[Prevalence of chronic urticaria following the ingestion of food additives in a third tier hospital].

We studied 40 patients with the clinical diagnostic of chronic urticaria from January to June, 1995 and excluded 4 patients who did not fulfilled the entry criteria. 29 women and 7 men with age from 4 to 62 years old. We performed a basic clinics history and the oral challenge tests (PRO) included Tartrazine (Ta), Sodium Metabisulfite (MS), Potasium Metabisulfite (MP) and Sodium Bisulfite (BS) in consecutive days with increasing doses unless an adverse reactions appear. Other tests included Skin Prick tests for food (PC), complete blood counts, coprology and immunology tests (IgE, IgA, IgM, IgG, C3, C4, Cel LE and ANA) and paranasal sinus X Ray. 63.8% (23/36) had positive PRO. 47.2% (17/36) positives to Ta,, 36.1% (13/36) to MS, 33.3% (12/36) to BS and 30.5% (11/36) to MP. 72.2% (26/36) had positive PC to one or more foods, 65.3% (17/26) besides had positive PRO. 41.1% (7/17) of the patients who had positive PRO and positive PC to foods had sinusitis. One patient (0.23%) had palpebral angioedema with PRO. The prevalence was 3.1%. Ta was the additive that cause more reactivity. It is possible to find reactivity to one or more additives in a patient with chronic urticaria.