Histamine Intolerance: Clinical Characterization and Determination of Serum Diamine Oxidase (Dao) in a Series of Cases and Controls

Abstract

Introduction. Histamine intolerance (HIT) is a pathology with an estimated prevalence of 1% in which there is an imbalance between the intake of histamine via the digestive tract and the body's ability to degrade it. This results in an excessive accumulation of histamine that determines the appearance of gastrointestinal, skin, respiratory and neurological symptoms. The enzyme responsible for degrading histamine in the extracellular space is diamine oxidase (DAO); therefore, HIT is caused due to a deficit in the concentration and/or in the activity of this enzyme. Because histamine is the main mediator of the classic symptoms of IgE-mediated allergic reactions, it is difficult to differentiate a true allergy from HIT since it has basically the same clinical manifestations. Objectives. The objective of this study was to perform a clinical characterization of patients with HIT and to determine the usefulness of quantifying serum DAO concentration in the diagnosis of HIT. Method: Twenty-two patients over the age of 18 with a history of histamine intolerance were recruited, in whom IgE-mediated food allergy was ruled out, and 22 healthy patients. Both groups were surveyed and serum DAO concentration was determined. Results: Middle-aged women predominated in the population with HIT. They described a wide variety of symptoms, with a dominance of abdominal pain, bloating, diarrhea, flushing, urticaria, itching, headache and dysmenorrhea. When comparing the average serum DAO concentration in the population with HIT (10.686 U/ml) with the average obtained in the control population (20.664 U/ml), there was a significant difference (p < 0.003). Conclusion. The determination of serum DAO concentration is a useful tool for the diagnosis of HIT.