Fecal calprotectin as a marker of gastrointestinal involvement in pediatric Henoch–Schönlein purpura patients: a retrospective analysis

BACKGROUND: Henoch–Schönlein purpura is a type of systemic vasculitis found in children. Its prognosis is usually good; however, recurrence is relatively common. If the intestines are affected, severe complications could arise. Here, we investigated the value of fecal calprotectin in the early screening of Henoch–Schönlein purpura and as a useful factor for predicting gastrointestinal manifestations. METHODS: We retrospectively reviewed the medical records of pediatric patients who were diagnosed with Henoch–Schönlein purpura and underwent fecal calprotectin testing during the acute phase. The patients were categorized into gastrointestinal involvement and non-gastrointestinal involvement groups based on their clinical symptoms. Moreover, gastrointestinal involvement was categorized as follows: upper gastrointestinal tract involvement (up to the duodenum) and lower gastrointestinal tract involvement (from the terminal ileum). RESULTS: A total of 69 patients were diagnosed with Henoch–Schönlein purpura and underwent fecal calprotectin testing. Among them, 40 patients (58.0%) showed signs of gastrointestinal involvement. The gastrointestinal involvement group had higher fecal calprotectin levels (379.9 ± 399.8 vs. 77.4 ± 97.6 mg/kg, P = 0.000). There were no significant differences in the recurrence of Henoch–Schönlein purpura symptoms or gastrointestinal symptoms. The cut-off value to identify gastrointestinal involvement was 69.10 mg/kg (P < 0.01). Patients with fecal calprotectin levels of > 50 mg/kg showed more frequent gastrointestinal involvement (77.8% vs. 20.8%, P = 0.000) and more severe gastrointestinal symptoms. Significant differences in abdominal pain duration, Henoch–Schönlein purpura clinical score, and abdominal pain severity were observed (P = 0.002, P = 0.000, and P = 0.000, respectively). Additionally, fecal calprotectin levels were significantly higher in patients with lower gastrointestinal tract involvement (214.67 ± 150.5 vs. 581.8 ± 510.1 mg/kg, P = 0.008), and the cut-off value was 277.5 mg/kg (P < 0.01). CONCLUSION: Fecal calprotectin testing is useful for identifying gastrointestinal involvement in pediatric Henoch–Schönlein purpura patients.