The authors assessed the mood and cognitive effects of sequential T4,
T3, and withdrawal of thyroid hormone replacement on 25 patients who had
had thyroidectomies for thyroid cancer. The patients experienced increased
sadness and anxiety when they were without medication, but not significant
difference in mood was noted between T4 and T3. The patients who
experienced increased affective symptoms when not taking medication were
more likely to have histories of affective illness or mood lability.