The diagnostic indicators of hypothyroidism are mainly based on the levels of thyroid stimulating hormone, free thyroid hormone and free triiodogen thyroid hormone. For ordinary people, if the level of thyroid stimulating hormone is less than 10mIU/L, and the level of free thyroid hormone and free triiodothyronine thyroid hormone is within the normal range, drug treatment can be temporarily abandoned. When the thyroid stimulating hormone level is greater than 10mIU/L, and the free thyroid hormone and free triiodothyronine thyroid hormone levels are in the normal range, it is considered to be subclinical hypothyroidism. If there is abnormal blood lipid or atherosclerosis, it can be treated with levothyroxine sodium tablets to maintain thyroid function in a reasonable range. When the patient has a clear clinical hypothyroidism, that is, the level of thyroid stimulating hormone increases, and the level of free thyroid hormone and triiodothyronine thyroid hormone decreases, in consideration of clinical hypothyroidism, it is necessary to give levothyroxine sodium tablets in time for treatment.