Guide

Outside of the US, it is iodine deficiency which is one of the most common causes of hypothyroidism. Iodine must be supplied by the diet. It is an essential component of thyroid hormone. Iodine though should be available in normal diet, often it is lacking. A fairly common way to augment iodine requirement of the body is by using iodised salt.

In the US, Hashimoto's disease is the most common cause of hypothyroidism. Hashimoto's disease, named after the Japanese doctor who first described it, is an autoimmune condition in which the body's immune system attacks and destroys the thyroid gland.