General text about the lack of minerals can be found here.
Iodine is a very important chemical element for our organism, because it is essential for proper production of thyroid hormones. These hormones are necessary for energetic metabolism and development of the body during childhood. Iodine is present in sea fish, in eggs and all plants growing in iodine-rich soil. However, due to iodine deficiency in some countries, iodization of salt is routinely performed to ensure adequate iodine intake for the whole population.
The main cause of iodine deficiency is its low dietary intake. The threat is higher in inhabitants of countries with a low intake of seafood. However, after the beginning of iodization, severe iodine deficiency is a very rare condition in civilized developed countries. Higher intake of iodine is needed in pregnant women for proper development of fetus.
The situation depends on whether the individual is exposed to iodine deficiency from birth or later in the life period. Insufficient intake of iodine in a fetus and newborn has permanent consequences and manifests with disrupted mental development and mental retardation. The condition is historically referred to as the cretinism. In addition to reduced IQ, the affected person suffers from lower growth, speech disorders and various motoric disorders. Once developed cretinism is incurable.
If an individual is exposed to iodine deficiency after his psychomotoric development has been completed, the symptoms are reversible. The person usually suffers from goiter (enlargement of thyroid gland), which occurs due to increased activity of the gland, which tries to utilize even the slightest amount of iodine taken into the body. In addition to goiter, the patient suffers from underactive thyroid gland (decreased production of thyroid hormones) manifesting with slower mental functions, depression, cold intolerance and fatigue.
The diagnosis is confirmed by clinical symptoms and decreased levels of thyroid hormones in serum. Theoretically, it is possible to indirectly determine the quantity of iodine in the body from the amount of iodine excreted in the urine, but this examination is not routinely performed.
It is necessary to increase dietary intake of iodine, but it is not always possible. Luckily, iodine may also be administered in dietary supplements. The recommended daily iodine intake in adult humans is estimated to be 150 micrograms, but in pregnant and lactating women, this amount should be increased over 250 micrograms a day.