Hypothyroidism is short for hypothyroidism and hyperthyroidism refers to hyperthyroidism. Hypothyroidism may become hyperthyroidism under certain circumstances, such as medicated hyperthyroidism. Hypothyroidism may lead to pharmacologic hyperthyroidism if the amount of thyroid hormone replacement is high during treatment and is not regularly reviewed. Therefore, hypothyroidism in the process of taking medication, once palpitations, fear of heat, excessive sweating, irritability and other symptoms, should promptly check the thyroid function to avoid the emergence of pharmacological hyperthyroidism. Hypothyroidism in the treatment, the need for regular review, according to the function of the thyroid gland to adjust the dosage of levothyroxine, to avoid adverse consequences.