Lithium carbonate in the treatment of thyrotoxicosis. A controlled trial

Of 24 patients with newly diagnosed thyrotoxicosis, 13 were randomly selected for treatment with methimazole 40 mg per day, and 11 for treatment with lithium carbonate in such doses that the serum lithium lay between 0-5 and 1-3 meq. per litre. The lithium treatment brought about a fall in serum-thyroxine iodine (T4I) of 27.0%, and in the free-thyroxine index (F.T.I.) of 38.1% after 10 days. A comparison of the two patient groups with regard to the fall in F.T.I. after 3 and 10 days showed no statistically significant difference; similarly the calculated confidence limits appeared to exclude any difference of clinical importance. 8 of the 11 patients subjected to lithium treatment had side-effects, so that the general condition, which was already affected by the hyperthyroidism, was worsened. It is concluded that lithium cannot be considered superior to thiocarbamides for the rapid control of thyrotoxicosis.