Background/Purpose: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that can affect multiple organs. Vitamin D levels have been associated with disease activity in SLE, and the neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential marker of inflammation in autoimmune conditions, including SLE. However, the relationship between vitamin D and NLR in SLE patients remains unclear and requires further investigation.Objective To evaluate the association between serum vitamin D levels and the neutrophil-to-lymphocyte ratio (NLR) in patients with SLE.

Methods: We performed a cross-sectional study including 188 patients with systemic lupus erythematosus (SLE), recruited from a specialized outpatient clinic. All individuals met the 2019 EULAR/ACR classification criteria for SLE. Clinical and laboratory data were extracted from electronic medical records (SLEDAI-2K scores, comorbidities, current treatments, and serum 25-hydroxyvitamin D [25(OH)D] levels. The NLR was calculated using absolute counts from complete blood counts obtained on the same day. Data distribution was assessed using the Kolmogorov–Smirnov test. Group comparisons were performed using the Student’s t-test or Mann–Whitney U test, as appropriate. The relationship between vitamin D levels and NLR was evaluated through Spearman’s rank correlation and multivariable linear regression, adjusting for potential confounders. Statistical significance was set at p < 0.05. Analyses were conducted using STATA MP-Parallel Edition 17.0.

Results: The description of the main demographic, clinical, comorbidity, and analytical variables, along with their association with vitamin D levels (treated as a continuous variable), is presented in Table 1. Serum vitamin D levels were inversely correlated with NLR (r = –0.195; p = 0.024). Patients with organ damage had significantly lower vitamin D levels compared to those without (28.6 ± 10.2 vs. 33.3 ± 9.8 ng/mL; p = 0.008). A trend toward lower vitamin D levels was observed in patients with diabetes (p = 0.048). No significant differences were found regarding disease activity, sex, or other clinical manifestations. In the multivariable regression analysis, log-transformed vitamin D was significantly negatively associated with NLR (coef. -1.40, p = 0.002), indicating that higher vitamin D levels are linked to lower NLR. However, no significant associations were found between NLR and other variables sex, age, disease activity (SLEDAI2K), or organ damage (Table 2).

Conclusion: Vitamin D levels are inversely associated with the neutrophil-to-lymphocyte ratio in SLE patients, suggesting that vitamin D may play a role in immune modulation. Further research is necessary to explore the potential therapeutic effects of vitamin D in lupus management.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/vitamin-d-deficiency-and-its-relationship-with-inflammatory-biomarkers-in-sle-a-focus-on-neutrophil-to-lymphocyte-ratio/