The Link Between Thyroid Disease and Cholesterol

Thyroid disease and cholesterol levels are closely related.

Interactions between these conditions include:

• High cholesterol (hyperlipidemia) is linked to hypothyroidism (underactive thyroid).
• A sudden drop in cholesterol can occur with hyperthyroidism (overactive thyroid).
• Treating thyroid disease can correct cholesterol levels.
• Cholesterol drugs can affect thyroid disease and its treatments.

This article explains why thyroid disease and high cholesterol are linked, the potential problems, and how to manage both conditions at once.

Why Thyroid and Cholesterol Are Linked

Thyroid hormones have several jobs, including regulating your body's energy.

These hormones also control how your body uses cholesterol and other lipids (fats) and help your liver produce fatty acids, which store energy for you to use later.

When thyroid hormones are not at the right levels, these processes can be affected. Getting thyroid hormones in balance helps regulate cholesterol.

Low Thyroid & High Cholesterol

Thyroid-stimulating hormone (TSH) can be measured with a blood test. Made by a small gland in the brain called the pituitary gland, TSH stimulates your thyroid gland to release thyroid hormones.

High TSH levels usually mean you have an underactive thyroid.

Symptoms include:

• Fatigue
• Weight gain
• Slow heart rate

Studies show that people with high TSH levels have much higher total cholesterol and LDL (bad cholesterol) levels than people with normal TSH levels.

Health Risks

Untreated hypothyroidism is linked to serious health risks.

These include:

• Heart disease
• Stroke
• Blood clots
• Chronic kidney disease

High cholesterol further raises the risk of blood clots, heart disease, and stroke.

High Thyroid & Low Cholesterol

Excessively low cholesterol can cause health problems. Sometimes, a sudden drop in cholesterol levels can be a sign of an overactive thyroid.

If you have hyperthyroidism, your thyroid produces too much T3 and T4, which are thyroid hormones.

High levels of these hormones speed up certain processes in your body, leading to:

• Anxiety
• Sudden weight loss
• Rapid heartbeat

Graves' disease is an autoimmune condition that causes hyperthyroidism. It sometimes involves an eye disease called orbitopathy. Increased levels of LDL and total cholesterol are risk factors for orbitopathy.

Health Risks

Without treatment, hyperthyroidism can lead to:

• Orbitopathy
• Osteoporosis (brittle bones)
• Abnormal heart rhythm
• Stroke or heart attack
• A potentially life-threatening condition called thyroid storm

Low cholesterol is associated with an increased risk of:

• Some cancers
• Mood disorders
• Heart disease

Both conditions are associated with heart disease, possibly compounding the risk.

Thyroid Treatment and Cholesterol

You can get effective treatment for underactive or overactive thyroid. Adequate thyroid treatment helps manage your thyroid hormones and may impact your cholesterol as well.

Underactive Thyroid Treatment

Hypothyroidism is usually treated with the drug Synthroid (levothyroxine), a synthetic form of the hormone T4. This drug often improves thyroid levels and cholesterol levels.

A large study of people with hypothyroidism and high cholesterol showed that treating the thyroid problem corrected cholesterol levels 60% of the time.

Since levothyroxine doesn't always get cholesterol levels in the ideal range, additional medical treatments may be needed.

These include cholesterol-lowering medications such as:

• Statins, such as Lipitor (atorvastatin) or Crestor (rosuvastatin)
• Zetia (ezetimibe)
• PCSK9 inhibitors, such as Repatha (evolocumab) and Praluent (alirocumab)

Overactive Thyroid Treatment

Treating hyperthyroidism can help raise low cholesterol levels.

Possible treatments include:

• Antithyroid drugs: Medications that lower your thyroid's hormone production
• Radioiodine therapy: Comes in capsule or liquid form; slowly destroys thyroid cells that produce hormones
• Surgery: All or part of the thyroid is removed

If your entire thyroid gland is removed, you'll need to take thyroid replacement hormones (such as levothyroxine) for the rest of your life. This is sometimes the case with partial removal and radioiodine therapy as well.

Cholesterol Treatments and Thyroid Disease

Cholesterol treatments can affect thyroid disease and treatment in several ways.

Absorption

Drugs classified as bile acid resins may prevent your body from absorbing levothyroxine.

They're prescribed for hyperthyroidism and include:

• Questran (cholestyramine)
• Colestid (colestipol)
• Welchol (colesevelam)

You should take these drugs at least four hours after taking levothyroxine to avoid this effect.

Muscle Pain

Muscle pain can be a side effect of statin medications. If you have hypothyroidism, you may be likely to experience this side effect.

Hyperthyroidism Symptoms

Niacin is a treatment that is sometimes recommended for increasing HDL ("good cholesterol") levels.

Its side effects, such as flushing, can closely mimic the symptoms of hyperthyroidism. That might make you think your thyroid treatments aren't working properly.

Thyroid Eye Disease

A 2018 study found that treating high cholesterol with statin medications reduced the risk of Grave's orbitopathy.

Lifestyle Changes for Both Conditions

Lifestyle changes can help you manage cholesterol and thyroid problems.

Your healthcare provider may recommend the following:

• Diet: An anti-inflammatory diet may lower inflammation from autoimmune thyroid disease and lower cholesterol.
• Weight loss: If you are overweight, sometimes weight loss can help can lower LDL cholesterol levels and improve thyroid health.
• Exercise: Regular exercise can improve energy levels if you have hypothyroidism, and may raise your level of good cholesterol.
• Quitting smoking: Smoking harms the thyroid and increases the risk of health complications. It also adds to the cholesterol-related risk of heart disease and stroke.

Summary

Thyroid hormones are associated with cholesterol levels. If your cholesterol is high or drops suddenly, you might need to have your thyroid checked.

Thyroid treatments may help you reduce your risk of complications such as heart attack and stroke, and they may also help you manage cholesterol.

If you are taking a cholesterol-lowering medication, know that it can affect your thyroid disease and treatments.

A Word From Verywell

Cholesterol levels can be affected by thyroid disease, and sometimes your cholesterol level can change as your thyroid condition changes and with your thyroid treatment. In addition to medication, lifestyle factors, such as diet and exercise, can have an impact as well.