Iodine deficiency is a lack of iodine trace element, an important dietary nutrient. It can lead in a goiter, sometimes as an endemic goiter as well as cretinism owing to untreated congenital hypothyroidism, resulting in delays in development and other health issues.Low iodine concentrations are not the only reason for low thyroid function. But a shortage of iodine can trigger abnormal thyroid gland enlargement, known as goiter, and other thyroid issues. It may trigger mental illnesses in kids.