Doctor’s Tip: Risks, causes, treatment and prevention of hypothyroidism
The thyroid is a butterfly-shaped gland in front of the windpipe in your neck, that secretes thyroid hormone — which regulates your metabolism. The storage form of thyroid hormone is T4, which contains four iodine atoms. Once this is released into the blood, it is converted to the more active form called T3, which contains three iodine atoms.
Thyroid hormone production is regulated by TSH (thyroid stimulating hormone), which is secreted by the pituitary gland located at the base of your brain. If the thyroid is unable to produce enough thyroid hormone, the pituitary tries to rev it up by producing more TSH. The TSH level can be checked in the lab through a blood test. Normal ranges vary somewhat according to the lab, but in general are between 0.4 and 4.0. A TSH level higher than normal indicates hypothyroidism, while an abnormally low level indicates hyperthyroidism (an overactive thyroid gland).
For optimal health and vitality, it’s important that your TSH level remains in the normal range. Hypothyroidism, manifested by high TSH levels and low T4 levels, can cause the following: fatigue; sensitivity to cold; dry skin; constipation; weight gain; facial puffiness; hoarseness; weakness; aching; hair loss; depression; high cholesterol; slow pulse; and memory problems. Hypothyroidism in a pregnant woman results in lower IQ in the newborn, and if the hypothyroidism is severe, cretinism results, which is associated with multiple deficits including mental retardation.
The following factors can cause hypothyroidism:
• Worldwide, the most common cause is lack of iodine, which as noted above is an important component of thyroid hormone. Iodine is a naturally occurring element that occurs in varying amounts in soils throughout the world. Food grown in iodine-poor soils results in low iodine levels in humans who eat that food, resulting in hypothyroidism. In the United States and most other developed countries, iodine is added to most salt you buy at the grocery store in order to avoid iodine deficiency.
• In developed countries the most common cause of low thyroid is an autoimmune disease called Hashimoto’s thyroiditis, where a rogue immune system attacks the thyroid gland.
• Other causes of hypothyroidism include surgery or radiation for hyperthyroidism or for thyroid cancer.
• Rarely, low thyroid is caused by medications such as lithium.
To make an accurate diagnosis of low thyroid in a person with an elevated TSH, a T4 level should be drawn. Sometimes a blood test for thyroid antibodies is ordered as well, to check for Hashimoto’s disease. In classic hypothyroidism, the T4 level is low, and the treatment is straight-forward: daily levothyroxine (T4) pills, which should be taken first thing in the morning, at least 30 minutes before eating food or taking other medications including supplements. When the TSH is a few points above normal but the T4 is normal, treatment is controversial.
Once you start thyroid replacement, your TSH should be checked in around six weeks, and if needed your dose adjusted. Once your level is stable, it just needs to be checked once a year. Pregnant women need to increase their dose. If your hypothyroidism is treated and your TSH becomes normal, but you still have symptoms such as fatigue, doctors sometimes add T3 (triiodothyronine), to cover the possibility of inadequate conversion in your body of storage T4 to active T3.
Neal Barnard, M.D., is the founding president of Physician Committee for Responsible Medicine. He has authored several books, the latest, which came out in February, called “Your Body in Balance.” In the chapter on thyroid, he has the following “Menu for a Healthy Thyroid”:
• Iodine: not too much, not too little (both cause problems). There are many health reasons to avoid salt (sodium), but if you avoid iodized salt (keep in mind that sea salt, kosher salt and Himalayan salt are not iodized) you need to take an iodine supplement. The RDA of iodine for an adult is 150 mcg, 220 if pregnant, 290 if breast feeding. You can get your RDA by eating seaweed (sea vegetables) on a regular basis, and the RDA is present in many vitamin/mineral preparations or as a single iodine supplement. Avoid kelp due to too much iodine, and hijiki seaweed which can be contaminated with arsenic.
• Dr. Barnard also says to avoid animal products: “People who avoid meat, dairy products, and eggs have been shown in research studies to have the lowest risk of hypo- or hyperthyroidism,” probably because of lower rate of autoimmune disease in people on a plant-based diet. According to Dr. Barnard, when people switch from an animal-based to a plant-based diet, they often are able to cut back on their thyroid replacement dose, and sometimes their hypothyroidism resolves.
Greg Feinsinger, M.D. is a retired family physician who has a nonprofit: Prevention and Treatment of Disease Through Nutrition. He is available by appointment for free consultations (379-5718)
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