This document discusses iodine deficiency disorders of the thyroid gland. It describes how low iodine intake can lead to goiter formation as the thyroid attempts to maintain normal thyroid hormone levels. It classifies goiter sizes and discusses the epidemiology of endemic goiter. It also describes how iodine deficiency can cause cretinism and outlines methods for diagnosing iodine deficiency disorders. The document concludes by discussing prevention through iodine supplementation and treatment by ensuring adequate iodine intake through foods like iodized salt.