Thyroid peroxidase antibody should refer to anti-thyroid peroxidase antibody, and its index of 900IU/mL is more than whether it is serious or not, need to be combined with other thyroid function test index. If it is combined with Graves’ disease, it is usually not serious after active treatment as prescribed by the doctor. Elevated anti-thyroid peroxidase antibody can be seen in chronic lymphatic thyroiditis, systemic lupus erythematosus and other diseases, which need attention. 1. Chronic lymphoid thyroiditis: It is a chronic autoimmune inflammatory disease of the thyroid gland, which may show symptoms such as neck swelling and hypothyroidism. Antithyroid peroxidase antibody and thyroglobulin antibody may be positive. 2. Systemic lupus erythematosus (SLE): It is a connective tissue disease that involves multiple systems and is clinically characterized by symptoms such as butterfly-shaped erythema on the face. Elevated thyroid peroxidase antibodies may also be present. The normal range of anti-thyroid peroxidase antibody is <60IU/ml, and when it rises to 900IU/mL, you should go to the hospital in time, complete the relevant examinations to clarify the cause of the disease, and treat the symptoms under the guidance of the doctor.