Hyperthyroidism and arrhythmia: what to know

Excess thyroid hormone can make the heart respond more strongly to normal signals. You may notice pounding, fluttering, skipped beats, a racing pulse, breathlessness, tiredness or reduced exercise tolerance. An irregular rhythm such as atrial fibrillation is one possible effect, but palpitations can also have other causes.

A diagnosis is based on your symptoms, pulse, an electrocardiogram and thyroid blood tests. A clinician may also check medicines, caffeine, dehydration and other heart conditions. Hyperthyroidism is described on the condition page.

Arrange a prompt appointment if new palpitations keep returning, last more than a brief episode, or occur with a known thyroid problem. Record when they begin, how long they last, whether the rhythm feels regular, and any breathlessness or dizziness. Take prescribed thyroid treatment exactly as directed and do not change the dose without advice.

Until assessed, rest during an episode, drink fluids if you can, and avoid stimulants such as energy drinks. A clinician may treat the thyroid overactivity and use a heart-rate medicine when appropriate.

Call emergency services for palpitations with chest pressure or pain, severe breathlessness, fainting, new confusion, marked weakness, or a sustained very fast or irregular heartbeat. Seek same-day medical advice for repeated episodes, worsening symptoms, or dizziness even if they settle. Do not drive yourself if you feel faint.

Could my thyroid activity be affecting my heart rhythm? Do I need an electrocardiogram or monitoring? Which symptoms should prompt emergency care? How will treatment and follow-up blood tests be coordinated?