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עמוד בית
Wed, 29.05.24

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September 2008
M. Shuvy, J. E. Arbelle, A. Grosbard and A. Katz

Background: Heart rate variability is a sensitive marker of cardiac sympathetic activity.

Objectives: To determine whether long-term hyperthyroidism induced by thyroxine suppressive therapy affects HRV[1].

Methods: Nineteen patients treated with suppressive doses of thyroxin for thyroid cancer and 19 age-matched controls were enrolled. Thyroid function tests and 1 minute HRV were performed on all subjects and the results were compared between the groups. The 1 minute HRV was analyzed during deep breathing and defined as the difference in beats/minute between the shortest and the longest heart rate interval measured by eletrocardiographic recording during six cycles of deep breathing.

Results:  One minute HRV during deep breathing was significantly lower among thyroxine-treated patients compared to healthy controls (25.6 ± 10.5 vs. 34.3 ± 12.6 beats/min, P < 0.05). There were no significant differences in mean, maximal and minimal heart rate between the groups

Conclusions: Thyroxine therapy administered for epithelial thyroid cancer resulted in subclinical hyperthyroidism and significantly decreased HRV due to autonomic dysfunction rather than basic elevated heart rate.






[1] HRV = heart rate variability


August 2006
March 2006
T. Berlin, A. Lubina, Y. Levy and Y. Shoenfeld
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