title: The Road Not So Travelled: Should Measurement of Vitamin D Epimers during Pregnancy Affect Our Clinical Decisions?
abstract: Observational studies suggest an adverse effect of maternal hypovitaminosis D during pregnancy. However, intervention studies failed to show convincing benefit from vitamin D supplementation during pregnancy. With analytical advances, vitamin D can now be measured in ten forms-including as epimers-which were thought to be biologically inactive, but can critically impair immunoassays. The aim of this commentary is to highlight the potential clinical and analytical significance of vitamin D epimers in the interpretation of vitamin D roles in pregnancy. Epimers may contribute a considerable proportion of total vitamin D-especially in the neonate-which renders the majority of common assays questionable. Furthermore, epimers have been suggested to have activity in laboratory studies, and evidence suggests that the fetus contributes significantly to epimer production. Maternal epimer levels contribute significantly to predict neonate circulating 25-hydroxyvitamin D concentrations. In conclusion, the existence of various vitamin D forms (such as epimers) has been established, and their clinical significance remains obscure. These results underscore the need for accurate measurements to appraise vitamin D status, in order to understand the current gap between observational and supplementation studies on the field.
authors.affiliation: Division of Endocrinology and Metabolism, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA Hospital, 55535 Thessaloniki, Greece. karraspiros@yahoo.gr.
authors.forename: Spyridon N
authors.initials: SN
authors.lastname: Karras
authors.affiliation: Division of Endocrinology and Metabolism, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA Hospital, 55535 Thessaloniki, Greece. kalmanthou@yahoo.gr.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Kotsa
authors.affiliation: Division of Endocrinology and Metabolism, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA Hospital, 55535 Thessaloniki, Greece. elena-angeloudi@hotmail.com.
authors.forename: Elena
authors.initials: E
authors.lastname: Angeloudi
authors.affiliation: Division of Endocrinology and Metabolism, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA Hospital, 55535 Thessaloniki, Greece. pzempeka@auth.gr.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Zebekakis
authors.affiliation: School of Life Sciences, Pharmacy and Chemistry, Kingston University London, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK. D.Naughton@kingston.ac.uk.
authors.forename: Declan P
authors.initials: DP
authors.lastname: Naughton
mesh_terms: D002853:Chromatography, Liquid; D000066491:Clinical Decision-Making; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D064887:Observational Studies as Topic; D011247:Pregnancy; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000008:administration & dosage / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis
chemical_list: D014807:Vitamin D
keywords: epimers; pregnancy; vitamin D