Title:Role of Iodine in Metabolism
Volume: 10
Issue: 2
Author(s): Szybinski Zbigniew*
Affiliation:
- Department of Endocrinology, Jagiellonian University Collegium Medicum, 31-501 Krakow, 17 Kopernika St.,Poland
Keywords:
Iodine, iodine prophylaxis, thyroid hormones, metabolic pathway, synthesis, iodine deficiency.
Abstract: The natural resources of iodine are seawater, seaweeds and saltpeter-nitrate deposits in Chile.
Over 1/3 of the global population is exposed to iodine deficiency, especially in the mountains. Iodine is
a component of the thyroid hormones and a strong antioxidant with electric potential of -0.54 V. Iodine
as iodide is taken up by the thyroid gland, gastric mucosa, salivary glands and mammary glands in
pregnant and breast-feeding women. The transport of iodine to the thyroid gland is regulated by specific
enzymes: Natrium Iodine Symporter, Na+/K+ATPase, Pendrin and Apical Iodine Transporter. In the
thyrocytes, the thyroid hormones biosynthesis is carried out by iodization of tyrosine to T3 and T4. Secretion
of T3 and T4 is regulated by TSH. On the tissue level, the active hormones are T3 and its derivative
thyroamine. The most important target is the cardiac muscle, where T3 action results in an increase
in the inotropic action and thyroamines exert a negative inotropic and chronotropic effects. The consequences
of iodine deficiency are endemic goiter, irreversible brain damage, cretinism, impaired thyroid
function and thyroid, gastric and mammary glands cancers. In 1994, the World Health Organization
proposed the main strategy for iodine prophylaxis, i.e. Universal Salt Iodization. In Poland, a new model
of iodine prophylaxis was introduced in 1996; the model includes obligatory iodization of household
salt and neonate formulas and recommendation to take an additional daily dose of iodine for pregnant
and breast-feeding women. This model allowed for eliminating endemic goiter in schoolchildren, eradicating
cretinism in mountainous areas, and markedly diminished thyroid and gastric cancer incidence. In
2002, WHO classified Poland as a country with a proper daily iodine intake on the population level. No
relevant patents were reported for this WHO report.
