Hypothyroidism: Causes and Management

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Hypothyroidism: What Is It?

Hypothyroidism is a term used to describe an underactive thyroid gland. Hypothyroidism is further classified according to “type”: subclinical, primary, or secondary hypothyroidism. The main function of the thyroid gland is to regulate the metabolic processes essential for normal growth, development, and tissue differentiation.[1] The thyroid gland can become “sluggish” for various reasons, as we will explore in more depth. Normally, the thyroid and peripheral tissues convert thyroxine (T4) into its more active form of triiodothyronine (T3). 

Thyroid hormone production is influenced by various factors, including thyrotropin-stimulating hormone (TRH) from the hypothalamus, the levels of thyroid stimulating hormone (TSH) released from the pituitary gland, and the availability of iodine and tyrosine. TSH production is regulated via means of a feedback loop between the hypothalamus, pituitary gland, and thyroid.[2] Hypothyroidism results in a slower basal metabolic rate (BMR), which ultimately leads to weight gain. Other signs and symptoms of hypothyroidism include irregular bowel movements (constipation), low energy, dry skin, hair loss, irritability, mental impairment, cold intolerance, joint/muscle pains, and delayed or absent reflexes, to name a few. Keep in mind that not every single one of these symptoms will necessarily be present with hypothyroidism.

What Causes Hypothyroidism?

A common cause of hypothyroidism is Hashimoto’s thyroiditis,[3] which affects an estimated 5% of the general population, making it one of the most prevalent autoimmune diseases. It is reported to occur in approximately 10–20% of all women, and less frequently in men.[4] Hashimoto’s is regarded as a disorder of T cell–mediated immunity,[5] with the infiltration of self-targeting T and B lymphocytes in the thyroid gland.[4]

Additional autoimmune conditions may be present in those who have a diagnosis of Hashimoto’s, so it is important to evaluate for coexisting autoimmunity.[5] Stress can play a crucial role in thyroid dysregulation, by triggering the release of noradrenaline, cortisol, and corticotropin-releasing hormone. These hormones have an inhibitory influence on TSH secretion and suppress enzymes involved in the conversion of T4 to T3.[6] Poor gastrointestinal (GI) health may also be responsible for autoimmune thyroiditis. Did you know that 70–80% of the immune system is found within the GI tract? Lifestyle factors such as stress, medication/antibiotic use, and poor diet directly impact the integrity and health of the GI tract. When the GI tract loses its integrity, the immune system can ultimately become confused, and the body makes mistakes! In the case of intestinal hyperpermeability, the immune system misidentifies normally harmless antigens (such as foods) as being foreign and mounts immune responses to them. The protein structure of certain foods resembles that of the thyroid, and cross-reactivity can occur as a result; the body can turn against itself, causing an autoimmune reaction. On a side note, poor GI health will also likely be evident as a result: bloating, gas, irregular bowel movements, heartburn, and abdominal cramps are possible, but are just some of the symptoms that correlate with poor GI health!

Screening

Your health-care practitioner will screen for signs and symptoms of an underactive thyroid. She/he will likely order a thyroid panel (possibly including iodine via a 24 hour urinary excretion test) to determine the state of the thyroid gland, and perform a physical exam to assess for nodules or irregularities. An ultrasound may also be ordered to assess the thyroid when nodules are palpated. In hypothyroidism, TSH tends to be elevated, with T4 and T3 being low.[6] Elevated thyroid peroxidase (TPO) and thyroglobulin (TG) antibodies on lab results signify that the thyroid is being “attacked.”

Natural Approaches to Treatment / Dietary Interventions

Gluten-Free Diet: The protein structure of gluten cross-reacts with that of the thyroid. Studies show that patients improve on a strict gluten-free diet. When people removed gluten from the diet, antibody levels decreased and thyroid function was restored. There may also be additional offending foods that need to be eliminated from the diet.[7] Increase Protein Intake: This is important, as protein is a precursor to both tyrosine and stress hormone production (e.g. catecholamines).[6]

Nutritional Interventions

Iodine—A micronutrient required for thyroid function and synthesis of thyroid hormones, iodine can be obtained in the diet from seafood, animals products, and fruits like cranberries and strawberries. Dose: Aim for about 150 mcg/d, unless pregnant or lactating (250 mcg/d).[5] Meanwhile, a number of studies indicate that moderate or mild iodine excess (> 220 mcg/d) is associated with a more frequent occurrence of hypothyroidism—the exact mechanism has not been clarified.[8] A recent study suggested that the apoptosis of thyroid follicular cells seen in hypothyroidism development is likely caused by suppression of autophagy activity which is induced by iodine excess. High doses of iodine should be discouraged in Hashimoto’s.[5]

Selenium—A micronutrient that increases active thyroid (T3) hormone production and modifies the inflammatory and immune response. In the absence of selenium, reverse T3 is produced (which is metabolically inactive). Selenium is particularly high in Brazil nuts and foods such as tuna and oyster. The recommended dietary intake is between 55 and 75 mcg/d. Three meta-analyses have confirmed a suppressive effect of selenium supplementation on TPO and TG antibodies. The patient groups in the latter study were receiving 200 mcg of selenomethionine. In order to predict whether a patient with Hashimoto’s would benefit for selenium supplementation, the clinician should first investigate the patient’s iodine status.[9]

Vitamin D—Several studies have shown a correlation between vitamin D deficiency and thyroid autoimmunity. Vitamin D supplements, especially skin exposure to sunlight, are both effective in reducing thyroid peroxidase antibodies in patients with vitamin D deficiency. Vitamin D has immunomodulatory function. It is important to get your vitamin D levels tested prior to supplementation—as it is a fat-soluble vitamin and therefore has the potential to accumulate in the body, leading to toxicity in high doses due to the buildup of calcium (hypercalcemia) and possibility of nephrolithiasis. In those at risk of heart disease, your health-care provider may also prescribe vitamin K alongside vitamin D. High vitamin K status is associated with reduced coronary artery calcification, cardiovascular disease, and mortality risk.[10]

Herbal Interventions

Withania somnifera: This herb is an adaptogen, in that it helps modulate the stress response and mitigates symptoms associated with stress. This herb supports the conversion of T4 to T3 and is thus beneficial for proper thyroid function.[6]

Conclusion

Hypothyroidism can result from an autoimmune attack, poor digestive health, nutritional deficiencies, as well as adrenal fatigue. Common approaches to treatment include eliminating food sensitivities and healing the GI tract, modulating the immune system and decreasing inflammation (in the case of Hashimoto’s), nutritionally providing the precursors necessary for thyroid function, and supporting the adrenal glands to reduce the impact of stress on the endocrine system. Naturopathic medicine addresses thyroid issues with diet, nutritional supplementation, and herbal medicines. Consult with your naturopathic doctor before self-diagnosing and initiating treatment for thyroid issues.