Abstract:Objective To analyze serum 25-hydroxyvitamin D［25(OH)D］ and plasma interleukin-6 (IL-6) levels in patients with rheumatoid arthritis (RA) and their clinical significance. Methods Ninety-nine RA patients treated in the First Affiliated Hospital of Bengbu Medical College from September 2019 to February 2021 were selected as the research group. According to the 28 joint disease activity (DAS28) scores, they were divided into high disease activity group (group H), moderate disease activity group (group M), low disease activity group (group L), and disease remission group (group R), 68 cases of healthy physical examination at the same period were selected as the control group. Chemiluminescence method was used to detect 25(OH)D and IL-6 levels in each group of subjects. Results The 25(OH)D levels of the control group, group R, group L, group M, and group H decreased in sequence, and the IL-6 level increased in sequence. The differences among the groups were statistically significant (P＜0.05). 25(OH)D was significantly negatively correlated with IL-6 level and DSA28 score (r=-0.746, -0.787, P＜0.01); IL-6 level was significantly positively correlated with DSA28 score (r=0.886, P＜0.01). 25(OH)D level was significantly negatively correlated with D-dimer (D-D), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), anti-cyclic citrullinated polypeptide (CCP) antibody, joint swelling number (SJC), joint tenderness number (TJC) (P＜0.01). IL-6 levels was significantly positively correlated with D-D, ESR, CRP, anti-CCP antibodies, SJC and TJC (P＜0.01). Conclusion The level of 25(OH)D in the peripheral blood of RA patients decreases, and the level of IL-6 increases. The combined monitoring of the two can make a more reliable clinical judgment on the degree of RA disease activity.