Do you have hypothyroidism? If so, you are not alone. Depending on the study you look at, hypothyroidism effects between 3% and 10% of the U.S. population. Hypothyroidism is a deficiency of thyroid hormones and is usually caused by under functioning of the thyroid gland. The disorder can cause symptoms of fatigue, weight gain, brain fog, constipation, cold intolerance, dry skin and hair, hair loss, and irregular menstrual cycles.
What is the Thyroid?
The thyroid is a small gland located in the front of neck and is a power house for the body. The thyroid gland produces our thyroid hormones, namely triiodothyronine (T3) and thyroxine (T4). T3 and T4 are synthesized from tyrosine, iodine, and various proteins. T3 is the most biologically active form of the hormone and receptors for T3 are located on cells all over the body. Thyroid hormones regulate the body’s metabolic functions, telling our cells how much energy to use, as well as controlling other hormonal systems.
The Thyroid and the HPA axis
Thyroid function is coordinated by two areas in the brain, the anterior pituitary and the hypothalamus. The pituitary gland and hypothalamus are two components of the hypothalamic–pituitary–adrenal (i.e. HPA) axis, which also includes the adrenal glands. The HPA axis is a complex relationship of hormones that control many functions in our bodies, including metabolism and reproductive functions.
The hypothalumus is responsible for producing thyrotropin-releasing hormone (TRH), which then stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). TSH stimulates the thyroid gland to produce thyroid hormones, T3 and T4. Normally, this process is a well-oiled machine with many efficient feedback loops, but there is the potential at any point for dysfunction to occur.
Causes of Hypothyroidism and Low Thyroid Function
Hypothyroidism is a medical term for low thyroid function. Hypothyroidism occurs when the thyroid gland does not produce enough T3 and T4 hormones. Most people with hypothyroidism will have elevated levels of TSH because the pituiatry gland will try to trigger the thyroid gland to function normally.
Hypothyroidism can have many causes. In developing countries, the most common cause of hypothyroidism is iodine deficiency. Iodine is a naturally occurring mineral found in many foods including seaweeds, milk and dairy products, fish and seafood, and eggs. The Recommended Daily Allowance (RDA) for iodine is 150 mcg for most adults, except for pregnant and breastfeeding women who should consume 200 mcg daily. In the United States and many other countries iodine intake is generally adequate because this nutrient is added to table salt. Therefore, in the U.S. the most common cause of a low functioning thyroid gland is Autoimmune Thyroiditis, also called Hashimoto’s Thyroiditis.
Hashimoto’s and Autoimmune Thyroiditis
Autoimmune diseases occur when the body creates autoantibodies and starts to attack its own tissues, organs, or glands. In Autoimmune Thyroiditis, antibodies may be produced to Thyroid Peroxidase (called Anti-TPO anitbodies) and/or Thyroglobulin (Anti-TG antibodies). Thyroglobulin is the primary protein component of thyroid hormones. Thyroid Peroxidase is an enzyme that helps iodine molecules attach to thyroglobulin in order to make the thyroid hormones T4 and T3. When the body cannot make enough thyroglobulin or thyroid peroxidase, hypothyroidism often occurs.
Unfortunately, we don’t know for sure what causes autoimmune diseases. There is often a genetic component, with some disorders being more common in families. There may also be environmental triggers such as toxic exposures, reactions to medications, or periods of prolonged stress. For most people, there is likely a combination of triggers along with a genetic predisposition that eventually tips the scales in favor of autoimmune reactions.
Treatments for Hypothyroidism
The typical treatment for Hypothyroidism is replacement of one or more of the thyroid hormones. Common medications include Levoythyroxine (containing only T4), USP Glandular Thyroid (containing both T3 and T4), or Liothyronine (only T3).
Selenium as a Treatment for Autoimmune Thyroiditis
Less is known about how to treat the autoimmune process that is taking place in Hashimoto’s, but a promising study published in the Society for Endocrinology shows that moderate supplementation with the nutrient selenium may decrease thyroid antibodies in Autoimmune Thyroiditis. The study showed the most benefit from taking daily selenium doses of 200mcg, which decreased levels of both Anti-TPO and Anti-TG antibodies.
Natural Sources of Selenium
Selenium is naturally found in many foods, although the levels generally reflect the amount of the mineral found in the soil where the food is grown. The best dietary source of selenium is Brazil nuts and eating 3 nuts per day gets you to approximately 200 mcg of selenium. Other sources of selenium include tuna, sardines, ham, shrimp and halibut, but the levels in these foods is much lower. For those with Autoimmune Thyroiditis, selenium may be an important supportive treatment to use in conjunction with thyroid hormone replacement therapies.
Resources
- Hypothyroidism: An Overview
- Hypothyroidism: Basics
- Selenium Dietary Fact Sheet
- Selenium Treatment in Autoimmune Thyroiditis: 9 Month Follow-Up with Variable Doses