Iodine is essential for the thyroid gland to produce its hormone, thyroxine. People lacking thyroxine become sluggish, mentally and physically. An infant suffering from a shortage of thyroxine is called a cretin. Cretinism (congenital hypothyroidism) can cause stunted growth, severe mental impairment, deafness or even deaf-mutism, and paralysis.
In adults one of the first signs of iodine deficiency is a swelling in the neck of the thyroid gland (goitre).
Iodine occurs naturally in seafoods and can be artificially added to food products. Cases here are all due to iodine deficiency in the diet. Other causes for a failure to be able to produce thyroxine hormone are included within endocrine disorders, Map 437.
Iodine deficiency caused 0.011% of all deaths worldwide in 2002, an average of 1 death per million people per year.