Clinically, iodine is an essential trace element for the human body. If iodine is deficient, it often causes iodine-deficiency related clinical diseases and causes corresponding clinical symptoms, mainly seen in the following cases: 1. Iodine deficiency: Patients who have insufficient iodine intake can cause iodine deficiency, which leads to macrosomia. Patients may show diffuse enlargement of the thyroid gland in the neck, which is generally not accompanied by abnormal thyroid function. Iodine salt supplementation should be given at this time to gradually restore the size of the thyroid gland to normal. 2. Thyroid autoimmune diseases: Patients with iodine deficiency can be at increased risk of thyroid autoimmune diseases, such as chronic lymphocytic thyroiditis, and patients can develop clinical manifestations related to neck swelling and neck swallowing difficulties. Severe patients may develop clinical symptoms of hypothyroidism, such as chills, fear of cold, bloating, constipation, weight gain, and hoarseness. In this case, it is necessary to improve thyroid function monitoring under the guidance of a physician and give levothyroxine tablets as replacement therapy if necessary.