Low thyrotropin may be associated with hyperthyroidism, subclinical hyperthyroidism, and Hashimoto’s thyroiditis. Thyrotropin levels in the blood are found to be lower than normal, and hyperthyroidism is usually considered if accompanied by symptoms of hyperthyroidism. It may also be subclinical hyperthyroidism, in which the patient’s clinical manifestations are not specific, but laboratory indicators have become abnormal. The synthesis and release of thyroxine in the body is controlled by the hypothalamus-pituitary-thyroid axis, and when the pituitary gland declines, it can also cause a decrease in thyrotropin. In addition, reduced thyrotropin levels may also occur in some diseases, such as Hashimoto’s thyroiditis when there is destruction of the thyroid gland releasing too much thyroid hormone and suppressing thyrotropin. Low thyroid stimulating hormone can also be caused by other reasons, it is recommended to follow the doctor’s instructions to improve the relevant examination, with the help of the doctor to clarify the cause, and targeted treatment or therapy.