Is There a Link Between Your Thyroid and Your Cholesterol?

Thyroid Problems May Be the Cause of Your High Cholesterol

Cholesterol levels and thyroid disease are linked. istockphoto

High cholesterol is a common health problem among Americans and a major contributor to heart disease.

Yet you may be surprised to learn that a poor diet and insufficient exercise are not always the culprits behind a person's high cholesterol. In fact, an easily treatable and secondary cause of high cholesterol is an underactive thyroid (called hypothyroidism).

Understanding Cholesterol

Cholesterol is a waxy substance found in animal foods, like meat and full-fat dairy products.

Cholesterol is also manufactured naturally in your liver where it's transported by fat-carrying proteins in the blood.

There are two types of cholesterol—LDL is your "bad" cholesterol and HDL is your "good" cholesterol. The reason LDL is bad is that as it travels through your bloodstream, it may form a hard deposit in the walls of arteries. Eventually, these fatty deposits make the arteries narrow and less flexible (this condition is called atherosclerosis).

Then, if a clot develops and blocks one of these narrowed arteries, blood flow cannot reach vital organs like your heart and brain; so, as a result, a heart attack or stroke may occur. 

Understanding the Link Between Cholesterol and Hypothyroidism

The thyroid, a butterfly-shaped gland located behind and below your Adam's Apple, produces a hormone that helps regulate your metabolism and facilitates the delivery of oxygen and energy to cells, tissues, and organs.

In addition to several other important metabolic functions in your body, when your thyroid produces too little hormone (called hypothyroidism), your ability to process cholesterol may also be impaired. More specifically, hypothyroidism is associated with elevated LDL and total cholesterol levels.

Due to the fact that hypothyroidism is present in up to 13 percent of people with high cholesterol, professional societies like the National Cholesterol Education Program, American Association of Clinical Endocrinologists, and the American Thyroid Association all recommend screening for hypothyroidism in people who are newly diagnosed with high cholesterol (before starting them on a cholesterol-lowering medication).

This is because cholesterol levels can improve by treating the hypothyroidism. In fact, according to a study in JAMA Internal Medicine, over sixty percent of people with high cholesterol and untreated hypothyroidism had normalization of their cholesterol levels once their thyroid function normalized.

Even more, a caveat in this study was that in many instances the people diagnosed with both high cholesterol and hypothyroidism never had a repeat cholesterol panel (once their thyroid disease was treated). With that, it's possible that more than sixty percent of people had a resolution of their high cholesterol after their hypothyroidism resolved. 

A Word From Verywell

If you or a loved one is newly diagnosed with high cholesterol, it's sensible to remind your doctor to screen you for hypothyroidism. This can be easily done with a blood test that measures your thyroid-stimulating hormone, or TSH.

If your TSH is found to be elevated (and you are diagnosed with hypothyroidism), taking thyroid hormone replacement will not only make you feel better, but it will also benefit your heart health.

Sources:

American Heart Association. (2017). About Cholesterol.

Garber JR et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012 Nov-Dec;18(6):988-1028.

Tagami T et al. Multi-center study on the prevalence of hypothyroidism in patients with hypercholesterolemia. Endocr J. 2011;58(6):449-57.

Willard DL, Leung AM, Pearce EN. Thyroid function testing in patients with newly diagnosed hyperlipidemia. JAMA Intern Med. 2014 Feb 1;174(2):287-89.