1Department of Health Science and Technology, Laboratory of Human Nutrition, ETH Zürich, Schmelzbergstr. 7, 8092 Zürich, Switzerland, Phone: +41 44 632 43 15, Fax: +41 44 632 14 702Department of Health Science and Technology, Laboratory of Human Nutrition, ETH Zürich, Zürich, Switzerland3Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands4Hepcidinanalysis.com, Laboratory Medicine, Nijmegen, The Netherlands5Department of Health Science and Technology, Laboratory of Human Nutrition, ETH Zürich, Schmelzbergstr. 7, 8092 Zürich, Switzerland, Phone: +41 44 632 84 36, Fax: +41 44 632 14 70
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Background:Hepcidin is the central systemic regulator of iron metabolism, but its quantification in biological fluids is challenging. Rapid, accurate and user-friendly methods are needed. Our aim was to assess the ability of hepcidin as measured by three different c-ELISA assays to predict iron bioavailability in humans.Methods:The three assays used were commercially available DRG and Peninsula assays and the c-ELISA method performed at Radboud University Medical Centre, Nijmegen, The Netherlands (Hepcidinanalysis.com), validated by comparative measurements with time-of-flight mass spectrometry. We analyzed plasma samples (n=37) selected to represent a broad range of hepcidin concentrations from a subgroup of healthy, iron-depleted women in a study assessing fractional absorption from iron supplements.Results:In single regressions, all three c-ELISA assays were predictors of fractional iron absorption: R2=0.363 (DRG), R2=0.281 (Peninsula) and R2=0.327 (Hepcidinanalysis.com). In multiple regressions, models including hepcidin measured with either DRG-, Peninsula or Hepcidinanalysis.com explained 55.7%, 44.5% and 52.5% of variance in fractional absorption, and hepcidin was a strong predictor of fractional absorption irrespective of the hepcidin assays used. However, we found significant differences in absolute values for hepcidin between different methods. Both the DRG assay's (y=0.61x+0.87; R2=0.873) and the Peninsula assay's measurements (y=1.88x+0.62; R2=0.770) were correlated with Hepcidinanalysis.com.Conclusions:The biological variability in plasma hepcidin, (inter-sample CV) was 5-10-fold higher for both the Peninsula and DRG assay than the analytical variably (inter-run within-sample CV) suggesting substantial discriminatory power to distinguish biological hepcidin variation. Between methods, prediction of iron bioavailability in generally healthy iron depleted subjects appears comparable.