Harvard Heart Letter

Thyroid hormone: How it affects your heart

Located at the base of the throat, the butterfly-shaped thyroid gland releases hormones that affect every organ in the body—especially the heart. Too little thyroid hormone (hypothyroidism) slows the heart rate and may boost blood pressure and cholesterol levels. Too much thyroid hormone (hyperthyroidism) can cause the heart to beat harder and faster and may trigger abnormal heart rhythms and high blood pressure. A simple blood test can diagnose thyroid problems, and treatment may improve heart-related problems.
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