A woman in her mid-forties called me in a panic. She was suddenly having hot flashes. She had never had hot flashes before nor had she had any other menopausal symptoms. In fact, she is still menstruating regularly. However, she was experiencing other symptoms –heart racing, weight loss, agitation, sleeplessness, increased body temperature– all pointing to hyperthyroidism, i.e., too much thyroid hormone. Since her thyroid tests and physical examination were both normal, her doctor wanted her to take estrogen for the hot flashes.
I recommended she do a simple test for iodine deficiency. This consists of “painting” a patch of Tincture of Iodine on the skin over the biceps. In her case the color of the Tincture of Iodine completely disappeared in less than two hours. This indicates a severe iodine deficiency. If there is no iodine deficiency the full color of the tincture will last at least 6 hours. I then recommended she take a tablet of protein-bound iodine per day. Within six days her hot flashes markedly decreased.
This case highlights several paradoxes of iodine deficiency.
A goiter often signals iodine deficiency. A goiter is an enlargement of the thyroid resulting from the thyroid gland’s attempt to concentrate iodine in itself. This woman had no thyroid enlargement.
Iodine deficiency is most commonly known to cause hypothyroidism, i.e., too little thyroid hormone. Hypothyroidism results in fatigue, weight gain, excessive sleeping, constipation, dry skin, mental sluggishness and decrease in body temperature. However, a more severe deficiency as seen here can indeed cause hyperthyroidism.
There is yet a fourth paradox of iodine. Excesses of iodine intake can cause both hypo- and hyperthyroidism.
How much iodine do we need? And, how much iodine do we get? An adult needs 150 micrograms (.15 milligrams) of iodine each day. A pregnant or lactating woman needs 200 micrograms. Many people consider iodized salt as the main source of dietary iodine for the US population. Iodination of salt began in 1922 in response to endemic goiter in the upper Midwest. The campaign to promote “voluntary” use of iodized salt did solve the endemic. However, iodine is not only added to salt. Other sources of iodine in the American food supply include use of iodine products in processing of dairy products and breads as well as supplementation of beef and chicken, resulting in variable amounts of iodine in meat, eggs and milk.
Here is the punchline. Although the prevalence of goiter declined to near zero, “Within 50 years the country had excessive iodine intake to the extent that other forms of thyroid problems, namely iodine-induced hypothyroidism, autoimmune thyroiditis, and hyperthyroidism, had become more common than deficiency disorders.” This conclusion is published in the 1998 Journal of Clinical Endocrinology and Metabolism in an article entitled “Iodine Nutrition in the United States.”
As the story continues to unfold, the above article, and an article, “Too Much Versus Too Little: The Implications of Current Iodine Intake in the United States,” published in Nutrition Review in 1999, both document a significant decline in iodine intake in the last twenty years, a decline in intake in all ages and both sexes. The highest incidence of deficiency of iodine is in women 40-49 years of age and secondly in women 30-60 years of age. Further, 6.7% of pregnant women and 14.9% of women of childbearing age have documented iodine deficiency, posing enormous risk of impaired neurological development to unborn children.