title: 25-Hydroxyvitamin D: analysis and clinical application.
abstract: 25-Hydroxyvitamin D (25-OHD) is one of the most popular tests requested by clinicians nowadays because in addition to bone diseases, many non-skeletal disorders have been suggested to be linked to vitamin D deficiency or insufficiency. Methodologies used in clinical laboratories include competitive vitamin D protein binding assays (CPBA), immunoassays, high performance liquid chromatography (HPLC), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this review article, we introduce the basic metabolism and physiology of vitamin D, key issues in the methods for 25-OHD measurement currently used in most clinical laboratories, and clinical applications of 25-OHD testing. We conclude that although the methodologies for 25-OHD testing have improved significantly, considerable bias between different methods and laboratories still exists. Therefore, standardization of the method is critical. The optimal 25-OHD levels should be determined based on the standardized method. Also, more studies are needed to further determine the relationship between vitamin D deficiency or insufficiency and non-skeletal diseases as well as daily vitamin D dose requirement for reducing the risk of non-skeletal diseases.
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Zengliu
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Satya Nandana
authors.initials: SN
authors.lastname: Narla
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA. Electronic address: zhuyu@musc.edu.
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D019963:Clinical Chemistry Tests; D004194:Disease; D004305:Dose-Response Relationship, Drug; D006801:Humans; D012449:Safety; D014807:Vitamin D / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D014808:Vitamin D Deficiency
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-Hydroxyvitamin D; Clinical application; Laboratory analysis