Hyperthyroidism can cause low menstrual flow. It can involve several systems, including the endocrine system. In women, it often manifests as decreased menstrual flow, prolonged cycles, or even amenorrhea, and in men, it can cause symptoms such as breast development and impotence. In addition to the endocrine system, multiple systems can also be involved. In addition, patients with hyperthyroidism mainly present with hypermetabolic syndrome, including fear of heat, excessive sweating, fatigue, warm skin, dampness, hypothermia, and weight loss, and with neurological involvement, insomnia, nervousness, anxiety, irritability, inattention, and irritability. If the cardiovascular system is involved, palpitations and shortness of breath may occur, which may increase after activity. Involvement of the digestive system often manifests as hyperphagia, increased frequency of stools, or diarrhea.