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Hypothyroidism
 

Hypothyroidism Introduction

Hypothyroidism is the clinical representation of having decreased levels of circulating thyroid hormones in a particular individual. There are two main thyroid hormones secreted by the thyroid gland, T4 and T3. Outside of the gland, T4 is broken down into T3 by specific enzymes. T4 does not affect the tissues in the body, as T3 is the active form of thyroid hormone.

  • Primary hypothyroidism can result due to a decrease in production from the thyroid, a decrease in conversion or breakdown of T4 to T3 in the body, or a decrease in the signal from the brain to tell the thyroid gland to make more hormone. [1] Secondary hypothyroidism results from removal of the thyroid gland, radiation of the gland, and from drug therapy.
  • Sub-clinical hypothyroidism is now seen as a condition that reflects low levels of thyroid hormones, with clinical symptoms, but is not diagnostic of hypothyroidism. [2] This form of hypothyroidism has garnered much interest within the medical community.

Hashimoto’s thyroiditis is an autoimmune disease that causes hypothyroidism as well. It is the result of anti-bodies attacking the signaling molecules responsible for hormone synthesis. Hashimoto’s is the most common cause of hypothyroidism in the US. In the past, the most common cause was iodine deficiency, but that problem was solved by adding iodine to table salt (iodized salt). [3]

The potential risks and development rates of hypothyroidism increase with age. It affects women ten times as often as men. In fact, Hashimoto’s affects women 8 times as often as men. It is estimated that between 1-4% of the US population has hypothyroidism. That number can possibly increase to 10-25%, if sub-clinical or mild hypothyroidism is included into the statistical equation. [4]

Hypothyroidism Signs and Symptoms

Symptoms of hypothyroidism include:

Clinical signs of hypothyroidism include, but are not limited to; goiter, decreased deep tendon reflexes, hoarse voice, brittle nails, dry skin, muscle weakness, low basal body temperature, and menstrual irregularities. [5]

Hypothyroidism causes a decrease in metabolism and an overall slowing of the systems of the body. Most body systems can be affected, including the cardiovascular, digestive, and neurological systems. Children with hypothyroidism can have mental deficits that result in mental retardation, and growth deficits that can be so severe that cretinism develops. [6]

Hypothyroidism Treatment

Treatment of hypothyroidism is focused on replacing the hormones. Today, there are several preparations available by prescription. Both T3 (liothyronine) and T4 (l-thyroxine) can be given alone or in combination. Both of those preparations are synthetic. Desiccated animal thyroid, USP Armour, may also be administered, as it too contains both T4 and T3. [7] Additional treatments for hypothyroidism focus largely on the metabolism of the hormones in and out of the thyroid gland. It is believed that a large percentage of hypothyroidism is caused by a disruption of the peripheral metabolism of the hormones, namely the conversion of T4 to T3. Supplementation with vitamins and minerals is focused on maintaining homeostasis of thyroid hormone metabolism.

Supplements helpful for Hypothyroidism

Iodine

In the past, iodine deficiency was the main cause of hypothyroidism, Iodine is necessary for the production of thyroid hormones. It is chemically bound to a specific amino acid responsible for the formation of the base structures for both T4 and T3. A deficiency in iodine causes a deficiency in thyroid hormone production, which often results in the development of hypothyroidism. Supplemental iodine is beneficial for patients with hypothyroidism. It may boost the production of thyroid hormones by providing more base materials.

Selenium

Selenium is the main co-factor for the enzyme responsible for the conversion of T4 to T3 in the peripheral tissues of the liver, kidney, and skeletal muscle. This conversion accounts for the majority of the metabolism concerning T4. A deficiency in Selenium results in decreased levels of T3 in the blood, with normal to high levels of T4. However, there is usually enough of a disruption from normal homeostasis to cause hypothyroidism.

In one study of children who exhibited symptoms of hypothyroidism, a deficiency of selenium was recognized. After Selenium supplementation, hormone levels returned to normal and symptoms disappeared. [8] Another study found that a low T3/T4 ratio in healthy elderly subjects could be corrected by supplementation with selenium. [9]

Zinc

The exact role of zinc in thyroid hormone metabolism is not completely understood, though it is viewed as a necessary component for proper thyroid function. Zinc deficiency has been shown to cause a decrease in T3, unrelated to thyroid production, and also a decrease in the conversion of T4 to T3. Zinc does not affect the levels of T4.

In one particular study, Zinc supplementation for 12 months caused T3 levels in the blood to normalize in all participants, 75% of whom were found to be deficient in zinc. [10]

Copper

Copper metabolism in the body is directly linked to zinc status. Supplementation with zinc can result in a copper deficiency, which can be dangerous. Therefore, when taking larger doses of zinc, supplementation with copper is also recommended.

Vitamin B12

Vitamin B12 is necessary for DNA and RNA synthesis, hormone synthesis, homocysteine metabolism, and is involved in function of the nervous system. Although the exact role of Vitamin B12 in thyroid hormone metabolism is not fully understood, it is believed to play a role in peripheral metabolism of T4 to T3. [11] Homocysteine is elevated in individuals with hypothyroidism. [12] Another study found that not only homocysteine elevation was paralleled to a decrease in vitamin B12 in individuals suffering from hypothyroidism. [13]

Folic Acid and Vitamin B6

Folic acid and B6 are also involved in homocysteine metabolism with Vitamin B12. To correct the increase homocysteine levels found in hypothyroid patients, the supplementation with all major nutrients is often needed. A deficiency of folic acid in individuals with hypothyroidism has also been reported in the literature of past study. [14]

DHEA

DHEA is a steroid hormone precursor that is produced by the body. It has been found to potentiate the thyroid hormone activity in certain individuals. [15] DHEA blood levels are decreased in patients with hypothyroidism. [16] Although the exact relationship between DHEA and thyroid hormones is not completely understood, DHEA remains a legitimate treatment option for those with hypothyroidism.

References

[1] Beers M and Berkow R. Hypothyroidism. The Merck Manual 17th Ed. Pp93-95.

[2] Beers M and Berkow R. Hypothyroidism. The Merck Manual 17th Ed. Pp93-95

[3] Pizzorno J, Murray M, and Joiner-Bey H. Hypothyroidism. The Clinician’s Handbook of Natural Medicine. Pp257-262.

[4] Powell D. Endocrinology and Naturopathic Therapies. 2nd Ed. Pp49-59.

[5] Beers M and Berkow R. Hypothyroidism. The Merck Manual 17th Ed. Pp93-95

[6] Beers M and Berkow R. Hypothyroidism. The Merck Manual 17th Ed. Pp93-95

[7] Beers M and Berkow R. Hypothyroidism. The Merck Manual 17th Ed. Pp93-95

[8] Pizzuli A and Ranjbar A. Selenium deficiency and hypothyroidism: a new etiology in the differential diagnosis of hypothyroidism in children. Biol Trace Elem Res. 2000 Dec; 77(3): 199-208.

[9] Olivieri O et al. Selenium, zinc, and thyroid hormones in healthy subjects: low T3/T4 ratio in the elderly is related to impaired selenium status. Biol Trace Elem Res. 1996 Jan; 51(1): 31-41.

[10] Nishiyama S et al. Zinc supplementation alters thyroid hormone metabolism in disabled patients with zinc deficiency. J Am Coll Nutr 1994; 13: 62-67.

[11] Stangl GI et al. Cobalt deficiency effects on trace elements, hormones, and enzymes involved in energy metabolism of cattle. Int j Vitam Nutr Res. 1999; 69: 120-126.

[12] Diekman MJ. Determinants of changes in plasma homocysteine in hyperthyroid and hypothyroid. Clin Endocrinol (Oxf). 2001 Feb; 54(2): 197-204.

[13] Lien EA et al. Plasma total homocysteine levels during short-term iatrogenic hypothyroidism. J Clin Endocriol. 2000 Mar; 85(3): 1049-1053.

[14] Lien EA et al. Plasma total homocysteine levels during short-term iatrogenic hypothyroidism. J Clin Endocriol. 2000 Mar; 85(3): 1049-1053.

[15] Powell D. Endocrinology and Naturopathic Therapies. 2nd Ed. Pp49-59.

[16] Tagawa N et al. Serum dehydroepiandrosterone, dehydroepiandroserone sulfate, and pregnenolone sulfate concentrations in patients with hyperthyroidism and hypothyroidism. Clin Chem. 2000 Apr; 46(4): 523-528.