High immunoglobulin E indicates the possibility of allergic diseases, parasitic infections, rheumatoid arthritis or hematologic diseases. 1. Allergic diseases. Allergic rhinitis, chronic urticaria or exogenous asthma may cause high immunoglobulin E. 2. Parasitic infections. Patients with parasitic infections may also have high immunoglobulin E levels. 3. Rheumatoid arthritis. Rheumatoid arthritis or eczema may cause high immunoglobulin E in some patients. 4. Hematologic diseases. Immunoglobulin E may also be high in multiple myeloma type IgE. Immunoglobulin E is mainly related to allergic reactions. Patients with allergies or hypersensitivity may usually have high immunoglobulin E in their serum, which is important for the diagnosis of many allergic diseases.