One is to avoid iodine diet, not to eat seafood and food with high iodine content. Another is to stop taking anti-thyroid medication for at least two weeks before having the iodine rate test. The iodine uptake rate test is performed by measuring the intensity of radioactivity directly in the thyroid gland after oral administration or injection of a small amount of iodine-containing elements. If the iodine uptake rate increases or if the peak is shifted forward, consider primary hyperthyroidism; if the iodine uptake rate is significantly lower, consider thyroiditis or hypothyroidism.