Total IgE examines the amount of IgE in the serum, and abnormalities can indicate allergic reactions and diseases of the immune system. IgE is an antibody that mediates type I allergic reactions and is associated with allergic reactions, allergies and parasitic infections. IgE levels in umbilical cord blood of infants are very low and gradually increase after birth, reaching adult levels by the age of 12 years. Elevated IgE is seen in heavy chain disease, multiple myeloma with IgE type, rheumatoid arthritis, allergic asthma, allergic rhinitis, urticaria, eosinophilia, and parasitic infections. Decreased IgE can be seen in congenital or acquired gammaglobulin deficiency, malignant tumors, and long-term use of immunosuppressive drugs for treatment of diseases. The total IgE test is a common test to determine the body’s allergy.