Hyperthyroxinemia in major affective disorders.

Ninety-nine patients fulfilling DSM-III criteria for primary major affective disorder, either bipolar or unipolar, were studied. A 12% prevalence of elevated thyroxine levels was found. Three of the 12 hyperthyroxinemia patients also had elevated free thyroxine index. No statistically significant difference in response to antidepressant treatment was observed between the hyperthyroxinemia group and the normal serum thyroxine group.