Thyroid hormones are not proteins. Thyroid hormone belongs to the amino acid class of hormones, which is synthesized from tyrosine iodination in thyroid cells, and is influenced by the pituitary gland to regulate the metabolic balance of many substances in the body. If there is an imbalance in the secretion of thyroid hormone and a deficiency occurs, symptoms of hypothyroidism will appear, including bradycardia, weight gain, fear of cold, and mucous edema; if there is an overproduction of thyroid hormone, it is called hyperthyroidism, which manifests itself as palpitations, tremors of the hands, excessive sweating, fear of heat, excitability, irritability, insomnia, headache, vomiting, weight loss, and disorders of the menstrual cycle. It is recommended that when thyroid hormone secretion is abnormal, consult a doctor promptly and follow the doctor’s instructions for appropriate treatment.