So why do we need iodine. What is it actually do? Well iodine is a key constituent of the thyroid hormones that are crucial to growth and metabolism under absolutely essential for brain development especially of the baby in the womb. Iodine deficiency is the largest preventable cause of learning disabilities in the world. If pregnant women do not get enough iodine, their children can be born with a learning disability or in extreme cases with congenital thyroid hormone deficiency historically known as cretinism. Another result of iodine deficiency is a goitre, a swelling of the thyroid gland in the neck as it tries to track more iodine from the blood stream. Goitre can become really massive an extreme deficiency. Thyroid gland is related to metabolic rates in your control of cells energy and involved in almost all body processes and so they're really sort of three groups of problems that can occur in Thyroid disease. One is that your thyroid gland can under perform that's called hyperthyroidism. One is that you can make to much hormone that's called hypothyroidism with our tools cases.