Associations between functional constipation and non-IgE- mediated food allergy in infants and children

The non-IgE-mediated food allergy (non-IgE-FA) is less prevalent than IgE-mediated food allergy, and their relationship with functional constipation (FC) needs to be clarified.A total of 305 infants and children with constipation treated in the Department of Pediatric Gastroenterology, Children's Hospital of Nanjing Medical University, from July 2020 to December 2021 were included in this study. Four cases with organic lesions were excluded. Among 301 diagnosed with FC, according to ROME IV criteria, 81 cases with allergy-related indicators were further evaluated for food allergy by food-specific IgG antibody test, allergen- specific IgE antibody detection, skin prick test, and food avoidance and reintroduction.A total of 45 cases with FC were diagnosed with food allergy, and the incidence rate was 15%. Among the 45 patients, 35 cases (77.8%) had FC with non-IgE-FA. The main clinical symptoms or signs included anal fissure, abdominal pain, and pain during defecation. The most prevalent allergic foods were cow's milk, eggs, fish, and shrimp. Ten (22.2%) cases reported FC with mixed food allergy, including both non-IgE-mediated and IgE-mediated food allergy. This study focused on non-IgE-mediated food allergy-related FC.Our results showed that the incidence of food allergy in infants and children with FC was 15%, which was mainly mediated by non-IgE-FA. The main clinical symptoms or signs in these cases included anal fissure, abdominal pain, and pain during defecation, and the main allergens included milk, eggs, fish, and shrimp.