Association Between Serum 25-Hydroxyvitamin D Levels and Neuropathic Pain Features in Adults Presenting with Musculoskeletal Pain: A Cross-Sectional Study.

BACKGROUND/OBJECTIVES: The association between vitamin D status and neuropathic pain in musculoskeletal disorders remains uncertain. This study examined the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and neuropathic pain features in adults with musculoskeletal pain. METHODS: This single-center analytical cross-sectional study included 300 adults aged 18-79 years who presented between June and December 2024. Participants were classified as vitamin D deficient (<20 ng/mL; n = 105), insufficient (20-<30 ng/mL; n = 117), or sufficient (≥30 ng/mL; n = 78). Neuropathic pain was assessed using DN4, LANSS, painDETECT, and the Short-Form McGill Pain Questionnaire. Multivariable logistic regression adjusted for age, sex, body mass index, diabetes mellitus, inflammatory rheumatic disease, cervical/lumbar discopathy, and fibromyalgia. RESULTS: Neuropathic pain scores increased as 25(OH)D levels decreased. DN4 positivity occurred in 53.3%, 43.6%, and 25.6% of the deficient, insufficient, and sufficient groups, respectively (p < 0.001). Compared with sufficiency, vitamin D deficiency and insufficiency were associated with DN4 positivity (adjusted odds ratio [aOR] 3.53, 95% confidence interval [CI] 1.76-7.08; and aOR 2.38, 95% CI 1.22-4.64, respectively). Each 10 ng/mL decrease in 25(OH)D was associated with 46% higher odds of DN4 positivity (aOR 1.46, 95% CI 1.14-1.86). Similar associations were observed for LANSS and painDETECT ≥13 and persisted in sensitivity analyses. CONCLUSIONS: Lower 25(OH)D levels were associated with higher neuropathic pain scores and more frequent positive screens. The cross-sectional design, modest effect sizes, and unmeasured supplementation and calcium-parathyroid hormone variables preclude conclusions regarding causality, diagnostic utility, or treatment efficacy.