Lithium-related thyroid changes linked to depression in bipolar

Lithium-related changes in thyroid function are clinically relevant and should be carefully monitored in the maintenance phase of bipolar disorder, researchers say. According to the authors, the results of their study of pooled data from two 18-month maintenance studies of lamotrigine and lithium monotherapy suggests that a reduction in thyroid function can exacerbate bipolar symptoms even in euthyroid patients. The retrospective post hoc analysis included 109 bipolar I patients with normal thyroid-stimulating hormone (TSH) levels at baseline who received lamotrigine (n=55), lithium (n=32), or placebo (n=22) monotherapy for a mean period of 52 weeks. By week 52, the researchers found that patients treated with lithium had a statistically significant increase in mean TSH levels from baseline (+1.0 µIU/ml) compared with those treated with lamotrigine (-0.2 µIU/ml) or placebo (+0.1 µIU/ml). Additionally, three patients taking lithium developed above normal TSH levels by week 52 (8.4, 6.5, and 7.8 µIU/ml). “This finding is consistent with the possibility that lithium-associated inhibition of thyroid function might have contributed to the development of depressive symptoms,” the researchers wrote in Acta Psychiatrica Scandinavica. Furthermore, they noted, lithium-treated patients who required an intervention for a depressive episode had significantly higher TSH levels compared with those who did not need intervention. This significant difference was not seen in other groups or in the manic episode....