Which mood stabilizer is most likely to decrease thyroid function?

Lithium is well-documented for its potential effects on thyroid function. It can induce hypothyroidism by interfering with the synthesis and release of thyroid hormones. This is particularly significant for individuals who may already have a predisposition to thyroid dysfunction or for those who have underlying thyroid issues. Regular monitoring of thyroid function is essential in patients receiving lithium therapy, as the drug's effects on the thyroid can lead to clinical hypothyroidism, which may require treatment with thyroid hormone replacement.

In contrast, carbamazepine, valproic acid, and chlorpromazine do not have the same notable impact on thyroid function as lithium. While they may have other side effects, their effects on the thyroid are minimal compared to lithium's pronounced influence. Thus, when considering the potential for decreasing thyroid function, lithium stands out as the mood stabilizer most likely to cause this issue.