The difference between hyperthyroidism and hypothyroidism lies in the clinical definition, etiology, and clinical manifestations. 1. Clinical definition: Hypothyroidism is a generalized low metabolic syndrome caused by hypothyroidism or thyroid hormone resistance due to various reasons. Hyperthyroidism is a clinical syndrome in which the thyroid gland itself produces too much thyroid hormone, leading to accelerated metabolic activity, increased excitability and hypermetabolism in the nervous, circulatory, digestive and other systems. 2. Causes: Hypothyroidism is mainly caused by insufficient levels of thyroid hormones in the body, and is usually associated with thyroid destruction, pituitary diseases, iodine deficiency, etc. Hyperthyroidism is mainly caused by insufficient levels of thyroid hormones in the body. Hyperthyroidism is mainly caused by the active function of the thyroid gland, which increases the level of its own synthesis and secretion of thyroid hormones, and is related to factors such as increased iodine intake and pituitary tumors. 3. Clinical manifestations: the clinical symptoms of patients with hypothyroidism are mainly characterized by reduced metabolic rate and decreased sympathetic excitability, and early patients with mild disease can have no specific symptoms. Hyperthyroidism patients often have agitation, irritability, tachycardia, fatigue, fear of heat, excessive sweating, weight loss, hyperphagia and other clinical manifestations. Hyperthyroidism or hypothyroidism is a disease, it is recommended to go to the hospital in a timely manner, in accordance with the doctor’s instructions for treatment, to avoid delaying the condition.