The etiologies of chronic urticaria (CU) in childhood remains incompletely understood because of limited data in children. The objective of this study was to examine some of the possible etiologies of CU in children by focusing on the functional autoantibody to FcepsilonRIalpha and IgE, thyroid autoimmunity, urticarial vasculitis, parasitic infestation and food allergy. Children 4-15 yr of age with CU were investigated for complete blood count, erythrocyte sedimentation rate (ESR), antinuclear antibody (ANA), CH(50), free-T4 (FT(4)), thyroid stimulating hormone (TSH), anti-thyroglobulin and anti-microsomal antibody, autologous serum skin test (ASST), skin prick tests (SPT) for foods, food challenges, and stool examination for parasites. Ninety-four children who met the criteria for CU were recruited. Patients with physical urticaria were excluded. Eosinophilia and elevated ESR were found in 23% and 13%, respectively. High ANA titers were found in 2%. None of these patients had clinical features of urticarial vasculitis, abnormal CH(50) level, abnormal TSH and FT(4). Anti-thyroglobulin and anti-microsomal antibodies were not detected. Positive ASST was found in 38%. There were no differences in medication requirement and CU remission between patients with positive and negative ASST. Parasites were found in 5% without clinical correlation. SPT to foods was positive in 35%. Positive food challenges were found in six/nine patients with positive history of food allergy and two/seven patients with negative history. Food avoidance was beneficial to the subgroup of patients with positive history of food allergy only.

No abstract

Specific allergy to Pm or Mr was confirmed by food challenges. SPT using crude extracts and the PTP test are useful tools for screening shrimp sensitization before a food challenge. The predictive probability of SPT is helpful where a food challenge is not feasible.