An underactive thyroid, commonly known as hypothyroidism, is a condition that affects many people, including about 20 million Americans. Optimal thyroid functioning is important because the thyroid influences many systems in the body. It is so significant that newborns are screened for thyroid issues shortly after birth, as imbalances in thyroid hormone levels at this age could impact health.
This article will discuss hypothyroidism, its causes, and common signs and symptoms. Additionally, hypothyroidism testing and integrative approaches to support thyroid health will be discussed.
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What is Hypothyroidism?
Hypothyroidism occurs when the thyroid gland in the neck does not produce enough thyroid hormones. These hormones are used by many cells in the body, meaning hypothyroidism can have widespread effects.
The Hypothalamic Pituitary Thyroid (HPT) axis is a feedback loop that helps regulate thyroid function. When the body needs more thyroid hormone, the hypothalamus releases Thyroid-Releasing Hormone (TRH) to the pituitary gland, which then sends Thyroid Stimulating Hormone (TSH) to the thyroid gland. In response, the thyroid produces two main hormones, thyroxine (T4) and triiodothyronine (T3). T4 is the primary hormone produced, but T3 is more active in metabolism. T4 must be converted to T3, and this occurs in peripheral tissues such as the liver and kidney. Additionally, T4 can convert into another hormone, reverse T3 (rT3), which is not active in metabolism.
The amount of circulating thyroid hormones sends a feedback signal to the hypothalamus in the brain, and further output of TRH and TSH depends on this amount. Under normal conditions, when the thyroid hormone supply is sufficient, TSH release is sustained. When thyroid hormones are low, the hypothalamus senses the low level, and HPT activation occurs, leading to an increase in TSH. Conversely, when thyroid hormones are high, that will suppress TSH production.
In hypothyroidism, there is a miscommunication in this process. Low circulating thyroid hormones are sensed by the hypothalamus, leading to elevated levels of TSH. However, in hypothyroidism, the thyroid gland does not respond; thus, thyroid hormones remain low. This presentation of high TSH with low thyroid hormones is indicative of hypothyroidism.
There is a condition called subclinical hypothyroidism, which occurs when TSH is elevated, but thyroid hormones are normal.
What Causes Hypothyroidism?
Hypothyroidism can be caused by surgical removal of the thyroid gland, thyroid gland inflammation (thyroiditis), hypothyroidism present at birth (congenital hypothyroidism), radiation treatment of the thyroid, certain medications, pituitary and hypothalamic disorders, and iodine imbalances. Additionally, the most common cause of hypothyroidism is the autoimmune condition Hashimoto's thyroiditis. Hashimoto's thyroiditis occurs when the immune system mistakenly targets the thyroid gland, leading to inflammation and eventually low thyroid hormone output. Hashimoto's thyroiditis is most common in women and seems to be hereditary.
Certain conditions may increase the risk of hypothyroidism, including type 1 or type 2 diabetes, pernicious anemia, Sjogren's syndrome, Celiac disease, Rheumatoid arthritis, and lupus.
Hypothyroidism Symptoms
Signs and symptoms of hypothyroidism can vary depending on age, sex, and other factors. Common symptoms include fatigue, feeling cold, weight gain, joint and muscle pain, dry skin, hair loss, irregular periods and fertility problems, constipation, shortness of breath, mood changes, and memory problems.
If not managed, hypothyroidism can lead to serious health issues that require medical attention. It may also increase the risk for cardiovascular concerns, nerve issues, fertility challenges, and thyroid gland enlargement.
Ultimate Guide to Hypothyroidism Lab Testing
Most conventional doctors will test for TSH levels to screen for thyroid function and health. However, it is estimated that a TSH screening alone may not detect all thyroid issues.
A functional medicine approach may include a full thyroid panel and other specialty lab testing to get a clearer picture of how the body is converting and making thyroid hormones.
Complete Thyroid Panel
A complete thyroid panel, such as the thyroid panel by Precision Point, assesses TSH, T4, T3, free T4, free T3, reverse T3, and thyroid antibodies TPO and Tg. Thyroid testing should be done consistently in the morning, and any patient taking biotin should avoid its use prior to testing, as biotin can falsely alter results.
Comprehensive Stool Testing
A comprehensive stool test, such as GI360 by Doctor's Data, measures short-chain fatty acids (SCFAs), including their byproducts, zonulin (a marker of intestinal permeability), shows levels of numerous microbes of the microbiome, and assesses markers of digestion and absorption, all of which can aid in the evaluation of thyroid functioning. Thyroid hormones and SCFAs may help maintain tight junctions in the small intestine, potentially supporting intestinal health. Zonulin levels are increased in autoimmune conditions such as Hashimoto's thyroiditis. Also, dysbiosis, or an imbalance of good and bad bacteria in the microbiome, may influence the development of autoimmune conditions. Additionally, the levels of the bacterial family Lactobacillaceae and bacteria species Bifidobacteria, two of the most beneficial microbes in the GI tract, are reduced in Hashimoto's thyroiditis. Lastly, GI functioning includes absorbing nutrients necessary for optimal thyroid functioning.
Small Intestine Bacterial Overgrowth
SIBO testing, such as the Triosmart test by Gemelli Biotek, checks for large amounts of microbes in the small intestine. These microbes are translocated from the microbiome in the large intestine, where they should be. When present in large amounts in the small intestine, they can cause problems such as increased inflammatory markers, destruction of tight junctions, and more. There has been a correlation between SIBO and hypothyroidism, as hypothyroidism can cause lowered gastrointestinal motility, and SIBO symptoms can mimic and exacerbate hypothyroid symptoms. Lastly, as discussed in comprehensive gut testing, SIBO can affect the absorption of nutrients, some of which are implicated in hypothyroidism.
Micronutrient Panel
A micronutrient panel can help to assess thyroid functioning. Many nutrients, including selenium, iron, and vitamin D, are required for proper thyroid physiology; thus, testing levels to ensure adequate levels can be beneficial.
Liver Function Panel
Liver function plays an essential role in thyroid physiology. The liver aids in converting T4 into T3 and is also where these hormones are metabolized.
Other Lab Test to Check
Additionally, the following labs may be considered as their markers can be affected by hypothyroidism:
- Cholesterol panel: Hypothyroidism can be associated with elevated cholesterol and triglyceride levels, both of which are risk factors for cardiovascular health.
- Complete blood count (CBC). Iron is a required nutrient for thyroid hormone synthesis and more, and thus may be deficient in hypothyroidism. Low iron can also cause iron deficiency anemia (IDA), characterized by low red blood cells and low circulating oxygen. A CBC will be able to detect IDA.
- Prolactin: Prolactin is a hormone made by the brain's pituitary gland that causes milk duct activation in the breast tissue. Elevations in TRH and TSH can cause increased production of prolactin.
- Female hormone panel: Thyroid hormones may affect female hormones, fertility, and menstrual cycles due to ovulatory changes. Additionally, elevated prolactin can cause menstrual irregularities.
- Male hormone panel: Lack of thyroid hormones can affect testicular function, including sperm production. Like female hormones, high prolactin may also alter male hormones, sperm, and testosterone production.
A thyroid ultrasound may be required if abnormal findings are found on a physical exam. Ultrasounds are painless procedures that use sound waves to produce images.
Conventional Medicine Treatment for Hypothyroidism
Since the thyroid affects many systems of the body, replacement of thyroid hormone in the form of medication is often used to manage hypothyroidism.
The primary medication recommended for hypothyroidism is levothyroxine, which is synthetic T4. There are also medications containing T3 and medications containing both T4 and T3. Additionally, thyroid hormones can be compounded through a compounding pharmacy.
Thyroid levels will often be rechecked 6-8 weeks after the start of medication. Thyroid medication may then be checked every six months after that.
It's important to note that thyroid medication must be taken alone as nutrients can interfere with absorption. Timing will vary, usually from 30-60 minutes, depending on the type of medication.
Lastly, many patients on thyroid medication still report hypothyroid symptoms. This is where an integrative medicine approach can be helpful, as integrative therapies may help to support overall well-being.
Nutrition for Hypothyrodism
Consider exploring the reduction or elimination of gluten. Gluten may influence zonulin levels, a protein found in the GI tract that can affect tight junctions. Zonulin levels are increased in autoimmune conditions, so if Hashimoto's thyroiditis is present, it may be beneficial to monitor symptoms when reducing wheat intake.
Iodine is an essential nutrient for thyroid functioning as it's required to synthesize T4 and T3. However, too much or too little iodine can impact thyroid health. Consuming iodine through foods may be a way to help maintain proper levels and avoid excess intake and deficiencies. Iodine-rich foods include seaweed, seafood, and iodine-fortified foods such as milk products and salt.
Supplements for Hypothyroidism
Iron, vitamin D, and selenium are all required cofactors for thyroid physiology. Iron is necessary for thyroid cells to utilize iodine and for the production of thyroid hormones. Vitamin D, zinc, and selenium are required to synthesize thyroid hormones properly. Zinc and selenium are necessary for the conversion of T4 into T3. Zinc also aids in the utilization of T3 by cells via its function on receptors. Selenium supplementation has also been shown to support thyroid health.
Magnesium deficiency has also been associated with thyroid health. In a study of over 1,200 Chinese people, magnesium deficiency was linked with a higher rate of Hashimoto’s thyroiditis and hypothyroidism.
As discussed above, the microbiome may play an important role in thyroid physiology. A randomized control trial showed improved TSH and fatigue when a supplement with probiotics and prebiotics was given. Additionally, thyroid medication needed to be adjusted.
Summary
The thyroid gland is a vital organ that influences many body systems. Hypothyroidism, therefore, can significantly affect a person's quality of life. Proper thyroid testing is essential not only for the diagnosis of hypothyroidism but also for monitoring health. As the GI tract, nutrients, and liver function can impact thyroid health, labs assessing these areas may be considered. Additionally, due to the thyroid's system-wide effects, testing outside of evaluating the thyroid gland may also be considered.
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