Understanding Thyroid Hormones
It is estimated that 20 million Americans have some type of thyroid disorder. Women are five to eight times more likely to develop a thyroid condition than men, and as many as 60 percent of people with thyroid disease are unaware they have it.
Hypothyroidism is a condition where the thyroid gland doesn’t produce enough thyroid hormone. With one of its main functions being to regulate metabolism, low levels of the thyroid hormone can lead to a number of symptoms, including fatigue, depression, brain fog and weight gain. Although hypothyroidism can develop at any time, it is more common during middle age. The most common condition that causes hypothyroidism is Hashimoto’s thyroiditis, an autoimmune disorder where the body’s own immune system attacks thyroid cells. The onset of this condition usually occurs between the ages of 30 and 50.
Although there are many concerns associated with hypothyroidism, there are several reasons why someone with a thyroid condition might not be properly diagnosed. Most conventional doctors only test blood1 for three hormones. The first, TSH, is a signaling hormone that tells the thyroid to produce more thyroid hormone. Total T4 and Free-T4 are types of thyroid hormones. Unfortunately, these tests don’t show enough of the bigger picture of what’s actually happening in your body. It is important to also test the thyroid hormone’s active form, Free-T3, and its inactive form, Reverse-T3.
The Significance of Free-T3 and Reverse-T3
The active form of thyroid hormone is T3, which is used within every cell in your body to regulate your metabolism. The majority of thyroid hormone being made in the thyroid itself is T4 hormone, and is then converted outside the thyroid to T3. The purpose of testing for both T4 and T3 is to evaluate if there is proper conversion between the two hormones, as well as if there is enough T3 to allow your body to function properly.
Reverse-T3 is an inactive form of thyroid hormone; it shouldn’t be high in your blood. If the levels are high, this indicates that your body is converting T4 to Reverse-T3, and not to the active form that causes your metabolism to work properly.
Total T4 and Total T3 are different from Free-T4 and Free-T3. A majority of Total T4 and Total T3 is made up of thyroid hormone that is bound to protein. When it’s bound to protein, it isn’t bioavailable to your cells. It is the “Free” form that is most important as this means that the thyroid hormone is freely circulating around your blood, unbound to anything, and able to be used when needed.
Signs and Symptoms of Low Thyroid Function
• Low body temperature (measured over time)
• Weight gain
• Feeling cold when others don’t
• Feeling jittery or anxious
• Appetite or taste buds altered
• Brain fog (can’t think clearly)
• Poor memory and/or concentration
• Low interest in sex (decreased libido)
• Thin and/or coarse or dry hair
• Loss of hair, especially the outer third of your eyebrows
• Dry skin
• Constipation (bowel movement every two or more days)
• Change in menses (periods)
• Pain in extremities (arms, legs, hands, feet)
• High blood pressure (hypertension)
There are additional blood tests that can be used to assess for proper thyroid function. Thyroid antibodies and Hashimoto’s thyroiditis can be detected using the thyroid peroxidase antibodies (TPO Ab) or anti-thyroglobulin antibodies (Tg Ab) tests. Other tests look for levels of thyroid-stimulating immunoglobulin (TSI)—which is associated with Graves’ disease—and iodine levels.
Some Causes of Thyroid Dysfunction
There are various reasons for thyroid dysfunction. These range from nutritional deficiencies—including diet, vitamins and minerals—to environmental toxins. Even medications that you are taking can affect your thyroid. Age and other medical conditions can also play a part in thyroid dysfunction.
Nutritional deficiencies can also be caused by fasting, starvation, anorexia, and protein or calorie malnutrition. Some of the deficiencies that can cause issues with thyroid function include:
• Vitamin A, E, B12, B2 and B3
• Minerals such as selenium, iodine, iron and zinc
•Amino acids such as cysteine and tyrosine
• Excess consumption of goitrogens in foods like cabbage, kale and Brussels sprouts can also disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. (There is a way to eat these vegetables without having an issue.)
• Hormone deficiencies—including cortisol, testosterone and estrogen imbalances—can also contribute to thyroid dysfunction.
• Environmental toxins like heavy metals (mercury, cadmium and lead) can influence nutritional deficiencies as well. Mercury can reduce or prevent the formation and conversion of thyroid hormone; exposure is usually from eating fish or from handling old broken thermometers incorrectly. Halogens such as perchlorate, chlorine, fluorine and bromine, are not only found in our environment but are in common substances like household products including drinking water, beverages, toothpastes and cleaning supplies. Perchlorates and chlorine inhibit iodine uptake while bromine displaces iodine and inhibits thyroid activity. Pesticides can decrease TSH, FT3 and FT4 levels while radiation from X-rays and CT-scan exposures can negatively influence function as well. Excesses of calcium, lithium, copper and/or soy impair conversion of T4 to T3.
• Medications—such as amiodarone, carbamazepine, lithium, phenobarbitone, phenytoin or rifampin—can induce goiters, an abnormal enlargement of your thyroid gland, and suppress thyroid function.
This article is intended for informational purposes only, and you should always be under the care of a licensed physician to be properly evaluated. This article is also intended to help increase awareness of the importance of conducting a well-rounded assessment of thyroid function. Additionally, conducting a thorough history of your present condition, investigating your past medical history as well as your family’s medical history, and performing a physical exam are important in determining your overall health. Lastly, conventional laboratory testing doesn’t always confirm or demonstrate a thyroid condition. A physician must use his/her clinical experience and training to help better assess the signs and symptoms of their patients to determine thyroid health and function.
1 There are many ways to evaluate if your thyroid is functioning properly, but for the purposes of this article, we focused on blood testing alone.
Salvatore Fiorentino, ND, MS, is a licensed naturopathic physician with offices in both Westport and Woodbury. Connect at DrSFiorentino.com or 203-864-5762.Edit ModuleShow Tags