Jarlborg M, Courvoisier DS, Lamacchia C, et al. - The present study was conducted to evaluate the correlation of serum calprotectin with disease activity and severity in rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), and psoriatic arthritis (PsA). Researchers assessed serum calprotectin in patients with RA, axSpA, and PsA from the prospective Swiss Clinical Quality Management registry. They applied asymptomatic first-degree relatives of RA patients as healthy controls (HC). This study enrolled a sum of 1,729 individuals [RA = 969, axSpA = 451, PsA = 237, and HC = 72]. This large study indicates the correlation of serum calprotectin levels with disease activity in both RA and axSpA, but not in PsA.