Correlation of Serum Vitamin C Level and Serum Uric Acid with Vitamin D Level in a Sample of Iraqi Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is an autoimmune disease of an unknown etiology and, according to recent studies, vitamin D, vitamin C, and uric acid may all play an important role in the pathophysiology of RA. This cross-sectional study aims to investigate the correlation between the levels of vitamin C and uric acid with vitamin D level in 110 patients with RA who were divided into three groups depending on their serum 25-hydroxyvitamin D (25(OH)D) level. The results revealed that only 27.27% of our RA patients had sufficient serum 25(OH)D (≥ 30 ng/mL), whereas 72.73% of RA patients had deficient or insufficient vitamin D levels (< 30 ng/mL). In females, the percentage of those with vitamin D level < 30 ng/mL was higher (63.75%) than that in males (36.25%). According to different levels of vitamin D in RA patients’ groups, a significant decrease in the level of vitamin C (p = 0.0001) was observed while a non-significant difference was found in the level of serum uric acid (p = 0.527). Meanwhile, no significant correlations were observed (P > 0.05) between levels of vitamin C and uric acid with vitamin D level in patients with RA. On the other hand, a negative correlation between serum vitamin C level and uric acid level was found (P = 0.0001), which indicates RA patients suffered from vitamin C deficiency regardless of the level of vitamin D and they had hyperuricemia which had a negative correlation with vitamin C.