The thyroid gland is the largest endocrine gland in the body and is located on both sides of the trachea in the neck. It takes in iodine, synthesizes thyroxine, and plays a regulatory role in the physiological functions and metabolic activities of the body. Hyperthyroidism is a condition caused by the overproduction of thyroxine. It occurs slowly or rapidly, with the thyroid gland gradually enlarging within weeks to months. In general, patients often have symptoms such as low fever, panic attacks, fatigue, excessive food and hunger, irritability, weight loss, easy sweating, protruding eyes, and increased stool frequency. As the thyroid gland in the elderly gradually shrinks with age, its function also decreases. After suffering from hyperthyroidism, although the secretion of thyroxine increases, the binding power of thyroxine in the blood decreases and the body’s ability to respond to thyroxine is weakened. Therefore, the clinical manifestations of hyperthyroidism in the elderly differ from those of young patients. Usually, the above-mentioned symptoms, such as hyperphagia, nervousness and excitement, and obvious enlargement of the thyroid gland, are not obvious and are often overlooked and easily misdiagnosed. Generally speaking, hyperthyroidism in the elderly usually has the following three clinical features: 1. Under the action of large amount of thyroid hormones, the burden on the heart increases, leading to deterioration of the condition. Atrial tachycardia, atrial fibrillation, tachycardia, angina pectoris, increased myocardial ischemia or even heart failure can occur. According to statistics, about 1/3 of hyperthyroid patients over 40 years old have hyperthyroidism and 5% have atrial fibrillation. Usually, patients only pay attention to the symptoms of heart, but ignore the existence of “hyperthyroidism” and delay the treatment. 2, the main performance of the digestive system: patients usually feel loss of appetite, poor appetite, anorexia or alternating diarrhea and constipation. It is believed that this is related to the chronic and lack of gastric acid that is often combined with the elderly. Due to less eating and more consumption, there is usually a significant weight loss, some patients can lose 10-20 kg in a short period of time, and are often suspected of having malignant tumors. 3.Mainly mental symptoms: Patients mostly show indifference, unresponsiveness, depression, drowsiness, few words, indifference in dealing with others and so on. This condition is called covert or indifferent hyperthyroidism, and is almost exclusively seen in elderly hyperthyroid patients of advanced age. These patients are prone to thyroid crisis and should be especially alert. Therefore, when elderly people experience tachycardia, atrial fibrillation, rapid weight loss, extreme anorexia or depression, it is important to think about the possibility of hyperthyroidism and go to the hospital for thyroid function tests as soon as possible.