Hyperthyroidism, or overactive thyroid, is a condition in which an excess of the thyroid hormones T3 and T4 are secreted into the bloodstream. Excess thyroid hormone leads to an increase in metabolism and increased energy needs. These energy needs are not always met in individuals with hyperthyroidism. They frequently suffer from muscle weakness because of decreased levels of carnitine, a compound that helps fatty acids enter the cell engines, or mitochondria. Clinical trials show that carnitine supplements may help to prevent muscle weakness and other detrimental effects of hyperthyroidism.
Hyperthyroidism
Hyperthyroidism is most commonly an autoimmune disease, a disease in which the immune system incorrectly attacks the thyroid gland. Serious cases of hyperthyroidism may lead to Graves’ eye disease, a disease in which the eyes bulge out of the head, and a potentially lethal condition known as thyroid storm. In thyroid storm, the heart beat is extremely fast and the blood pressure is sky high. Thyroid storm has a 50 percent mortality rate.
Metabolic Waste
When metabolism increases owing to the excess secretion of thyroid hormone, the body needs an excess of energy. A regular diet will not fulfill the new caloric needs. So, in most cases, the body starts breaking down its own tissues to produce sufficient energy. Both protein-rich tissue and fat tissue can provide energy for cells when the dietary intake does not cover the energy needs. So, hyperthyroidism leads to a wasting of muscles and fatty tissue. This, by itself, can lead to muscle weakness, but muscle weakness in hyperthyroidism often goes beyond a weakness associated with a wasting of muscle tissue.
Carnitine
Muscle weakness in hyperthyroid individuals is associated with a carnitine deficiency. Carnitine is a compound synthesized from the amino acids lysine and methionine. Its main job is to transport fatty acids into the mitochondria in muscle cells, which can then turn them into energy. Carnitine also has antioxidant properties that can prevent cell damage during the breakdown of fatty acids. It has been used as a supplement to increase bone mass in individuals with osteoporosis and to improve symptoms in individuals with heart disease.
Clinical Trials
The carnitine deficiency in hyperthyroidism prevents muscles from metabolizing fats and results in muscle weakness. In clinical trials, it has been shown that a carnitine supplement can help to prevent symptoms of hyperthyroidism, not by controlling the secretion of thyroid hormone from the gland, but by facilitating fat metabolism in muscle tissue. A study of 50 women with hyperthyroidism published in the August 2001 issue of “The Journal of Clinical Endocrinology and Metablism” found that carnitine, in combination with thyroid supplements, can completely remove symptoms of hyperthyroidism such as muscle weakness. A different study published in the January 2006 issue of “Annals of the New York Academy of Sciences” showed that carnitine could reduce the lethal effects of thyroid storms.
References
- Mayo Clinic: Hyperthyroidism
- Office of Dietary Supplements, National Institutes of health: Carnitine: The Science Behind a Conditionally Essential Nutrient
- University of Maryland Medical Center: Cartinine
- “Life Extension Magazine”; Carnitine and Thyroid Disease: Why Hyperthyroid Patients Need Carnitine; J.G. Goepp, MD; December 2007
- “The Journal of Clinical Endocrinology and Metablism”; Usefulness of l-Carnitine, A Naturally Occurring Peripheral Antagonist of Thyroid Hormone Action, in Iatrogenic Hyperthyroidism: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial; S. Benvenga, et al.; August 2001
- “Annals of the New York Academy of Sciences”; Effects of Carnitine on Thyroid Hormone Action; S. Benvenga, et al.; January 2006
Member Comments