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T3 and Heart



The hormone triiodothyronine (T3) is essential for maturation of sarcolemmal calcium channels, myosin, actin,
and troponin. 


Hypothyroid rats demonstrate reduced numbers of Beta-receptors, as well as a reduction in stimulatory
secondary messenger protein density with an increase in inhibitory secondary messenger protein density.


T3 is mostly produced by monodeiodination of thyroxine. This process is inhibited by surgery, hypothermia,catecholamines, propranolol, and amiodarone.
Thus, postoperative T3 levels are reduced.



In randomized, double-blind, placebo- controlled study by Bettendorf et al.230 examined 40 children undergoing both simple and complex cardiac surgery. Results demonstrated that the group allocated to receive T3 had better myocardial function with a decreased duration of ICU stay. T3 provides improved contractility without any associated increase in oxygen consumption. In addition, the Bettendorf group demonstrated no delay in recovery of thyroid function secondary to exogenous administration.

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