When the thyroid ultrasound is normal, a thyroid function test is generally not necessary. Only in the following two cases is a thyroid function test necessary: First, if there are symptoms of dry mouth, excessive drinking, polyphagia, polyuria and weight loss, accompanied by symptoms of irritability, irritability, fear of heat, excessive sweating, panic, hand trembling and protruding eyes, then a thyroid function test can be performed to exclude hyperthyroidism. Secondly, if there is chilliness, cold limbs, swollen limbs, constipation, dull yellow skin and ginger palms, thyroid function test can be performed to exclude hypothyroidism.