Iodine is a trace element which appears to have several roles in the human body. First, it is necessary for proper development of the nervous system, and secondly, it maintains the proper function of the endocrine system. This element may also enable the immune system to operate and therefore have a beneficial effect on the body when certain diseases are present.
Iodine and body function
Iodine absorbs very well through the gastrointestinal tract, and after it enters the circulation, the element sequesters in the thyroid gland. This happens because iodine is necessary for the body to make thyroid hormone. Specifically, it makes thyroxine and triiodothyronine. The thyroid gland produces thyroxine which regulates the body metabolism and other important activities.
The pituitary gland secretes thyroid stimulating hormone to effect the operation of the thyroid gland. If there is insufficient iodine available in the body, the pituitary gland releases large amounts of thyroid stimulating hormone into the bloodstream to address the situation. Conversely, when the thyroid gland secretes too much thyroxine, the pituitary gland receives feedback to decrease the amount of thyroid stimulating hormone that it will release.
The occurrence of iodine deficiency may cause the thyroid gland to become enlarged, and the medical term for this condition is goiter. Since any iodine which the thyroid gland does not use exits the body via the urine, it is possible to perform a urine test to determine whether an individual has sufficient iodine in his or her body.
As iodine deficiency causes an unusually large release of thyroid stimulating hormone, blood tests will indicate in a patient with underactive thyroid gland that the level of thyroid stimulating hormone is too high. And in those with an overactive thyroid gland, the blood level of thyroxine will rise above the limits of normal.
Mild to moderate iodine deficiency in adults may lead to goiter, and there may be a decrease in productivity at work or impairment in mental function. If the deficiency of this nutrient continues for a long time, the patient is at risk for the development of thyroid cancer.
Although a well-balanced diet will probably prevent the occurrence of iodine deficiency, particularly in regions of the world where salt iodization is available, there are certain foods which may interfere with the availability of iodine in the human body. These foods, or goitrogens, include cabbage, cassava, broccoli, cauliflower, and other cruciferous vegetables. Goitrogens interfere with the uptake of iodine in the thyroid gland and tend to worsen a case of iodine deficiency.
The tissue of a woman’s breast contains considerable amounts of iodine especially during pregnancy or breastfeeding. Some studies suggest that iodine supplementation is beneficial for patients who have fibrocystic disease of the breast.
Radiation emergencies have taken place in which there is an accidental release of radioactive iodine into the environment. People who have encountered radiation exposure by these events will be at risk for cancer of the thyroid gland. However, treatment of these patients with potassium iodide will significantly reduce the possibility of thyroid cancer development.
Excessive iodine intake
Excessive intake of iodine may lead to serious medical conditions. These patients tend to develop hyperthyroidism, or overactivity of the thyroid gland, or hypothyroidism which is underactivity of the gland. The thyroid gland may develop an inflammatory condition that can lead to cancer. If a patient takes an overdose of several grams of iodine, there will be acute iodine poisoning, but this is a rare medical condition.
It is important that patients who take iodine or any other vitamin and mineral supplement always tell their physician because there may be drug interactions. For instance, agents to treat high blood pressure such as lisinopril, fosinopril, and benazepril can interact with iodine. The use of potassium iodide can elevate the level of potassium in the blood when patients take those same medications for blood pressure.
Some blood pressure medications include an agent to prevent the patient from elimination of potassium through the urine, and if they also take potassium iodide, the blood level of potassium may become dangerously high. Elevation of the potassium in the bloodstream can predispose to fatal rhythm disturbances of the heart.
Finally, potassium iodide has the potential to interact with medications which are for the treatment of thyroid gland overactivity.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
References
Maria Andersson, Bruno de Benoist, and Lisa Rogers. “Epidemiology of iodine deficiency: Salt iodisation and iodine status.” Best Practice and Research Clinical Endocrinology and Metabolism 24 (2010): 1-11.
National Institutes of Health. Office of Dietary Supplements. (2010). Dietary supplement fact sheet: Iodine. Retrieved February 10, 2011.
Michael Koger - Dr. Koger obtained his medical education at Meharry Medical College and specialized in Internal Medicine.
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