Thyroid peroxidase antibody 1300 is not serious if the thyroid function is normal, and regular review is sufficient. Thyroid peroxidase can promote the addition reaction between iodine ions and tyrosine residues of thyroglobulin, which catalyzes the production of thyroid hormone. Elevated thyroid peroxidase antibody suggests autoimmune thyroiditis. If the thyroid function is normal, it is not serious, and regular rechecking of the thyroid function is sufficient. If goiter and hypothyroidism (e.g., malaise, chills, and slow heart rate) are present, thyroid hormone replacement therapy is needed to maintain normal thyroid function, which is also not too serious. Thyroid peroxidase antibodies of 1300+ should be seen promptly and treated under a doctor’s supervision.