Development and validation of a UPLC-MS/MS assay for serum choline and phosphocholine with a pilot application to obesity.

The rising global burden of obesity underscores the need to better characterize metabolic alterations associated with this condition. Choline (Cho) and its derivative phosphocholine (ChoP) are key intermediates in phospholipid metabolism, yet their relationships with obesity remain unclear. In this study, we established and validated a UPLC-MS/MS method for quantifying serum Cho and ChoP, and investigated their associations with obesity and fasting glucose in a pilot human cohort. Serum samples from 62 participants (obese vs. nonobese) were analyzed. The primary analysis compared metabolite levels between groups, and key secondary analyses included Pearson correlations with fasting glucose and receiver operating characteristic (ROC)-based discrimination; two-sample Mendelian randomization (MR) was conducted using external GWAS summary statistics. Obese individuals had lower ChoP levels and ChoP/Cho ratios. ChoP and the ChoP/Cho ratio were inversely associated, and Cho was positively associated, with fasting glucose. ChoP showed modest discriminative ability for obesity, and MR suggested that higher ChoP levels may be related to a lower risk of obesity. Overall, we validated a UPLC-MS/MS assay for serum Cho and ChoP, and our findings indicate that ChoP and the ChoP/Cho ratio are linked to obesity and glucose status.