News & Events

Thyroid Health and Heart Disease: What You Need to Know

March 4, 2025 | Education

by Kimberly Dorris, Executive Director

January was recognized as Thyroid Awareness Month, so perhaps it’s fitting that National Heart Month follows in February!

Organizations like the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute (NHLBI) work to raise awareness of heart disease risk factors—including high blood pressure, high cholesterol, and lifestyle choices. However, one lesser-known factor that can significantly affect heart health is thyroid hormone levels.

Whether you have hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid), keeping your thyroid levels within the normal range is essential for protecting your heart.

How Hypothyroidism Affects Heart Health

Hypothyroidism can slow down various body functions, including heart rate. Common cardiac-related symptoms include:
✅ Bradycardia (slow heart rate)
✅ Fluid retention, which can contribute to high blood pressure
✅ Hyperlipidemia (high cholesterol levels)

Because of the connection with high cholesterol, some medical organizations recommend thyroid function testing for patients with newly diagnosed hyperlipidemia. In some cases, treating the underlying hypothyroidism may help normalize cholesterol levels without the need for additional medication.

How Hyperthyroidism Affects Heart Health

For many Graves’ disease patients, a rapid heart rate (tachycardia) is often one of the first noticeable symptoms. Other potential heart-related complications include:
✅ High blood pressure
✅ Irregular heart rhythms (arrhythmias)
✅ Increased risk of heart failure

Unfortunately, some patients may initially attribute these symptoms to stress or excessive caffeine consumption, delaying diagnosis. Others may undergo cardiac testing without an immediate thyroid evaluation, leading to delayed treatment. Early thyroid function testing can help determine if the thyroid is the root cause of these cardiovascular symptoms.

Subclinical Hyperthyroidism: A Hidden Risk

Subclinical hyperthyroidism (SH) occurs when T3 and T4 levels are normal, but TSH is too low. Doctors may recommend monitoring or treatment based on:
✔️ Symptoms
✔️ Age
✔️ Bone density
✔️ Existing heart disease or cardiac risk factors

For patients with existing heart conditions, even mild thyroid overactivity can increase the risk of atrial fibrillation (AFib) and other cardiovascular issues, making treatment a priority.

Do Hyperthyroidism Treatments Affect Heart Risk?

Getting a timely diagnosis and treatment is crucial for reducing heart-related complications. But do different treatment options impact cardiovascular risk?

A 2024 study from Taiwan (1) examined the long-term cardiovascular outcomes of patients treated with:
🔹 Antithyroid drugs (ATDs)
🔹 Radioactive iodine (RAI)
🔹 Thyroid surgery (thyroidectomy)

The study found that RAI and surgery provided better cardiovascular risk reduction than antithyroid drugs. However, researchers noted that ATD-treated patients had the highest relapse rate (63.5%).

In the U.S., antibody testing is recommended before discontinuing ATDs to minimize relapse risk. (2) Some patients may also remain on low-dose ATDs for an extended period.

Until a study controls for proper ATD management, it will be difficult to directly compare treatment risks. However, regardless of treatment choice, the most important thing is to closely monitor thyroid levels and follow your doctor’s recommendations.

Takeaways for Protecting Your Heart and Thyroid Health

✔️ Stay on top of lab testing: Regular thyroid function tests can help identify imbalances early.
✔️ Follow medication guidelines: Whether you take thyroid hormone replacement (for hypothyroidism) or antithyroid drugs (for hyperthyroidism), consistency is key.
✔️ Monitor changes in symptoms: If you notice new or worsening symptoms such as palpitations, changes in heart rate, tremors, or unexplained fatigue, contact your doctor.
✔️ Maintain a heart-healthy lifestyle: Regular exercise, a balanced diet, and stress management all contribute to better overall heart health.

By taking these steps, you can help reduce your risk of cardiovascular complications related to thyroid disease.

News & Events

Recent Posts

Archives

Categories