Low free thyroid hormone is caused by abnormal secretion of thyroid hormone in the body, which is usually the cause of hypothyroidism in the body. Low thyroxine often causes pallor, fatigue, and unresponsiveness, as well as anemia, facial edema, and edema of the lower extremities. In some cases, it may cause menstrual disorders, irregular menstruation, or difficulties in pregnancy. If you have low thyroid hormone, you should review your thyroid function regularly, and if the condition is serious, you should take medication. You may also need to pay more attention to your diet by eating foods rich in iodine, such as seaweed or seaweed.