Manage Hyperthyroidism to Prevent Cardiac Complications

An overactive thyroid—the condition known as hyperthyroidism—can cause several health problems; abnormal heart rhythms are among the more serious.


The thyroid gland produces a hormone that can affect your heart rate as well as your nervous system and other aspects of your health.

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A diagnosis of hyperthyroidism (overactive thyroid) means having to be “hyper aware” of the potential health complications stemming from this condition. Your little thyroid gland affects almost every aspect of your health, including your metabolism and nervous system.

One other area in particular that is vulnerable to untreated hyperthyroidism is your heart, which can be affected in a number of ways. One significant effect, experts say, can be an increased heart rate, which can result in fatigue of the heart muscle and heart failure. If untreated for many years, damage to the heart muscle can be permenant. It also can put patients at risk of developing arrhythmias (irregular heartbeats) or atrial fibrillation (afib), in which the heart’s upper chambers stop beating in a coordinated manner with the lower chambers and instead beat chaotically.

If, however, thyroid disease is diagnosed and treated in a timely manner, experts say, the effects of the condition are reversible.

Understand Thyroid Function

Your thyroid is located in your neck. It’s a relatively small gland, and it produces two types of thyroid hormone. Thyroid hormones affect just about every system and every cell in the body.

One of the problems of an overactive thyroid­—one that produces too much hormone—is that it causes your system to speed up. For example, hyperthyroidism can affect your metabolism and how fast your body burns calories. It can also affect how fast food moves through your digestive system. Usually, people with hyperthyroidism lose weight, but it can lead to weight gain in some cases.

Too much thyroid hormone can also affect your nervous system, body temperature, and muscle strength. It plays a role in how fast new cells are produced to replace dead ones, too.

A healthy thyroid helps keep your heart beating in a steady rhythm at a normal rate. But an overactive thyroid can cause palpitations and an accelerated heart rate.

Diagnosis and Treatment

Diagnosing hyperthyroidism usually starts by having symptoms evaluated. You may notice a rapid heartbeat (tachycardia), sudden weight loss, a tremor, nervousness, fatigue, difficulty sleeping, and brittle hair.

A physical exam and review of your symptms and medical history are part of the diagnosis. But a blood test measuring thyroid hormone in the system can confirm hyperthyroidism. Other tests can help determine why your thyroid is overactive.

Treatment for hyperthyroidism may include medications that help reduce hormone production. Treatment with radioactive iodine can help shrink the thyroid and control symptoms. You may also be prescribed beta blockers to help control your heart rate. Surgery to remove most of the thyroid gland is done in some, but not many, cases.

The treatment usually depends on the cause of the hyperthyroidism. In some cases, treatment may involve a combination of options—medications for a period of time followed by surgery, for example, or radiation therapy.

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Jay Roland

Jay Roland has been executive editor of Massachusetts General Hospital’s Mind, Mood & Memory since 2017. Previously, he held the same position with Cleveland Clinic’s Heart Advisor, since 2007. In … Read More

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