SOURCE: Bae SC, Lee YH. Postgrad Med 2017;129:531-537.

Clinicians who see patients with inflammatory bowel disease (IBD), such as Crohn’s disease or ulcerative colitis, likely will be familiar with using fecal calprotectin levels as a diagnostic tool. Indeed, some experience suggests that because of “skip areas” observed in IBD, fecal calprotectin may be as or even more sensitive to diagnose IBD than endoscopy. Calprotectin also is measurable in plasma and synovial fluid, and has been recognized recently as a good marker of disease activity in rheumatoid arthritis (RA).

There are several validated metrics for assessment of disease activity in RA, including C-reactive protein (CRP) and Disease Activity in 28 Joints (DAS28). Bae and Lee performed a meta-analysis of RA patients (n = 849) to evaluate the correlation of calprotectin with CRP and DAS28. Significant positive correlations were demonstrated. Common treatment for RA patients includes biologic agents such as TNF-inhibitors. Calprotectin levels have been demonstrated to be good indicators of disease activity in patients on TNF treatment. Hence, calprotectin may provide a metric for confirmation of optimized control of RA, providing additional insight into disease activity beyond clinical symptoms alone.