A case of suspected lithium-induced hyperthyroidism

Lithium is widely used as a mood stabilizer in psychiatry. As a medication, it has a very narrow therapeutic index and carries the risk of numerous adverse effects, including thyroid endocrinopathies. While hypothyroidism caused by lithium is well-documented in the medical literature, incidences of lithium-induced hyperthyroidism have been elusive and etiologically difficult to define. Herein we present the case of a 32-year-old woman with multiple psychiatric comorbidities and no history of thyroid disease who developed hyperthyroidism within one month of starting lithium therapy. This case report is one of the few in the literature documenting this rare phenomenon where the initiation of lithium therapy closely precedes the onset of thyrotoxicosis. We also discuss the potential pathogenesis of lithium-induced hyperthyroidism, with special emphasis on silent thyroiditis as the most likely cause of our patient's presentation.