ABSTRACT
Lithium has been established as a drug useful for the treatment of manic depressive disorder. It is now well recognized that long-term administration of this drug is associated with various antithyroid effects such as goiter, and subclinical and overt hypothyroidism. However, it has been associated less commonly with thyrotoxicosis. Recently we experienced a case of thyroitoxicosis during lithium therapy. A 24-year-old man treated with lithium carbonate 900 mg-1,200 mg/day for manic-depressive illness for four weeks. He then complained of nervousness, palpitation, tremor, heat intolerance, and sweating. Neck pain was not noted. At that time the results of thyroid function test were consistent with hyperthyroidism: T3 568.8 ng/dL, TSH 0.01 mU/mL, FT4 6.0 ng/dL, but 24 hr radioiodine uptake was 0.3%. We suspected this case as lithium induced thyrotoxicosis and discontinued lithium administration. After discontinuation of lithium thyrotoxic symptoms were subsided. One month later, thyroid hormon levels became normalized: T 100.2 ng/dL, TSH 0.06 mU/mL, FT4 0.97 ng/dL and 24hr radioiodine uptake was 16%. We report this case with review of literatures.