Research as of 2011 shows that high cholesterol is not a known cause of thyroid disease. On the contrary, research shows that thyroid disease, specifically hypothyroidism, is a cause of high cholesterol. According to "European Journal of Endocrinology" in 1998, 10 percent of 98 million people diagnosed with high cholesterol have undiagnosed thyroid conditions. The "Archives of Internal Medicine" published a cross-sectional study in 2000 where the researchers statistically estimated that at least 13 million people nationwide live with undiagnosed hypothyroid disease. The same cross-sectional study revealed that close to 70 percent of the people with known hypothyroidism in their study had high total cholesterol. These statistics and other studies have encouraged more research on the thyroid-cholesterol connection.
Thyroid Disease
The thyroid is a butterfly-shaped gland located in the front of your neck just below your voice box. It is small, but can have a huge impact on your health, mentally and physically. The thyroid is approximately the width of your windpipe and produces hormones that affect every cell in the body. Imbalance of the hormones leads to two forms of thyroid disease, hypothyroidism and hyperthyroidism. Hypothyroidism is a condition caused by under-production of hormones. Hyperthyroidism is due to the over-production of thyroid hormones. Both conditions have different effects with varying degrees of outcome. For instance, it is known that untreated hypothyroidism leads to seriously high levels of cholesterol, where hyperthyroidism can lead to unhealthy levels of low cholesterol.
Connection Between Hypothyroidism and High Cholesterol
Two important hormones produced by the thyroid are triiodothyronine, or T3, and thyroxine, or T4. T4 is transported to the liver via blood where it is converted to T3. T3 aids in the breakdown of lipids, primarily low-density lipoproteins known as "bad" cholesterol, under normal circumstances. In hypothyroidism, the thyroid is unable to produce adequate amounts of T4 for circulation. Low T4 levels result in low levels of T3. Cholesterol levels rise because there is not enough T3 to break it down. High cholesterol is a serious condition that can lead to atherosclerosis or hardening of the arteries and block blood flow.
Common Causes of Hypothyroidism
There are several causes that lead to an underactive thyroid but high cholesterol is not known to be one of them. Hypothyroidism is triggered by overtreating hyperthyroidism, a bacterial or viral infection that triggers an autoimmune response, surgical removal of all or part of the thyroid gland, cancer radiation therapy or genetics. Hypothyroidism symptoms manifest in many physical and mental functions. The low production of hormones causes a decrease in energy metabolism, which results in constipation, weight gain, fatigue, lower body temperature and low libido. Mental symptoms include short attention span, anxiety and depression. Other symptoms include brittle nails, loss of hair, missed menstrual cycles and dry skin.
Thyroid Hormone Therapy
Traditional treatment of hypothyroidism is levothyroxine, synthetic T4. It is converted to T3 in the tissues over time and is believed to provide adequate amounts of T3 to bring the thyroid to a normal functioning state. Recently studies have found that people had favorable results mentally and physically with a combination of T4 and T3 medication over just T4 medication. However, combination T3/T4 therapy is inconclusive for lowering cholesterol based on the number of conflicting studies reviewed. For example, a 2002 "Hormones" review found that individuals did show improved cholesterol levels with treatment involving only T4 treatment as their thyroid approached a normal functioning state. A 2010 "Hormones" study found slight improvement of total cholesterol with combined T3/T4 therapy. Each individual is different so consult with your physician to discuss thyroid and high cholesterol therapy.
References
- "European Journal of Endocrinology"; High serum cholesterol levels in persons with 'high-normal' TSH levels: should one extend the definition of subclinical hypothyroidism?; Georgia Michalopoulou, et al.; 1998
- "Archives of Internal Medicine"; The Colorado Thyroid Prevalence Study; Gay J. Canaris, MD, MSPH, et al.; 2000
- MayoClinic.com; Hypothyroidism (underactive thyroid); 2010
- "Hormones"; Dyslipidemia in Patients with Thyroid Disorders; E. Liberopoulous and M. Elisaf; 2002
- "Hormones"; Combined therapy with L-thyroxine and L-triiodothyronine compared to L-thyroixine alone in the treatment of hypothyroidism; Valentine V. Fadeyev, et al.; 2010
