There are several reasons for high thyroid hormone levels: The first reason is that thyroid hormone levels are the most sensitive indicator of thyroid function, and when thyroid function decreases at a very early stage, free thyroid hormone levels have not decreased, but thyroid hormone levels are already high. Therefore, in the early stages of primary hypothyroidism or chronic Hashimoto’s thyroiditis, thyroid hormone levels can be high, but free thyroxine levels are normal. The second reason, most often seen in women during pregnancy, is that the body’s demand for thyroid hormones increases significantly after pregnancy, and there may be a high level of thyroid stimulating hormone while the free thyroid hormone level is within the normal range. If thyrotropin levels are high during pregnancy, oral euthyroid replacement therapy may be required depending on the actual situation. Adults with high thyroid stimulating hormone levels not exceeding 10 mU/L do not require oral replacement therapy with eugenol, and regular review of thyroid function is sufficient.