Clinical Significance of Fecal Calprotectin for Evaluating Mucosal Inflammation with IgA Vasculitis

IgA vasculitis is the most common systemic small vasculitis in children. Its major clinical manifestations are palpable purpura, arthritis and arthralgias, gastrointestinal involvement, and renal manifestations. Regarding gastrointestinal manifestations, steroids are effective in reducing abdominal pain. However, exacerbation of gastrointestinal manifestation is frequently experienced when the steroid dose is being tapered. Thus, reliable biomarkers for gastrointestinal mucosal inflammation are needed. We report the case of a 4-year-old girl with abdominal-type IgA vasculitis. During the clinical course, we used several markers, such as fecal immunochemical test, fecal α₁-antitrypsin and calprotectin. When fecal immunochemical test showed negative results and fecal α₁-antitrypsin value returned to the normal range, corresponding to her abdominal pain improvement, fecal calprotectin levels remained high. This suggests that fecal calprotectin is more sensitive for evaluating mucosal inflammation than other markers. It could be a useful marker for mucosal inflammation in IgA vasculitis.