Hypothyroidism is a condition in which the thyroid gland fails to function adequately, resulting in reduced levels of thyroid hormone in the body. Cretinism is a type of hypothyroidism that occurs at birth and results in both stunted physical growth and mental development. Severe hypothyroidism is called myxedema.
There are many causes of hypothyroidism. Hashimoto’s thyroiditis, an autoimmune disease of the thyroid gland, may lead to hypothyroidism. Some medical treatments, such as surgery or radiation to the thyroid gland, or certain drugs like lithium and phenylbutazone, may also induce this condition. Extreme iodine deficiency, which is rare in the United States, is another possible cause. Failure of the pituitary gland or hypothalamus to stimulate the thyroid gland properly can cause a condition known as secondary hypothyroidism.
Some people with goiter (an enlargement of the thyroid gland) also have hypothyroidism. Goiter can be caused by iodine deficiency, by eating foods that contain goitrogens (goiter-causing substances), or by other disorders that interfere with thyroid hormone production. In many cases the cause of goiter cannot be determined. While natural therapies may help to some extent, thyroid hormone replacement is necessary for most people with hypothyroidism.
Dietary changes that may be helpful: Some foods, such as rapeseed (used to make canola oil) and Brassica vegetables (cabbage, Brussels sprouts, broccoli, and cauliflower), contain natural goitrogens that appear to act by interfering with thyroid hormone synthesis. Cooking has been reported to inactivate this effect in Brussels sprouts.Cassava, a starchy root that is the source of tapioca, has also been identified as a goitrogenic food. Other goitrogens include maize, sweet potatoes, lima beans, and pearl millet.
Lifestyle changes that may be helpful: Preliminary studies have found an association between multiple chemical sensitivities and hypothyroidism. One study found a correlation between high blood levels of lead, a toxic substance, and low thyroid hormone levels in people working in a brass foundry. Of the 47 workers tested, 12 were considered hypothyroid; many of these individuals also complained of depression, fatigue, constipation, and poor memory (symptoms of hypothyroidism).
What is of great concern is not clinically evident hypothyroidism that is clearly testable and reasonably understood. It is sub-clinical hypothyroidism which is harder to detect and far more prevalent. Subclinical hypothyroidism can be detected or identified in the following ways:
1) Barnes Test: Measuring your temperature when rising in the morning on a daily basis.
If your temperature is consistently one degree centigrade or less, suspect your thyroid is under the weather.
2) Iodine patch test: Paint an iodine patch on your skin and watch to see how long it takes to disappear. If your thyroid is functioning well the patch will take more than 24 hours to disappear.
3) Blood Tests: Most physicians measure only T4 and TSH. However, T3 is a more sensitive marker for subclinical thyroid function. The T3 reading is often in the lower third range or clinically in the low range. Alternatively you can do both a T3 and reverse T3 test. In the presence of subclinical hypothyroidism, the reverse T3 will be high and T3 will be low.
Occupational exposure to polybrominated biphenyls and carbon disulfide has also been associated with decreased thyroid function. Nutritional supplements that may be helpful: The relationship between iodine and thyroid function is complex. Iodine is required by the body to form thyroid hormones, and iodine deficiency can lead to goiter and hypothyroidism.
Sources of iodine include foods (iodized salt, milk, water, seaweed, ground beef), dietary supplements (multiple vitamin/mineral formulas, seaweed extracts), drugs (potassium iodide, amiodarone, topical antiseptics), and iodine-containing solutions used in certain laboratory tests. Many nutritional supplements contain 150 mcg of iodine. While that amount of iodine should prevent a deficiency, it is not clear whether supplementing with iodine is necessary or desirable for most individuals. People wishing to take a nutritional supplement containing iodine should consult a doctor. Experimental animals with severe zinc deficiency developed hypothyroidism, whereas moderate zinc deficiency did not affect thyroid function.
Selenium also plays a role in thyroid hormone metabolism. Recently, severe selenium deficiency has also been implicated as a possible cause of goiter. In one study, it was reported that giving 50 mcg of selenium per day to people who were deficient in both selenium and iodine decreased thyroid function in those who were already hypothyroid. Other researchers have suggested that selenium should not be given to people who are deficient in both selenium and iodine, without first giving them iodine or thyroid hormone supplementation. There is no research demonstrating that selenium supplementation helps people with hypothyroidism who are not selenium-deficient.
Desiccated thyroid, also called thyroid extract, is used by some doctors as an alternative to synthetic thyroid hormones (such as thyroxine and levothyroxine) for people with hypothyroidism. Thyroid extract contains two biologically active hormones (thyroxine and triiodothyronine), whereas the most commonly prescribed thyroid-hormone preparations contain only thyroxine. One study has shown that the combination of the two hormones contained in desiccated thyroid is more effective than thyroxine alone for individuals with hypothyroidism. One doctor reported that in his experience, thyroid extract works better than standard thyroid preparations for some people with hypothyroidism.Glandular thyroid products, which are available from health food stores, have had most of the thyroid hormone removed and would therefore not be expected to be effective for individuals with hypothyroidism. Intact desiccated thyroid is available only by prescription. People with hypothyroidism who want to use desiccated thyroid must first consult with a physician.