IL34 and rheumatoid arthritis: A case-control study containing with 100 RA patients and 59 healthy controls not only measured serum IL-34 levels in RA patients and healthy controls but also observed that serum IL-34 levels were significantly greater in RA patients than in healthy controls (603.5 [123.3–1673.0] vs. 152.0 [92.0–234.0] pg/ml) [15].