Serum Levels of Adiponectin and Vitamin D Correlate with Activity of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which numerous cells and mediators affect inflammatory conditions and disease severity. To compare the serum levels of adiponectin, vitamin D, copper, and zinc in patients with RA and to investigate the relationship between these parameters and RA severity. Ninety patients with RA and 30 healthy controls participated in this cross-sectional case-control study between November 2016 and April 2017; according to the ACR/EULAR criteria for RA. Serum levels of adiponectin were determined by ELISA; copper and zinc by colorimetric spectrophotometry; and vitamin D by HPLC. Kruskal-Wallis and Spearman tests were performed using SPSS software and data were depicted by GraphPad Prism software. Compared with healthy controls, the serum level of adiponectin was significantly increased, whereas vitamin D was significantly decreased in patients with RA. Adiponectin and vitamin D levels were inversely correlated in RA subgroups (P < 0.001, r = - 0.410). Adiponectin and vitamin D correlated with RA severity. Furthermore, no significant difference was found in copper and zinc levels between RA groups and controls. The definitive roles of adiponectin, vitamin D, copper, and zinc are not completely determined in RA development. Based on disease activity, these parameters can modulate inflammatory conditions, thus they have the potential to be used as promising therapeutic biomarkers to follow up the severity of disease, as well as the progression and treatment success in patients with RA.