Lithium Treatment and Thyroid Disorders

Abstract

Lithium is a widely used and effective long term therapy for bipolar disorders. Its use is associated with thyroid abnormalities commonly reported in the literature. Lithium affects normal functioning through multiple mechanisms. It inhibits synthesis and release of thyroid hormones and may reduce the thyroid iodine uptake. Lithium can induce thyrocyte proliferation by two mechanisms: the inhibition of the TSH/cAMP pathway and more recently identified is the activation of the Wnt/beta-catenin signaling pathway. Lithium finally affects different parameters of the immune system. Goitre is the most frequent disorder noted in up to 55% of patients on lithium therapy. Hypothyroidism is observed in up to 52%. Lithium induced hyperthyroidism is a less common and controversial finding. Lithium increases thyroid autoimmunity if present before therapy. Patients taking lithium should not stop the drug if thyroid dysfunction develops. Practicing clinicians managing lithium treated patients should be aware of these potential disorders. Adequate monitoring is essential in order to identify them and thus institute early and appropriate treatment