The danger of high urinary iodine is determined by the patient’s specific situation. If the urinary iodine level is high due to the recent intake of iodine ions, this is normal and the patient should not be overly concerned. In other cases, it may be caused by thyroid-related diseases, which increase the iodine level in the blood, and the reabsorption function of the kidneys absorbs the iodine ions in the blood into the urine, thus causing high urinary iodine. This is the danger that is caused by thyroid disease, so it is important to treat thyroid disease in a timely manner.