[Diagnosis of food allergy in children].

In infants, food allergies are usually manifested by digestive symptoms and the most commonly involved antigens are cow's milk proteins. Although the full range of clinical manifestations of cow's milk protein sensitivity may occur as soon as birth, enteropathy is the most common pattern. As the infant grows, cow's milk antigens lose their predominance as the causative agents of adverse reactions to foods. All foods may be involved, and consequently diagnostic evaluation is more difficult. The gastrointestinal tract is no longer the preferred target organ and symptoms of food allergy may be systemic, cutaneous or, in a smaller number of cases, respiratory. History taking is the first step of the diagnostic process and provides very valuable data. Skin tests and in vitro detection of specific IgE antibodies are then performed. Results of the skin tests may help select the most appropriate in vitro tests. Diagnosis is always established by diet modifications using diets free of the suspected offending food, followed by challenge tests. Intestinal permeability tests provide a noninvasive means for demonstrating intestinal reactivity.