A

The prospective study comparing hypothermic (≈26 °C) and normothermic (≈35 °C) cardiopulmonary bypass found identical postoperative thyroid‐hormone patterns in both groups—triiodothyronine and thyroxine fell, reverse T3 rose, and TSH remained unchanged—indicating development of euthyroid sick syndrome irrespective of bypass temperature. The authors concluded that normothermic CPB “does not prevent the development of the ‘euthyroid sick syndrome’ during and after CPB,” i.e., temperature had no effect [Thrush 1995, PMID 7497757].