Octeia 25 hydroxy vitamin d

The concentration of 25-hydroxyvitamin D (25(OH)D) was measured in serum samples using an ELISA (OCTEIA^® 25-Hydroxy Vitamin D, Immuno Diagnostic Systems, Ltd., Boldon, UK). The intra-assay CV for the ELISA method was 5.9%. This ELISA assay is used for the quantitative determination of 25(OH)D, further details of which have been described previously [24 (link)]. The quality and accuracy of serum 25(OH)D analysis in our laboratory was assessed and assured on an ongoing basis by participation in the Vitamin D External Quality Assessment Scheme (DEQAS, Charing Cross Hospital, London, UK).

Serum concentrations of 25(OH)D were measured by using an in vitro diagnostic enzyme immunoassay kit OCTEIA 25-Hydroxy Vitamin D (Immunodiagnostic Systems, Boldon, United Kingdom) according to the manufacturer’s instructions. The reported analytic sensitivity of the immunoassay was 6.8–380 nmol/L.

Blood samples in boxes were collected according to the time of collection. A biochemical analysis was performed within 24 h by trained technicians and serum was stored at −80°C for future analysis. Serum 25(OH)D concentration was measured by the enzyme‐linked immunosorbent assay (ELISA) kit OCTEIA 25‐Hydroxy vitamin D (Immunodiagnostic Systems, Boldon, United Kingdom) according to the manufacturer's instructions. More than 10% results were selected to repeat for quality control at random. The coefficients of variation (CV) for the 25(OH)D assay determined at assay verification were as follows: interassay CV, 8.7% at a concentration of 49.5 nmol/L and 3.6% at 103 nmol/L (intraassay CV, 2.8% and 1.3%, respectively), and the reported analytic sensitivity of the immunoassay was 6.8–380 nmol/L. The condition of blood sampling is random. The blood sample is kept in dark place. This kit has obtained the US Centers for Disease Control and Prevention (CDC) Vitamin D Standardization Certification (VDSP; Sempos et al., 2017 (link)).