Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis

Background Vitamin D deficiency is prevalent in children with juvenile idiopathic arthritis (JIA). Prevention and supplementation with vitamin D may help improve diseases. Understanding subtype-specific variations in vitamin D levels before initiating treatment could provide valuable insights for early monitoring. Methods This study included 236 newly diagnosed, untreated children with active JIA who were admitted to Chongqing Medical University Children's Hospital between May 2019 and April 2024. Demographic and clinical characteristics, inflammatory markers, vitamin D levels, bone metabolism, and bone mineral density were retrospectively reviewed. Univariable and multivariable analyses were performed to identify factors affecting vitamin D levels and assess intergroup differences among JIA subtypes. Results Univariable analysis showed positive correlations of calcium and phosphorus levels with vitamin D levels, while body weight, body mass index, normalized erythrocyte sedimentation rate (ESR), and IL-6 exhibited negative correlations ( p  < 0.05). Multivariable analysis identified reduced bone mineral density, normalized ESR, and normalized C-reactive protein (CRP) as significant variables associated with vitamin D levels. The stratified analysis revealed notable differences in gender, weight, and bone density across JIA subtypes. Conclusion Vitamin D deficiency is associated with inflammation in JIA. Findings from the multivariate generalized linear regression model emphasize the distinct patterns of vitamin D levels and their influencing factors across JIA subtypes, offering critical insights for early monitoring and informed clinical decision-making before treatment. Trial registration The study was registered on chictr.org.cn on June 12, 2022 (ID: ChiCTR2200060798).