Abstract

Introduction: Vitamin D is a fat soluble vitamin. Main source of vitamin D is de novo synthesis in the skin by ultraviolet B rays of sunlight. The active metabolite of vitamin D is the 1,25-dihydroxyvitaminD3(1,25(OH)2 D3),which is regulator of bone and calcium metabolism. It also exerts immunomodulation effect via the nuclear vitamin D Receptor (VDR) expressed in antigen-presenting cells (APC) and activated T/B cells. Rheumatoid arthritis (RA) is an immune-mediated disease, mainly driven by Th1 cells. The characteristic features of the disease are erosive arthritis and joint destruction leading to severe disability and increased mortality. RA affects about 24.5 million people as of 2015. This is between 0.5 and 1% of adults with 5 per 100,000 people newly developing the condition each year. Although the etiology of RA is unknown, various studies suggest that many environmental and genetic factors are responsible for development of RA. A recent study showed the association of dietary and supplemental vitamin D with RA , higher intake of vitamin D was inversely associated with risk of RA. RA is an inflammatory disease characterized by flares and remissions, flares being characterized by pain and swelling of the joints.. Vitamin D deficiency is also known to be associated with diffuse musculoskeletal pain .

Aim: To assess the level of serum vitamin D level in patients of Rheumatoid Arthritis and to establish relationship between serum vitamin D level and disease activity in RA.

Method: Forty patients of RA fulfilling 2010 revised criteria of American college of Rheumatology of RA classification and forty healthy controls were included in the study. Serum vitamin D levels were measured. Disease activity was assessed by DAS-28 score.

Results: Ninety five percent of RA patients were either vitamin D deficient or insufficient while only fifty percent of healthy controls were either vitamin D deficient or insufficient( p value <0.05). Mean serum vitamin D level of patients of RA was (16. 00 ± 8.91 ng/ml) while mean serum  vitamin D level of healthy controls was  (31.5± 14.34ng/ml) and this difference was statistically highly significant (p<0.001). The prevalence of vitamin D deficiency and insufficiency in patients of RA is 62.5% and 32.5% respectively. We concluded vitamin D deficiency is highly prevalent in RA patients and is inversely related with disease activity of RA. There were 6 patients of RA in low disease activity group (DAS 28 score < 3.2) and the mean serum vitamin D level in this group was 30.5±9.81 ng/ml. There were 18 RA patients in moderate disease activity group (DAS 28 score 3.2 - 5.1) and the mean serum vitamin D levels were 16.7±5.97 ng/ml. There were 16 RA patients in high disease activity group (DAS 28 score >5.1) and the mean serum 25(OH) vitamin D level was 9.60±4.30 ng/ml. Patients with high disease activity had significantly lower vitamin D levels in comparison to patients with low or moderate disease activity (p<0.001).

Conclusion: Serum vitamin D levels were significantly low in RA patients than in healthy controls. Vitamin D deficiency was seen in significantly higher no. of patients and there is inverse relation between serum vitamin D levels and disease activity.

Keywords: Serum Vitamin D level, Rheumatoid Arthritis (RA), Disease Activity.