Use of Lithium in Hyperthyroidism Secondary to Graves' Disease: A Case Report

BACKGROUND The therapeutic approach to Graves' disease (GD) comprises thionamides, radioiodine ablation, or surgery as first-line therapy, and cholestyramine and oral iodine as second-line therapies. The role of lithium (Li) in GD as a primary or adjunctive therapy remains contentious. We present a case of GD managed by Li therapy with oral iodine solution. CASE REPORT A 26-year-old man, admitted with acute blast crisis secondary to chronic myeloid leukemia (CML), reported palpitations, 40-lb weight loss, heat intolerance, and fatigue. An examination revealed sinus tachycardia, elevated body temperature, and thyromegaly. Laboratory evaluation confirmed hyperthyroidism (TSH <0.005 mcIU/l, FT4 5.57 ng/dl, TT3 629 ng/dl) secondary to GD (TRAb >40 IU/l, TSIg 178%). Thionamides and surgery were contraindicated due to pancytopenia from a blast crisis. Inability to maintain post-radiation precautions precluded use of RAI. Cholestyramine was attempted and discontinued due to nausea. We introduced oral Li carbonate with oral iodine, which the patient tolerated. Thyroid functions improved with therapy (TSH 0.007 mcIU/l, FT4 0.82 ng/dl, TT3 122 ng/dl) with stable Li level (0.5-0.8 mmol/l). CONCLUSIONS Li inhibits iodine uptake through interference with sodium-iodide symporter and tyrosine iodination, thyroglobulin structure changes, peripheral deiodinase blockage, and preventing TSH and TSIg stimulation. Our case shows that a low therapeutic level of Li, in combination with oral iodine, can suppress thyroid overactivity without adverse effects. We suggest that low-dose Li carbonate is a safe and effective adjunctive antithyroid medication to be considered if primary therapies for hyperthyroidism are unavailable.