Antithyroid peroxidase antibodies greater than 1000 IU/ml do not represent the severity of the disease, but are significantly elevated and require further testing. Antithyroid peroxidase antibody is one of the autoantibodies of the thyroid tissue. The more elevated the anti-thyroid peroxidase antibodies, the greater the likelihood that the patient will develop hypothyroidism. Antibodies to thyroid peroxidase are cytotoxic and bind to the enzyme thyroid peroxidase, inhibiting the enzyme’s activity and wreaking havoc on thyroid function. For example, if the inflammation of the thyroid gland is active and the antibodies to thyroid peroxidase are less than 1,000 IU/ml, it means that the patient’s condition is severe. In addition, hyper- or hypothyroidism results in high antibodies without effects on the brain, heart and systemic systems or other complications. Thyroid function is normal at the time of examination, and this condition is not considered serious. Thyroid function and thyroid ultrasound can be rechecked regularly. To summarize, whether the patient’s condition is serious or not needs to be judged according to the changes in the level of thyroid function and the changes of the disease on the body.