have direct implications on the accurate measurement and comparability of ferritin concentration and iron deficiency (ID) prevalence rates in at-risk populations. Methods: We measured serum ferritin concentrations using four immunoassays: the s-ELISA and the AxSYM™ analyzer were compared among 420 non-pregnant Cambodian women; the Centaur ® XP analyzer, s-ELISA, and AxSYM™ analyzer were compared among a subset of 100 Cambodian women; and the s-ELISA and the Elecsys

Comparison of a New Multiplex Immunoassay for Measurement of Ferritin, Soluble Transferrin Receptor, Retinol-Binding Protein, C-Reactive Protein and α1-Acid-glycoprotein Concentrations against a Widely-Used s-ELISA Method

“…Moreover, as can be seen in Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 in the results section, there is also a systematic shift for several biomarkers, in particular for ferritin, sTfR, and CRP, and to some extent RBP. Such bias may be a result of different affinity of the antibodies in the two methods [ 14 ] and as such, if proving to be constant, could be justifiably adjusted, in particular if absolute true values could be established to adjust for. However, this shift is not consistent across the samples from the three countries such that from this work, no factor-adjustment to render the two methods more comparable can be proposed without reservation.…”

“…Thus, it would be inappropriate to say that one method is wrong and the other is right, both may have shifts from the true concentrations of the analytes. Yet, the VitMin Lab method has undergone several critical assessments and mostly yielded good scores [ 2 , 14 ]; plus, it is so widely used that it is almost setting a benchmark for new methods to be compared against.…”

“…In our prior work, we measured serum ferritin concentrations using four different immunoassays, including Erhardt’s s-ELISA, in Cambodian women ( n = 420) and Congolese children ( n = 226) [ 14 ]. We observed differences in mean serum ferritin concentrations across assays, which were likely an inherent reflection of the different ferritin isoforms, antibodies, and calibrators used by these assays and labs [ 14 ]. Despite the differences in ferritin concentrations, iron deficiency prevalence was similar (and low) across the different ferritin methods [ 14 ].…”

“…We observed differences in mean serum ferritin concentrations across assays, which were likely an inherent reflection of the different ferritin isoforms, antibodies, and calibrators used by these assays and labs [ 14 ]. Despite the differences in ferritin concentrations, iron deficiency prevalence was similar (and low) across the different ferritin methods [ 14 ]. Similarly, we suspect that some of the observed differences in ferritin concentrations are likely due to the different analytical (isoforms and antibodies) and calibration techniques between the two methods.…”

A sandwich enzyme-linked immunosorbent assay for the quantitation of human plasma ferritin

“…Ferritin is a 24 subunit-protein comprised of two types of subunits (H and L) and the ratio of the different subunits varies with the ferritin isoform, for example ferritin from the heart contains mostly the H subunit but ferritin from the liver (and also ferritin in plasma) is primarily made up of the L subunit (reviewed in [7]). It has been suggested that variation in the isoform being measured is one possible explanation of variation between different assay systems for ferritin measurement [8] and therefore information regarding the source of ferritin towards which the antibodies used in assays were generated is important for comparing results measured using different methods.…”