Calprotectin levels in children with enthesis-related arthritis (ERA), arthritis controls (oligoarticular and polyarticular juvenile idiopathic arthritis), noninflammatory controls, and disease controls (unrelated CTD). Calprotectin levels in children with enthesis-related arthritis (ERA), arthritis controls (oligoarticular and polyarticular juvenile idiopathic arthritis), noninflammatory controls, and disease controls (unrelated CTD). MATTHEW L. STOLL et al. J Rheumatol 2011;38:2274-2275 ©2011 by The Journal of Rheumatology