Vitamin D deficiency Associates with Disease Severity in Rheumatoid Arthritis Patients

Abstract

Vitamin D considered as a key player in various autoimmune disorders, such as rheumatoid arthritis, due to its immunological modulatory effect. Together with Anti-double stranded DNA (Anti-dsDNA), Anti-cyclic citrullinated peptide (Anti-CCP) is considered among the indicators of the disease severity in rheumatoid arthritis. The present study aimed to measure the level of vitamin D in RA patients besides measuring anti-dsDNA, anti-CCP, RF, complete blood count (CBC) and Erythrocyte Sedimentation Rate (ESR) for comparing it with its corresponding level in healthy control group. This study was a descriptive cross-sectional study involving sequential RA patients who visited the Rheumatology clinic for outpatients during  three-months period starting from July 2018, at the Baghdad Teaching Hospital. Sixty individuals (30 RA patients and 30 age and gender matched healthy control) were enrolled in this study. Blood samples were collected and serum levels of anti-dsDNA, 25-hydroxy vitamin D (25[OH]), anti-CCP and RF besides C3, C4, CBC and ESR were measured. A highly significant decrease was displayed in the mean level of vitamin D in RA patients (18.67±17.70 ng/mL) when compared to its level in the control group (35.07 ±3.71 ng/mL), (normal value: 20 and 40 ng/mL), whereas, anti-dsDNA level normal value: (<30.0 IU/mL) was significantly increased in RA patients (122.27±65.89 IU/ml) as compared to its mean level in the control group (17.77±3.56 IU/ml) with an inverse relationship between anti-dsDNA levels vitamin D levels in RA patients. No statistical difference noted in C3 and C4 levels between patients and control groups. Rheumatoid arthritis patients with positive RF had statistically higher anti-CCP (normal value: less than 20 U/ml) than those with negative RF (39.83±11.449 vs 21.67±4.658 u/ml). As expected, a highly significant increase was observed in ESR of patients when compared to that of the control. In addition, an alteration was noted in some circulating blood cells count.