Comparison of Two ELISA Methods and Mass Spectrometry for Measurement of Vitamin D-Binding Protein: Implications for the Assessment of Bioavailable Vitamin D Concentrations Across Genotypes Journal Article

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Authors: Denburg, M. R.; Hoofnagle, A. N.; Sayed, S.; Gupta, J.; de Boer, I. H.; Appel, L. J.; Durazo-Arvizu, R; Whitehead, K.; Feldman, H. I.; Leonard, M. B.; Chronic Renal Insufficiency Cohort study investigators
Article Title: Comparison of Two ELISA Methods and Mass Spectrometry for Measurement of Vitamin D-Binding Protein: Implications for the Assessment of Bioavailable Vitamin D Concentrations Across Genotypes
Abstract: Studies using vitamin D-binding protein (DBP) concentrations to estimate free and bioavailable vitamin D have increased dramatically in recent years. Combinations of two single-nucleotide polymorphisms (SNPs) produce three major DBP isoforms (Gc1f, Gc1s, and Gc2). A recent study showed that DBP concentrations quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) did not differ by race, whereas a widely used monoclonal enzyme-linked immunosorbent assay (ELISA) quantified DBP differentially by isoform, yielding significantly lower DBP concentrations in black versus white individuals. We compared measurements of serum DBP using a monoclonal ELISA, a polyclonal ELISA, and LC-MS/MS in 125 participants in the Chronic Renal Insufficiency Cohort (CRIC). Serum free and bioavailable 25OHD were calculated based on DBP concentrations from these three assays in homozygous participants, and race differences were compared. We confirmed that the monoclonal ELISA quantifies DBP differentially by isoform and showed that the polyclonal ELISA is not subject to this bias. Whereas
Journal Title: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research
Volume: 31
Issue: 6
Publisher: Unknown  
Date Published: 2016
Start Page: 1128
End Page: 1136