The Study
Effects of thyroid hormone on cardiac beta-adrenergic responsiveness in conscious baboons.
This study watched how a monkey's heart reacted after giving it extra thyroid hormone. It found that the heart beat stronger and had more receptors, but it didn't prove the hormone caused those changes — it just showed they happened together.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
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.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 513 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this suggests that in humans with hyperthyroidism, the fast heartbeat and sweating may come from more receptors being present, not from each receptor working harder.
- 2Resting heart pumping strength (dP/dtmax) went up from 2318 to 3073 mm Hg/s.
- 3Heart relaxation time (tau) dropped from 28.2 to 24.0 ms.
- 4Beta-adrenergic receptors increased over 100%, especially beta-2 (from 5.9 to 20.6 fmol/mg).
- 5But when given adrenaline-like drugs, the heart's response as a percentage didn't change.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
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.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.