Why does too much thyroid hormone make your heart race?
Effects of thyroid hormone on cardiac beta-adrenergic responsiveness in conscious baboons.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Giving extra thyroid hormone to baboons made their hearts pump harder at rest and increased the number of heart receptors that respond to adrenaline-like signals, but didn't make those receptors more sensitive.
Surprising Findings
Despite a 100%+ increase in beta-adrenergic receptors, the heart’s percent response to adrenaline-like drugs (dobutamine/terbutaline) remained unchanged.
Common belief is that more receptors = stronger response. This study shows quantity doesn’t equal sensitivity—contradicting assumptions about how hormone excess drives cardiac symptoms.
Practical Takeaways
If you have hyperthyroidism and feel your heart racing, it may be due to more receptors—not because each one is overreacting.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Giving extra thyroid hormone to baboons made their hearts pump harder at rest and increased the number of heart receptors that respond to adrenaline-like signals, but didn't make those receptors more sensitive.
Surprising Findings
Despite a 100%+ increase in beta-adrenergic receptors, the heart’s percent response to adrenaline-like drugs (dobutamine/terbutaline) remained unchanged.
Common belief is that more receptors = stronger response. This study shows quantity doesn’t equal sensitivity—contradicting assumptions about how hormone excess drives cardiac symptoms.
Practical Takeaways
If you have hyperthyroidism and feel your heart racing, it may be due to more receptors—not because each one is overreacting.
Publication
Journal
Circulation
Year
1997
Authors
B. Hoit, Saeb F. Khoury, Y. Shao, Marjorie Gabel, S. B. Liggett, Richard A. Walsh
Related Content
Claims (4)
When your body has too much thyroid hormone, it makes your heart beat faster and makes you sweat more—even when you're not exercising or stressed out.
Even though baboons with too much thyroid hormone have more heart receptors that respond to adrenaline, their hearts don’t beat stronger or relax faster when given drugs that stimulate those receptors.
Giving thyroid hormone to baboons for four weeks makes their hearts pump more strongly and relax faster while at rest, without changing their heart rate — like giving the heart a boost in efficiency.
When baboons are given thyroid hormone, their bodies develop many more of a certain type of receptor that helps respond to stress and energy signals—especially the beta-2 kind—making them much more sensitive to these signals.