Reverse T3 levels in affective disorders

Serum levels of 3,3',5' triidothyronine (reverse T3) were investigated in 32 patients with acute major depressive disorder. Twenty-six of these patients were also studied during a state of clinical improvement. Comparison subjects were 22 healthy controls, and 16 currently euthymic patients with histories of affective disorders (8 unipolar, 8 bipolar). The laboratory investigation included the determination of triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and thyroxin-binding globuline (TBG) levels in serum. The clinical symptoms were rated by the Comprehensive Psychopathological Rating Scale (CPRS) for depressive illness (CPRS global score), as well as the sum of 10 items (CPRS 10) and 22 items (CPRS 22) measuring depression. The patients were also divided into those having a normal or abnormal response to the dexamethasone suppression test; those having melancholia or not having melancholia; and those having primary or secondary depression. No significant difference in reverse T3 levels emerged among the patients with acute major depressive disorders, the euthymic unipolar or bipolar affective disorders, and the healthy controls. There were also no significant differences between those having an abnormal or normal DST test; those having primary or secondary depression; or those having melancholia or not having melancholia. In the group of patients with acute major depressive disorder, however, a significant increase in reverse T3 levels and a significant decrease in T3 levels, but no significant difference in T4 or TSH levels, were seen in the patients with the most pronounced clinical symptoms as measured by the CPRS. The implications of these findings are discussed.