Urine test is to check the level of alkali content in urine, which is mainly used to check thyroid function. This urine test is less used clinically, or in many hospitals, urine is basically not used to check iodine and thyroid function. At the same time, the iodine secreted by the human body fluctuates greatly in urine, and the amount of excreted iodine varies greatly from time to time and under different physical conditions, and is unstable. Therefore, it is not reliable to check thyroid function by checking iodine in urine. For patients who suspect thyroid abnormalities, a blood test for thyroid function is the most common and reliable way to check thyroid disease and thyroid function.