High throughput UHPLC-MS/MS method for the simultaneous quantification of six vitamin D metabolites: application for vitamin D determination in patients after liver or kidney transplantation

An ultra-sensitive and high-throughput trapping-micro-LC-MS method for quantification of circulating vitamin D metabolites and application in multiple sclerosis patients

Quantitative analysis of the biologically-active metabolites of vitamin D (VitD), which are crucial in regulating various physiological and pathological processes, is important for clinical investigations. Liquid chromatography-tandem mass spectrometry (LC-MS) has been widely used for this purpose but existing LC-MS methods face challenges in achieving highly sensitive and accurate quantification of low-abundance VitD metabolites while maintaining high throughput and robustness. Here we developed a novel pipeline that combines a trapping-micro-LC-(T-µLC) with narrow-window-isolation selected-reaction monitoring MS(NWI-SRM) for ultra-sensitive, robust and high-throughput quantification of VitD metabolites in serum samples after derivatization. The selective-trapping and delivery approach efficiently removes matrix components, enabling high-capacity sample loading and enhancing sensitivity, throughput, and robustness. The NWI-SRM further improves the sensitivity by providing high selectivity. The lower limits of quantification (LOQs) achieved were markedly lower than any existing LC-MS methods: 1.0 pg/mL for 1,25(OH)2D3, 5.0 pg/mL for 24,25(OH)2D3, 30 pg/mL for both 25(OH)D2 and 25(OH)D3, all within a 9-min cycle. The method is applied to quantify VitD metabolites from 218 patients with multiple sclerosis. This study revealed negative correlations(r=- 0.44 to - 0.51) between the levels of 25(OH)D2 and all the three D3 metabolites in multiple sclerosis patients.

Accurate Clinical Detection of Vitamin D by Mass Spectrometry: A Review

Vitamin D deficiency is thought to be associated with a wide range of diseases, including diabetes, cancer, depression, neurodegenerative diseases, and cardiovascular and cerebrovascular diseases. This vitamin D deficiency is a global epidemic affecting both developing and developed countries and therefore qualitative and quantitative analysis of vitamin D in a clinical context is essential. Mass spectrometry has played an increasingly important role in the clinical analysis of vitamin D because of its accuracy, sensitivity, specificity, and the ability to detect multiple substances at the same time. Despite their many advantages, mass spectrometry-based methods are not without analytical challenges. Front-end and back-end challenges such as protein precipitation, analyte extraction, derivatization, mass spectrometer functionality, must be carefully considered to provide accurate and robust analysis of vitamin D through a well-designed approach with continuous control by internal and external quality control. Therefore, the aim of this review is to provide a comprehensive overview of the development of mass spectrometry methods for vitamin D accurate analysis, including emphasis on status markers, deleterious effects of biological matrices, derivatization reactions, effects of ionization sources, contribution of epimers, standardization of assays between laboratories.

Effects of Vitamin D supplementation or deficiency on metabolic phenotypes in mice of different sexes

Vitamin D is a steroid hormone precursor that was initially recognized for its important roles in calcium-phosphate homeostasis and bone health. However, the resent prevalence of vitamin D deficiency has highlighted its non-skeletal function, such as its important role in regulating endogenous metabolism. The aim of the present study was to examine the roles of vitamin D supplementation or deficiency on metabolic phenotypes in both male and female mice by using targeted metabolomics analysis. Six weeks old C57BL/6 mice of different sexes were fed with standard chow diet (1000 IU/kg vitamin D3 contained), vitamin D deficient diet (0 IU/kg vitamin D3 contained), or vitamin D enriched diet (10,000 IU/kg vitamin D3 contained) for a total of 14 weeks. Liver pathological analysis showed that vitamin D deficiency caused significant fat deposition in both male and female mice. While vitamin D supplementation was found to improve the accumulation of fat in the liver tissue. Metabolomics analysis indicated that metabolic perturbation related to vitamin D regulation in male mice mainly involved in tricarboxylic acid cycle, fatty acylcarnitine and fatty acid metabolism, sugar metabolism, glutathione metabolism, steroid hormone and pyrimidine metabolism. Based on the criteria of VIP> 1 in OPLS-DA analysis and P < 0.05 in hypothesis test, a total of 62 metabolites and 78 metabolites were found to be significantly changed in VD-deficiency group and VD-supplement group compared with the control group, respectively. While for female mice, the metabolites disturbance mainly involved in fatty acylcarnitine and fatty acid metabolism, TCA, sugar metabolism, folate cycle, methionine cycle, and purine metabolism. A total of 38 and 57 metabolites were found to be significantly changed (VIP>1 and P < 0.05) in VD-deficiency group and VD-supplement group compared with the control group, respectively. Energy metabolism was the most relevant metabolic pathway for vitamin D regulation in both male and female mice. Sex-specific changes of fatty acyl carnitines and dehydroepiandrosterone were observed in the vitamin D supplementation groups. However, most of the energy metabolism related compounds exhibited the same trend in vitamin D supplementation groups of different sexes. Pearson's correlation analysis indicated that vitamin D was significantly correlated (P < 0.05) with the levels of D-fructose 6-phosphate, D-glucose 1-phosphate, D-glucose 6-phosphate, DL-pyroglutamic acid, 2-oxoglutarate, L-glutamic acid, and fumarate, which were all involved in the sugar metabolism pathway. The results achieved in this study demonstrated that vitamin D significantly regulated the metabolism of lipid and sugar, and the regulation showed a certain sex specificity.

Analysis of Vitamin D Components in Serum of Minors by UHPLC-MS/MS

Serum 25-hydroxyvitamin D [25(OH)D] concentration represents the body's reserves of vitamin D, which is mostly used by clinicians to evaluate the storage status of vitamin D in the body. The present study aimed to investigate the serum vitamin D components in different health status of minors to correctly evaluate the vitamin D storage in vivo. A total of 2,270 minors were included in the study, which was divided into healthy group (1,204 cases) and disease group (1,066 cases, including 270 short stature, 433 respiratory infections, 175 malnutrition and 188 tic disorder subjects). The levels of 25-hydroxyvitamin D₂ [25(OH)D₂] and 25-hydroxyvitamin D₃ [25(OH)D₃] were measured by UHPLC-MS/MS in all subjects, and the 25(OH)D₃ activity equivalents [25(OH)D₃-AE] and 25(OH)D were calculated. In addition, the 3-epi-25-hydroxyvitamin D₃ [3-epi-25(OH)D₃] concentrations of 278 subjects (including 147 healthy and 131 disease subjects) were measured by random sampling. 25(OH)D₂, 25(OH)D₃, 25(OH)D and 25(OH)D₃-AE levels in disease group were significantly lower than those in healthy group (p<0.001). According to the level of 25(OH)D, the sufficiency of vitamin D [25(OH)D≥30 ng/mL] was 65.4% in healthy group and 50.5% in disease group. When the 25(OH)D₂ activity was converted into 25(OH)D₃-AE, 53.2% of the patients in the healthy group had sufficiency vitamin D, and 39.1% in the disease group. The 3-epi-25(OH)D₃ level in the disease group was significantly lower than that in the healthy group (p<0.001). Not only the 25(OH)D, but also the both of 25(OH)D₂ and 25(OH)D₃ levels may overestimate the vitamin D status in subjects. For accurate evaluation, at least the serum levels of 25(OH)D₂, 25(OH)D₃ and 3-epi-25(OH)D₃ should be determined simultaneously.