How to Determine Thresholds Clinically

An individual threshold or a minimum eliciting dose (MED) is clinically determined by a titrated, double-blind, placebo-controlled, food challenge. A suitable challenge meal is usually of low fat content for minimal interference with allergen uptake and should be adequately blinded. Challenges are usually performed in a hospital setting. The medical staff in charge have to be specifically trained in early recognition of allergic symptoms, and more importantly in the treatment of a severe, even anaphylactic reaction that might occur under provocation. Challenges usually start with very low doses (μg range in terms of food protein) and the doses are steadily increased at intervals of 20-30. min up to a dose which equals a normal daily serving, carefully recording all subjective and objective symptoms that might occur under provocation. Since false negative challenges do occur, for instance, due to degradation of the responsible allergens, an open food challenge always has to follow a negative blinded challenge.