IgE refers to immunoglobulin E in plasma. Immunoglobulin E is a type of immunoglobulin in human plasma. Immunoglobulins commonly used in clinical practice include IgA, IgG, IgM, IgD, and IgE. Elevated immunoglobulin E is often seen in patients with urticaria, allergic rhinitis, bronchial asthma, etc. Elevated immunoglobulin E may also occur when Mycobacterium tuberculosis infects the human body. Patients with elevated immunoglobulins due to the above etiologies often show mild elevations without significant decreases in other immunoglobulins. The elevation of immunoglobulin E in these patients is temporary and may gradually return to normal after the primary disease is cured. Hematologic malignancies, such as multiple myeloma and Hutchinson’s macroglobulinemia, can also lead to elevated immunoglobulin E, which is often markedly elevated and accompanied by a decrease in other immunoglobulins. If patients have abnormal immunoglobulin E, they should consult the hematology department in time to identify the specific cause of the disease and then treat the cause of the disease.