The severity of the disease cannot be judged only from the fact that immunoglobulin E is higher than the upper limit of the normal reference value by 400IU/ml, but rather, a comprehensive analysis should be made from the causes of the elevated immunoglobulin E as well as the personal factors, etc. Elevated immunoglobulin E is mainly seen in allergic diseases, parasitic infections and autoimmune diseases. Immunoglobulin is a protein mainly involved in various types of immune reactions, among which immunoglobulin E has a high affinity for mast cells and basophils, under normal circumstances below 100IU/ml, higher than the upper limit of the normal reference range of 400IU/ml is an abnormal result, which can be seen in chronic urticaria, allergic rhinitis, exogenous asthma and other allergic diseases. In addition to allergic diseases, patients with parasitic infections, drug-induced interstitial pneumonitis, bronchopulmonary aspergillosis, rheumatoid arthritis, lgE myeloma, and acute and chronic hepatitis can also have elevated immunoglobulin E. Therefore, patients should further improve autoantibodies, liver and kidney functions, blood routine and other related auxiliary examinations to clarify the cause. The severity of immunoglobulin E elevation caused by different diseases varies greatly, so it is recommended that patients go to the rheumatology and immunology department, dermatology department and infection department of regular hospitals for detailed consultation.