Whether the hypothyroidism is permanent can usually be determined by the cause of the hypothyroidism. If the hypothyroidism is after thyroidectomy, it is usually permanent and requires thyroid hormone supplementation. If the hypothyroidism is caused by subacute thyroiditis, it is usually curable because subacute thyroiditis is a self-limiting disease and will resolve on its own when it reaches a certain level. In addition, most of the hypothyroidism caused by medication can be recovered after stopping the medication. If the hypothyroidism is caused by autoimmune thyroiditis or thyroidectomy, it is usually difficult to be cured and is a permanent hypothyroidism, which requires lifelong treatment with levothyroxine sodium tablets to keep the thyroid hormone within a reasonable range. Patients diagnosed with hypothyroidism should actively cooperate with their doctors for treatment.