Low thyroid hormone is generally indicative of possible hypothyroidism, but if it is simply low thyroid hormone, it cannot be used to confirm the diagnosis of hypothyroidism, and further tests are needed to clarify the diagnosis. In hypothyroidism, such as chronic thyroiditis, cretinism, iodine organic disorder, pituitary hypothyroidism and other diseases, there will be a decline in thyroid hormone levels, but such as thyroxine-binding globulin reduction, nephrotic syndrome and other diseases, thyroid function is normal can also be low thyroid hormone. In the case of hyperthyroidism, thyroid hormones are generally elevated. It is recommended to consult a doctor when low thyroid hormone occurs, combined with further examination to clarify the diagnosis and targeted treatment.