Lithium therapy: an unusual cause of elevated and diffuse radioactive iodine uptake.

Lithium carbonate, a widely used treatment for bipolar disorders, is associated with goiter, hypothyroidism and thyrotoxicosis. However, the effect of lithium to increase radioactive iodine uptake has received little attention, thus, making Lithium a confounding factor in the interpretation of thyroid radionuclide studies. We herein report a case of mistaken diagnosis of Graves’ disease in a euthyroid, lithium-treated goitrous patient; due to elevated radioiodine uptake of 77.6%. We conclude that lithium therapy should be considered in the etiologic diagnoses of patients with goiter and homogenously elevated radioiodine uptake. It is pertinent to recognize this phenomenon in order to prevent unwarranted treatment with radioactive iodine or thionamides.