Thyroid Dilemma
In my clinical practice, I have been perplexed by the recent rapid increase in patients presenting with both diagnosed and probable thyroid dysfunction (90% female). Just for a reality check, I went back to my old (1967) Robbins’ Pathology to see if he had anything to say about frequency of thyroid presentations: “Diseases of the thyroid, while not common in clinical practice, are nonetheless of great importance because most are amenable to medical or surgical management.” Robbins’ hopeful prognosis for thyroid case management might bring bitter responses from the millions of women who have experienced surgical or radiation ablation removal of their thyroids only to have many or most of their presenting symptoms and others return with a vengeance. The patient help phone lines at the Thyroid Foundation of America are flooded with thousands of calls from women wondering, “how come I feel awful again?” Currently, TFA endocrinologists are actively trying to improve this situation.
Worldwide, thyroid dysfunction is a probable risk factor for 1 to 1.5 billion people (WHO figures), usually considered due to simple iodine deficiency, presenting as goiter (at least 200 million), complex mental retardation from fetal and neonate iodine deficiency (iodine deficiency causes more mental retardation worldwide than all other causes combined), and physical deformities (at least 20 million). Low dietary iodine is also associated with increased rates and risk for breast, endometrial, and ovarian cancer; the cause is probably gonadotropin stimulation with a resulting hyperestrogenic state characterized by relatively high production of estrogen and estradiol.
However, the claim has been made for almost 80 years that North Americans are getting plenty of dietary iodine due to the ubiquitous use of iodized salt. Other sources of dietary iodine came from flour products and dairy products. Iodates were used as dough conditioners because they improve the cross-linking in gluten molecules and also act as mild antiseptics and mold retardants. In the dairy industry, iodine is used as disinfectant in teat dips in commercial machine-milking operations, with some iodine solution potentially dripping into the milk instead of large quantities of topical microbes. Stainless steel equipment is also washed with strong iodine solutions for sterilization. Despite these dietary sources of iodine, people still continue to get obvious low-iodine goiters, though the situation is much improved from the 1915-1919 years, for example, when the number one cause of recruit rejection for military service was overt goiter.
Rather than add more iodine to the diet, some endocrinologists have suggested that Americans are getting too much iodine and that increases in the incidence of autoimmune thyroid disease, namely Hashimoto’s hypothyroiditis and Graves’ disease (hyperthyroidism), parallel increased dietary iodine intake. Our high iodine intake, especially during the years 1940 to 1990, may be responsible for the high incidence of thyroid dysfunction currently presenting. The efforts to reduce dietary iodine have been overly effective, with recent surveys of food products and consumption indicating that the American diet may be borderline deficient in iodine intake, down from 500-800 ug in l980 to about 135 ug in 1995.
The North American thyroid dysfunction picture is, therefore, not simple. Rather than just simple iodine deficiency or excess, it is the thyroid gland itself that seems to be failing.
