How a Healthy Thyroid Functions
Yhe thyroid is a small, butterfly-shaped gland that sits just below your larynx, or Adam’s apple. It weighs less than an ounce and is made up of two halves called lobes that lie along the trachea. It’s controlled by a small, peanut-shaped gland in the brain called the pituitary.
When the levels of thyroid hormones drop too low, the pituitary will produce thyroid-stimulating hormone (TSH), which in turn stimulates the thyroid to make more hormones. As the levels of thyroid hormones rise in the blood, the pituitary senses the elevation and decreases TSH levels. Conversely, when thyroid hormones lower in the blood, TSH levels rise.
The pituitary gland is controlled by the hypothalamus. It’s the hypothalamus that tells the pituitary to produce TSH. It does this by producing thyroid-releasing hormone (TRH)
Once stimulated, the thyroid gland takes up iodide from the foods we eat and converts it into iodine to make the thyroid hormones thyroxine (T4) and triiodothyronine (T3). The thyroid cells convert iodide into iodine inside of the gland using a process that requires hydrogen peroxide (H2O2) With the help of an enzyme called thyroid peroxidase (TPO), it combines the iodine with the amino acid tyrosine on the backbone of thyroglobulin protein molecules, and thyroglobulin splits and forms the thyroid hormones T4 and T3. These hormones are then released into the bloodstream where they are essential to the development of literally every cell in the body.
The thyroid produces both T4 and T3, but T3 is approximately three times more potent than T4 and is the active form of the hormone. In order to get more T3, a healthy body will convert roughly 60 percent of the circulating T4 into T3. This process occurs mostly in the liver by an enzyme called iodothyronine 5’ deiodinase. The remaining T4 is converted to T3 in a healthy GI tract. If you have a healthy liver and GI tract you’ll be optimally converting T4 into T3 and feel great! If your liver and GI tract are compromised in some way, the conversion will not take place at adequate levels, and signs of hypothyroidism will be present.
Some common reasons your liver might not be converting T4 to T3:
- Trans fats
- Advanced glycation end products (AGE’s)
- High carbohydrate diet
- Leaky gut and selenium deficiency
- Heavy metals
- Petrochemicals and other toxins
- Infections such as Candida
If you have been diagnosed with an autoimmune thyroid condition, in fact any autoimmune condition, supporting your liver is critical to recovery!
Your Thyroid is your Body’s Furnace
Think of your thyroid gland as your body’s furnace, and your pituitary gland as its thermostat. When the furnace (thyroid) gets too cold, the thermostat (pituitary) will sense it and produce TSH to stimulate the production of thyroid hormones, which effectively turns up the heat. When the levels of thyroid hormones rise and the furnace gets hot, the pituitary slows the production of TSH, which turns the heat down.
Why We Need Optimal Thyroid Hormone Levels
Just Google “the role of thyroid hormones” and you will find thousands of scholarly articles that have been written on the functions of thyroid hormones. Thyroid hormones regulate the metabolic functions of literally every cell in the body—from brain chemistry to digestion. Maintaining optimal thyroid hormone levels are important to achieving and maintaining vibrant health.
Let’s take a brief look at some of the areas where they play a key role:
Body Weight and Metabolism: Ultimately, your body temperature and metabolism affect your body composition. If the hormones are too high, you feel hot all the time, and you may become too thin. If your hormones are too low, you feel cold all the time, and you will burn fewer calories and gain weight. Thyroid hormones assist in the conversion of food into energy and heat. Low thyroid hormones slow down the conversion of glucose and fat into energy, which results in a slow metabolism and weight gain—even on restricted calorie diets. It also impairs the production of human growth hormone (HGH), which is needed to make lean muscle mass.
Stress: Optimal thyroid hormones are needed to produce the adrenal hormones cortisol and DHEA, which help us to manage stress. Both hyperthyroidism and hypothyroidism play a role in adrenal fatigue and exhaustion, resulting in low levels of these protective hormones.
Sex Hormones: Low thyroid hormones can cause an imbalance of testosterone, estrogen and progesterone leading to many conditions such as infertility, low libido, weight gain, menstrual problems, symptomatic menopause, polycystic ovarian syndrome, hair loss and the risk of certain cancers that are associated with imbalanced sex hormones.
Aging: Thyroid hormones regulate the production of human growth hormone (HGH). Low thyroid hormones depress this important hormone leading to accelerated aging, osteoporosis, skin wrinkles, increased body fat, low energy levels, and decreased lean muscle mass.
Immune System: Thyroid hormones play a crucial role in the development and regulation of the cells involved in both humeral and cell-mediated immunity, thus protecting the body from infections and viruses. This is why individuals with low levels of thyroid hormone suffer from chronic infections.
Brain Function: Hypothyroidism depletes pregnenolone, which is often called the “mother” of all hormones because it is a key building block in the production of all steroid hormones. It acts to improve memory and combat depression, and it also has powerful anti-inflammatory properties. Thyroid hormones also affect brain chemistry by stimulating and regulating the action of neurotransmitters such as serotonin, norepinephrine, and GABA (gamma aminobutyric acid). These neurotransmitters are important in the regulation of anxiety, mood, sleep, appetite and sexuality.
Cardiovascular System/Cholesterol Levels: Optimal thyroid hormones protect against heart disease by normalizing homocysteine levels in the blood. They regulate circulation, increasing blood supply to the hands, feet and surface of the skin. Increased blood supply delivers essential fatty acids and nutrients, which keep the skin soft and healthy. Hypothyroidism slows metabolism, which decreases the liver’s ability to clear cholesterol from the blood, resulting in high cholesterol and triglycerides. Low thyroid levels are frequently associated with hypercholesterolemia and may increase the risk of atherosclerosis. Low thyroid hormones can cause an enlarged heart and impair the heart’s ability to pump efficiently.
Digestion: Low levels of thyroid hormones cause constipation, and slow the production of stomach acid by depleting the hormone gastrin. Hyperthyroidism can cause diarrhea and rapid transit time of food through the GI tract. Both of these conditions increase the risk of chronic GI infections from harmful yeast and bacteria and can lead to inflammation, malabsorption, nutrient deficiencies, leaky gut, food allergies and uncomfortable GI symptoms such as gastroesophageal reflux disease (GERD).
Liver and Gallbladder Function: Thyroid hormones help the liver and gallbladder to function optimally, which affects detoxification, hormone production and the conversion of T4 to T3.
Anemia: Hypothyroidism can cause a decrease in the number of red blood cells that carry oxygen to the body’s tissues. This condition is called anemia, which produces symptoms of pronounced fatigue.
Blood Sugar Regulation: Thyroid hormones regulate the absorption of glucose into the cells as well as the elimination of excess glucose. Hypothyroidism slows the rate of absorption and elimination, resulting in symptoms of hypoglycemia or dysglycemia.
Ideal Body Temperature: According to researchers at Albert Einstein College of Medicine, “98.6 degree body temperature strikes a perfect balance: warm enough to ward off fungal infection but not so hot that we need to eat nonstop to maintain our metabolism.” Thyroid activity is directly related to body temperature as thyroid hormones govern your basal metabolic rate to generate energy (or heat). A classic indicator of poor thyroid function is feeling cold (or hot for hyperthyroidism). This may be why so many people with low thyroid hormones suffer from chronic fungal infections!
As you can see, the body needs optimal thyroid hormones to be healthy. When thyroid hormones become imbalanced and are too high, or, more commonly, too low, we begin to experience some pretty severe symptoms.
There are many reasons our thyroid hormones can become imbalanced—from nutrient deficiencies and adrenal fatigue to conditions of the pituitary gland and other illnesses.
Michelle Corey, C.N.W.C., FMC, is a Wellness Recovery Specialist, Certified Nutrition and Wellness Consultant, researcher and author. Michelle studied holistic nutrition at Clayton College of Natural Health and completed a comprehensive 2-year practical program at Academy of Functional Medicine and Genomics. Since reversing her autoimmune condition, Michelle has helped hundreds of people reverse autoimmune and other chronic conditions. She is currently an advisor to the Academy of Functional Medicine and Genomics and the Functional Medical University. She is a member of the Institute of Functional Medicine and the National Association of Healthcare Advocacy Consultants. Michelle and offers Functional Mind-Body healing retreats, workshops and online courses.
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