About 1% of the time, high blood pressure (hypertension) is caused by thyroid disorders, such as hyperthyroidism. Increased thyroid hormone in your bloodstream can cause your heart to pump more blood, which may stiffen your arteries and raise your blood pressure.

Hyperthyroidism happens when you have higher than usual levels of thyroid hormone. It affects about 1 out of 100 people in the United States over the age of 12 years. It can cause symptoms such as:

  • a rapid heartbeat
  • persistent fatigue
  • weight loss
  • irritability
  • trouble sleeping
  • poor heat tolerance

More than a quarter of the world’s population has high blood pressure (hypertension). Hyperthyroidism is a well-established but relatively rare cause of high blood pressure.

Read on to learn more about the link between hyperthyroidism and high blood pressure.

In about 10% of people with high blood pressure, the cause is secondary. This means that high blood pressure is caused by an underlying health condition. Approximately 1% of the time, the cause of high blood pressure is due to thyroid disorders.

Both hypothyroidism and hyperthyroidism can cause high blood pressure. Hypothyroidism is when your body doesn’t produce enough thyroid hormone.

What is thyroid hormone and what does it do?

Thyroid hormone is the collective name for two hormones that your thyroid gland produces: thyroxine (T4) and triiodothyronine (T3). These hormones play a role in regulating your metabolism and determining how your body uses energy. Thyroid hormone acts on every cell in your body.

T3 is the active form of thyroid hormone, while T4 is largely inactive. About 90% of the thyroid hormone your thyroid gland produces is T4, which can be converted to T3 in your liver, kidneys, or muscles.

Effect of hyperthyroidism on blood pressure

It’s well established that hyperthyroidism can increase your risk of high blood pressure. Some research suggests that between 36–65% of people with hyperthyroidism have high blood pressure.

In addition to symptoms like a rapid heartbeat and unintentional weight loss, increased thyroid hormone in your bloodstream can also increase your cardiac output — the amount of blood your heart pumps each minute. Additionally, it can increase the stiffness of your arteries by reducing their ability to expand.

Increased arterial stiffness combined with an increased cardiac output may lead to more blood being pumped through a smaller space, which can raise blood pressure.

Hyperthyroidism and other cardiovascular diseases

Hyperthyroidism that’s left untreated for long periods can also increase the risk of other types of cardiovascular disease. It’s associated with a higher risk of:

High blood pressure is considered to be 140/90 millimeters of mercury (mm Hg) or higher.

Your doctor may suspect that you have secondary high blood pressure if you don’t have risk factors such as obesity or inactivity, and you have typical symptoms of hyperthyroidism such as a fast heart rate or persistent fatigue.

High blood pressure can be the initial sign for at least 15 types of hormonal imbalances, including hyperthyroidism and hypothyroidism.

Your doctor can find out if your thyroid hormones are contributing to your high blood pressure by ordering a blood test to measure your levels of:

Research indicates that TSH tests can identify thyroid disorders in about 98% of cases and correctly rule out a thyroid disorder in about 92%. Most insurance plans typically cover these tests.

Importance of blood pressure management

High blood pressure can cause problems throughout your body and has been linked to an increased risk of:

Treatment of high blood pressure due to hyperthyroidism often involves correcting the underlying thyroid issue. Typical treatments for high thyroid hormone levels include:

  • medications called thioamides to stop the thyroid from producing excess hormones
  • radioactive iodine treatment to destroy cells that produce thyroid hormone
  • surgery to remove all or part of your thyroid gland

For high blood pressure, adopting healthy lifestyle habits in addition to hyperthyroidism treatment may help keep your blood pressure in a healthy range. These lifestyle changes include:

  • getting regular exercise
  • achieving or maintaining a healthy body weight
  • eating a balanced, nutritious diet that prioritizes whole foods
  • quitting or avoiding smoking
  • managing your stress levels in a healthy way

Learn more about lifestyle habits for lowering blood pressure.

Hyperthyroidism is often treatable, which can help reverse complications such as high blood pressure.

Graves’ disease is the most common cause of hyperthyroidism. It’s an autoimmune disease where your immune system attacks healthy cells in your thyroid. Graves’ disease tends to have a good outlook due to high success rates of treatment.

Without proper treatment, hyperthyroidism can get worse over time. This can cause more severe symptoms and serious complications such as:

Hyperthyroidism is when your thyroid hormone levels are higher than they should be. This can increase your cardiac output and stiffen your arteries, which can raise your risk of high blood pressure.

Hyperthyroidism is often overlooked as a contributing factor for high blood pressure since it’s a relatively rare underlying cause. Your doctor may suspect hyperthyroidism if you have characteristic symptoms such as a fast heart rate, fatigue, and weight loss. A blood test can determine whether you have hyperthyroidism.

Hyperthyroidism treatments include medication, iodine treatment, or surgery. Adopting healthy lifestyle habits may help keep your blood pressure in a healthy range when combined with treatment for hyperthyroidism.