Our metabolomic analysis shows a distinct metabolic signature in RA patients with high ADA activity and low ADA activity when compared to healthy controls; altered metabolic levels of hydroxyisocaproic acid, 1-methyl histidine, inosine, fructose-6-phosphate, and hexose phosphate can be added to the existing biochemical tests as markers that can be used as indicators of increased disease activity in RA patients. The gene discussed is ADA; the disease is rheumatoid arthritis.