Differences in thyroid function between bipolar manic and mixed states

Background: High rales of thyroid axis abnormalities have been reported in most studies of patients with rapid-cycling bipolar disorder. Mixed states share similarities with rapid-cycling, including close temporal occurrence of manic and depressive symptoms, predominance in women, poor outcome, and less robust response to lithium compared with pure mania: however, thyroid axis abnormalities have not been well studied in mixed mania. Methods: To test the hypothesis that mixed states are associated with a higher prevalence of hypothyroidism than pure mama, immunorcactive triiodothyronine (T 3), thyroxine (T 4), and thyroid-stimulating hormone (TSH) concentrations were determined from serum obtained at the time of admission in 37 consecutive patients with DSM-HI-R bipolar disorder, manic or mixed. Results: The mean TSH concentration was significantly higher, and the mean T 4 concentration was significantly lower in patients with mixed mania compared with pure mania. There were no significant differences in T 3 concentration or in previous lithium exposure. Conclusions: These findings suggest thyroid axis dysfunction is more common in bipolar mixed than in bipolar manic patients.