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People with a thyroid disease called hypothyroidism have an underactive thyroid gland. This means their thyroid gland doesn’t produce enough thyroid hormones, and they have low thyroid hormone levels in their bodies. Such individuals can develop high cholesterol as a result of their thyroid disorder. 

Taking thyroid hormone therapy to treat thyroid disease can lead to an improvement in cholesterol levels. In some cases, doctors can decide to initiate cholesterol-lowering medication in addition to thyroid medication to achieve desirable cholesterol levels. 

High blood cholesterol is associated with an increased risk of heart attacks, stroke, and other heart disease. Therefore, keeping your cholesterol levels under control lowers the risk of heart disease associated with high cholesterol. Please continue reading to learn more about the connection between thyroid disorders (underactive or overactive thyroid) and cholesterol levels.

How can I lower my cholesterol with an underactive thyroid?

Here are some ways to manage your conditions if you have an underactive thyroid and high cholesterol:

• Take your thyroid replacement hormones as prescribed by your doctor. Untreated hypothyroidism can lead to high cholesterol levels.

• Keep all your medical and laboratory appointments for thyroid function testing. Your doctor will measure thyroid stimulating hormone (TSH) and adjust your levothyroxine dose based on thyroid hormone levels.

• Follow your doctor’s dietary recommendations and limit your intake of saturated fat.

• Your doctor will determine how often to order blood work for your lipid panels. Serum lipid profiles or lipid panel is a blood test that measures different types of fats in the blood, such as low-density lipoprotein (LDL) cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol. 

• As a matter of fact, thyroid function testing is often ordered for patients with newly diagnosed hyperlipidemia. 

• Some people may need to take cholesterol medication even though their thyroid hormone levels are within normal ranges. Your doctor will determine if you need to be taking one of the cholesterol-lowering medications if your cholesterol continues to be high despite normal thyroid hormone levels and good adherence to lifestyle changes such as diet and exercise.

Can levothyroxine lower cholesterol?

Our body needs thyroid hormones to regulate cholesterol effectively. Therefore, taking levothyroxine for an underactive thyroid may help in treating high cholesterol. This thyroid medication is the synthetic form of the natural thyroid hormone thyroxine (T4). Levothyroxine is used to improve thyroid health and achieve normal thyroid function in people with hypothyroidism. 

Levothyroxine works by replacing or supplementing thyroid hormones in people with thyroid dysfunction. Patients treated with thyroid replacement hormones (levothyroxine) may achieve lower LDL (bad) cholesterol levels.

Can you take statins if you have an underactive thyroid?

If you have hypothyroidism (underactive thyroid) and increased cholesterol levels, your doctor will first prescribe thyroid hormone replacement (levothyroxine) to treat your thyroid disorder. This is because your underactive thyroid may be the cause of your increased cholesterol levels, and the treatment of hypothyroidism may bring your cholesterol level down without the need for cholesterol-lowering drugs. 

If treating hypothyroidism does not control your cholesterol, your doctor may then start you on one of the cholesterol medications such as statins. Note that statins are more likely to cause muscle damage in people with hypothyroidism. Learn which statin has the least amount of side effects.

What is the best diet for hypothyroidism and high cholesterol?

The same lifestyle changes and dietary modifications can help in managing both hypothyroidism and high cholesterol levels.

Hypothyroidism is associated with a slowed metabolic rate, so healthcare providers recommend cutting back on sugary snacks, fried foods, and processed foods to prevent weight gain. These dietary recommendations also help to reduce the intake of saturated fats, which helps to reduce cholesterol levels. Read “7 Foods & Beverages to Help Lower Cholesterol.”

Doctors also recommend limiting the intake of goitrogenic foods such as cruciferous vegetables (cabbage, broccoli, kale, bok choy, turnip) as they can interfere with the production of thyroid hormones. However, these foods only have a major effect if they are consumed in large quantities or if there is an iodine deficiency. 

Some people with hypothyroidism benefit from reducing or eliminating gluten from their diet. However, there is no scientific evidence to support that gluten (a protein found in wheat products) has an effect on thyroid function. Nonetheless, going gluten-free may help to prevent gas and constipation, which are common symptoms of hypothyroidism.

Learn what to eat for lower cholesterol.

What is cholesterol?

Cholesterol is a waxy substance made by the liver. Despite its bad reputation for causing heart disease, our body requires cholesterol for many essential body functions. However, when there’s too much cholesterol in the blood, it can clog blood vessels, raise blood pressure, and increase the risk of coronary heart disease. It is important to manage cholesterol for good cardiovascular health. Your liver and cholesterol: What’s the connection?

In addition to a sedentary lifestyle, people who eat an unhealthy diet with large amounts of dietary cholesterol are at an increased risk of cardiovascular disease. Eating a healthy diet can help prevent cholesterol-related health problems. Check out our blog: “Understanding Cholesterol: Dyslipidemia vs Hyperlipidemia.”

What is an overactive and underactive thyroid?

An underactive thyroid means the thyroid gland does not make enough thyroid hormones; this condition is called hypothyroidism. It occurs due to various causes, including autoimmune conditions such as Hashimoto’s thyroiditis, thyroid surgery, and radioactive iodine therapy. 

In contrast, hyperthyroid patients have an overactive thyroid gland. This condition is called hyperthyroidism. People with this thyroid condition have high levels of thyroid hormones in their body. It can be caused by Graves disease, thyroiditis (inflammation), and taking too much thyroid hormone.

Those with overt hypothyroidism (clear hypothyroidism with an increased TSH and a decreased T4 level) are typically treated with thyroid medications. However, people with subclinical hyperthyroidism and subclinical hypothyroidism may be followed periodically without requiring immediate treatment. The main difference between overt and subclinical hypothyroidism is that the latter category presents with normal thyroid hormone levels, but TSH levels are slightly elevated. 

Does an underactive thyroid gland cause high cholesterol?

According to the American Thyroid Association, thyroid hormones have a direct effect on the blood cholesterol level. The thyroid gland is known to produce hormones T3 and T4 that play an important role in many functions and processes in the body, including lipid metabolism in the liver. Studies have shown that low levels of thyroid hormones in the body can prevent the liver from properly processing cholesterol and eliminating excess cholesterol from the body. Hypothyroidism (underactive thyroid) is therefore linked to high LDL cholesterol, high triglycerides, and high total cholesterol levels. Even people with subclinical hypothyroidism (mildly low thyroid hormone levels) can have higher than normal LDL cholesterol (bad cholesterol). 

Animal studies have shown that increased thyroid stimulating hormone levels (TSH levels), a common finding in people with hypothyroidism, can potentially lead to high cholesterol levels.

The link between cholesterol levels and reduced thyroid function is further strengthened by the fact that 13% of people who have hypothyroidism also have hyperlipidemia (high cholesterol levels).

Whereas hypothyroidism (underactive thyroid) can lead to increased cholesterol levels, hyperthyroidism (overactive thyroid) can have the opposite effect on cholesterol levels. Specifically, hyperthyroidism can cause blood cholesterol levels to be abnormally low.  Check out “What Can Cause a Sudden Increase in Cholesterol?”