IODINE REQUIREMENT AND GOITRE

Iodine is one of the halogens. It is one of the essential micronutrients needed by humans. The body contains 20-50mg of iodine and is an essential component of the secretions of the thyroid gland. The thyroid gland synthesizes, stores and secretes the thyroid hormones thyroxine,T4 and tri-iodothyronine,T3. The rate of synthesis and secretion of thyroid hormones are controlled by the pituitary gland. Thyroxine (T4) and tri-iodothyronine (T3) regulate oxygen consumption and heat production including a wide range of metabolic processes. They are also essential for normal growth and development. Iodine after peroxidation, becomes attached to tyrosine residues of thyroglobulin.




Food sources rich in iodine include sea foods such as crayfish, oyster, prawn, lobster and crabs, seeds, eggs, dairy products, cereals. Consumption of iodine is highly variable in different parts of the World.
The minimum requirement for adults has been estimated at 50-75µg/day. Children and mothers require more. Studies have shown that people who live in mountainous regions suffer from iodine deficiency because the soil contain little quantity of iodine. Hence, local produce have little iodine content .Such people suffer from endemic goiter. Endemic goitre results from low levels of thyroid hormones. Endemic goitre is characterized by enlarged thyroid gland.




The development of iodine deficiency can be averted through these methods viz; the addition of potassium iodate to salt used in cooking or in bread (i.e food fortification).In long standing goitre, the use of tyrosine treatment (9.3µg/day) yields appreciable results. Foods rich in gutrogens should be avoided. Examples of such foods are turnips and cabbages.





Iodine toxicity results when doses exceeding the normal daily requirement are administered. The addition of potassium iodate to food for the prophylaxis to endemic goitre is not devoid of hazards if overdose are added. In studies involving animal models, excessive amounts have been shown to inhibit thyroid hormone synthesis. Thyroid necrosis has also been reported.