DETERMINATION OF VITAMIN D METABOLITES AND THEIR EPIMERS IN OBESE EMIRATI POPULATION
Abstract
Vitamin D deficiency is a global issue, and despite all-year-round sunshine, it is a big problem in the UAE. Obesity or overweight refers to an accumulation of excessive fat that may harm health; so, it is considered a worldwide health concern. The accurate measurement of vitamin D active forms is a problematic issue. The aim of this study was to develop and validate a UHPLC-MS/MS method for the determination of vitamin D metabolites and their epimers and then apply the new method for the determination of vitamin D levels in the obese Emirati population. The vitamin D epimers and other metabolites were determined by UHPLC-MS/MS system, model 8060. The methods include the collection of blood samples from 729 individuals, divided into 277 baselines (vitamin D deficient volunteers), 277 follow-ups (supplemented volunteers), and 175 healthy volunteers, extraction of vitamin D and epimers from plasma samples, method development, and validation. The vitamin D metabolites and their epimers have been separated by UHPLC-MS/MS instrument. The method validation criteria were found in an acceptable range. Epimers of vitamin D metabolites were found to cause an overestimation of 25OHD and give false-positive results in the obese Emirati population. The results showed that baseline, follow-up, and healthy volunteers are deficient in vitamin D's major metabolites. UHPLC-MS/MS has superior selectivity. This new vitamin D blood test has been successfully applied to estimate the vitamin D and epimer levels in the obese Emirati population, and the results showed that the current vitamin D estimation methods are overestimating the actual results. This new method will have far-reaching applications in any future clinical studies.