Diagnosis Exclusion of other causes Diagnosis of idiopathic environmental intolerance initially involves exclusion of known disorders with similar manifestations: Allergies (eg, allergic rhinitis, food allergies) Atopic disorders (eg, asthma, angioedema) Building-related illnesses Endocrine disorders (eg, carcinoid syndrome, pheochromocytoma, mastocytosis) Atopic disorders are excluded based on a typical clinical history, skin-prick testing, serum assays of specific IgE, or all 3.