The t4 is the total thyroid hormone. If only the total thyroid hormone is high after pregnancy, and the thyrotropin and t3 are normal, it is a normal phenomenon during pregnancy. However, if there is a significant increase in t4, accompanied by a decrease in thyrotropin or a significant increase in t3, it should be suspected that the pregnancy is combined with hyperthyroidism. During pregnancy, the thyroid gland is in a relatively active state, resulting in an increase in serum total thyroxine and t3, but this increase is mild, so pregnancy is found to have only high total thyroid hormone, but all other normal, usually belongs to the normal phenomenon during pregnancy. Serum total thyroxine elevation is obvious, the patient at the same time accompanied by a decline in thyrotropin, t3 increase, this situation should be suspected of pregnancy hyperthyroidism, need to go to the hospital for diagnosis and treatment, in order to avoid affecting the fetus.