Whether or not thyroglobulin antibodies of 300 IU/ml are serious needs to be analyzed depending on the cause. The normal value is <60IU/ml, and 300IU/ml is relatively high. Thyroglobulin antibodies belong to the autoimmune antibodies of the thyroid gland. Among the autoimmune diseases of the thyroid gland, elevated thyroglobulin antibodies are more common, which are commonly found in autoimmune diseases of the thyroid gland, such as Hashimoto's disease, Graves' disease and so on. After receiving regular treatment, the condition of these patients can be better controlled. In addition, thyroglobulin antibody 300IU/ml may also be due to thyroid follicular carcinoma, papillary thyroid carcinoma, etc., which often needs to be diagnosed by fine-needle aspiration biopsy or histopathological examination. For patients with thyroid cancer, prompt surgical treatment is recommended. If left untreated, it may lead to tumor metastasis, which can be life-threatening in severe cases. If thyroglobulin antibody 300IU/ml is detected, it is necessary to consult a professional doctor in time.