2976-LB: Association between Serum 25-Hydroxyvitamin D and Cardiovascular–Kidney–Metabolic Syndrome

Introduction and Objective: To investigate the association between vitamin D and cardiovascular-kidney-metabolic syndrome (CKM). Methods: A total of 16,285 eligible participants were included based on data from the National Health and Nutrition Examination Survey (NHANES) 2001-2018. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by radioimmunoassay for 2001-2006 and by standardized liquid chromatography-tandem mass spectrometry (LC-MS/MS) for 2007-2018. Regression calibration was applied to harmonize 25(OH)D values across survey cycles. CKM stages (0-4) were defined according to the 2023 American Heart Association (AHA) criteria. Weighted multinomial logistic regression and restricted cubic splines were used to explore the association between 25(OH)D and CKM stages, with adjustment for age, sex, race/ethnicity, education level, marital status, smoking, and alcohol consumption. Results: In the study population, the proportions of vitamin D sufficiency (>75 nmol/L), insufficiency (50-75 nmol/L), and deficiency (<50 nmol/L) were 33.8%, 39.9%, and 26.3%, respectively. Compared with vitamin D sufficiency, vitamin D deficiency was significantly associated with higher risk of CKM stages 1-4, with adjusted odds ratios (95% confidence intervals) as follows: stage 1, 1.32 (1.03-1.69); stage 2, 2.55 (2.07-3.15); stage 3, 2.62 (1.87-3.68); and stage 4, 3.36 (2.52-4.48). Restricted cubic spline analysis revealed a linear dose-response relationship between 25(OH)D and CKM stage 1 (nonlinear *P* = 0.633), whereas nonlinear L-shaped or J-shaped curves were observed for 25(OH)D and CKM stages 2-4 (nonlinear *P* < 0.01). Conclusion: Vitamin D deficiency is independently associated with the progression of CKM syndrome, and the strength of this association increases with advancing disease stage. Disclosure A. Abudukeranmu: None. Y. Zhuang: None. Y. Chu: None. Y. Li: None. H. Fan: None. J. Chang: None. M. Li: None. Z. Song: None. H. Zhu: None. Funding This work was supported by the National Natural Science Foundation of China (grant number 81602922); the Tianjin Health Science and Technology Project (grant number TJWJ2023MS059); the Tianjin Key Medical Discipline (Specialty) Construction Project (grant number TJYXZDXK-032A); and the Education and Teaching Research Project of Tianjin Medical University (grant number 2023jxzd03).