The Relationship Between the Thyroid and High Cholesterol
Thyroid function regulates a wide range of metabolic processes. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) take on a wide range of jobs in the body, and their production is controlled by thyrotropin (TSH). The relationship between the thyroid and high cholesterol is very close, so much so that the decrease or increase in its values can be caused by thyroid dysfunction.
People who suffer from thyroid disease (hypothyroidism and hyperthyroidism) are prone to experience changes in their cholesterol levels. The imbalance in the gland can also affect triglyceride levels, which, along with cholesterol levels, increase the chances of developing a heart condition. We’ll show you what is known about the connection between the thyroid and high cholesterol.
How are thyroid and high cholesterol related?
Cholesterol is a substance found in all cells of the body. The body produces it naturally, although diet, genetic factors, and some conditions can increase or decrease its production. Broadly, there are two types of cholesterol of clinical importance:
- High-density lipoprotein or HDL cholesterol (known as good cholesterol).
- LDL low-density lipoprotein cholesterol (known as bad cholesterol).
As the experts point out, the main function of cholesterol is to maintain the integrity and fluidity of cell membranes and to mediate as a precursor for the synthesis of vital substances for the body (such as steroid hormones, bile acids, and vitamin D). ). A decrease in its values interferes with these functions, while an increase results in fatty deposits in the blood vessels.
For its part, the thyroid is a small butterfly-shaped gland located in the neck. It secretes the hormones T3 and T4, which help control metabolism. Episodes in which the gland doesn’t secrete enough thyroid hormones are known as hypothyroidism. In contrast, it is called hyperthyroidism when it produces more than it should.
Investigators have linked hypothyroidism with dyslipidemia (hypercholesterolemia and hypertriglyceridemia). It’s believed that the decrease in thyroid hormone in the body affects the synthesis, metabolism, and mobilization of fats.
T3 and T4 increase the activity of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-COA) reductase in the liver and therefore lower cholesterol.
In addition to this, they also increase LDL receptors in fibroblasts, liver, and other tissues, and increase the absorption of cholesterol in the intestine. It’s for this reason that changes in their normal values directly affect the increase in blood cholesterol.
The relationship between the thyroid and high cholesterol had already been reported by Mason et al in 1930, although it wasn’t until recently that the connection was understood.
As the experts point out, both hyperthyroidism and hypothyroidism can cause imbalances in cholesterol levels through indirect routes. We summarize the most important:
- They affect the metabolism of adipocytes
- They regulate the production of adipokines
- They increase adiponectin levels (in hyperthyroidism)
- They negatively affect insulin sensitivity
- They promote oxidative stress
- They can affect endothelial function, cardiac function, and promote atherosclerosis
- They can affect body mass index (BMI) and waist circumference
All these alterations as a whole consolidate the relationship between the thyroid and high cholesterol. Although these values by themselves don’t affect cholesterol, they do in connection with others or indirectly.
Keep in mind that people with high cholesterol are at higher risk of developing heart disease, mood disorders, and some types of cancer.
Treatment of high cholesterol and thyroid disease
Both high cholesterol and thyroid disease can be controlled. We have already mentioned the complications related to an increase in blood cholesterol, so it isn’t an alteration that should be ignored.
In the case of thyroid disease, these can cause mental disorders (such as anxiety or depression), sleep disorders, and muscle weakness, among others.
Hypothyroidism is treated with the help of the medication levothyroxine. This is a drug that contains a synthetic form of T4.
By controlling the levels of the hormone, cholesterol will also return to normal levels, but it isn’t uncommon for other medications to be prescribed to promote it. For example, the intake of statins (atorvastatin and rosuvastatin) and PCSK9 inhibitors (evolocumab and alirocumab) may be suggested.
Hyperthyroidism is treated with what are known as antithyroid medications, such as methimazole. You may also opt for radioactive iodine therapy or surgery to remove your thyroid. Apart from drug-based treatment, some lifestyle changes must be made. The most important are the following:
- Implement a balanced diet
- Lose weight
- Exercise regularly
- Give up smoking
- Drink alcohol in moderation
- Reduce stress levels on a daily basis
The chosen roadmap will be determined by the specialist based on the characteristics of each patient. If your routine exams reflect an increase in your cholesterol levels, be sure to consult a specialist. It’s also a good idea to visit your health professionals regularly if you have been diagnosed with a thyroid disease.
- MASON, R. L., Hunt, H. M., & Hurxthal, L. (1930). Blood cholesterol values in hyperthyroidism and hypothyroidism—their significance. New England Journal of Medicine. 1930; 203(26): 1273-1278.
- Rastgooye Haghi A, Solhjoo M, Tavakoli MH. Correlation Between Subclinical Hypothyroidism and Dyslipidemia. Iran J Pathol. 2017;12(2):106-111.
- Rizos CV, Elisaf MS, Liberopoulos EN. Effects of thyroid dysfunction on lipid profile. Open Cardiovasc Med J. 2011;5:76-84.
- Zampelas A, Magriplis E. New Insights into Cholesterol Functions: A Friend or an Enemy?. Nutrients. 2019;11(7):1645. Published 2019 Jul 18.