Investigation and diagnosis of lifethreatening allergies in childhood
Life-threatening allergies often present difficult diagnostic challenges to health practitioners managing children. They are a source of great anxiety to parents and children and require accurate assessment and careful management. In recent decades there has been a real increase in true food and drug allergies affecting children across the age spectrum, from well-nourished ones to those infected with HIV. Although the most severe life-threatening allergies in children most often result from food and drug hypersensitivities, severe allergic reactions with life-threatening consequences are also encountered after exposure to latex, insect venoms, vaccines, immunotherapy, certain aero-allergens and certain food and drug preservatives. In high-risk children life-threatening reactions may also follow exercise or exposure to cross-reacting allergens. The principle of taking a careful history, details of the events and exposure before the reaction and before embarking on blood tests or other investigations, applies to all life-threatening allergies. There are a number of useful new diagnostic tests for evaluating life-threatening reactions. These include nonspecific tests, such as the mast cell tryptase test, and specific tests, including the Immunocap radio-allergosorbent test (RAST), cellular activated sulphido-leukotriene release test (CAST), titrated specific skin-prick testing and controlled challenge tests. Assessment of risk, level of exposure, inadvertent exposure and prevention of subsequent reactions are important components of the comprehensive management of these children.