LITHIUM TREATMENT IN AMIODARONE-INDUCED THYROTOXICOSIS

PURPOSE: Amiodarone hydrochloride is an iodine-rich drug effective in the control of various tachyarrhythmias. It is known to cause refracto ry thyrotoxicosis, which usually does not respond to regular antithyro id drugs. Lithium bicarbonate is a medication used to treat psychiatri c disorders; it also influences thyroid production and release of horm ones. We tried it in combination with propylthiouracil (PTU) for the t reatment of amiodarone-induced thyrotoxicosis. PATIENTS AND METHODS: T wenty-one patients were studied. The first group (n = 5) was treated b y amiodarone withdrawal only. The second group (n = 7) received PTU (3 00 to 600 mg), and the third (n = 9) PTU (300 mg) and lithium (900 to 1350 mg) daily. Patient selection was not randomized. The PTU + lithiu m group had more severe symptoms and signs of thyrotoxicosis, as well as thyroxine levels at least 50% above the upper limit of normal. They also had been on a longer course of amiodarone treatment (34.3 +/- 11 .9 months) than the PTU-only (11.4 +/- 7.5) and the no-treatment (7.8 +/- 4.2) groups. RESULTS: While there was no difference between the fi rst two groups in time until recovery (10.6 +/- 4.0 versus 11.6 +/- 0. 5 weeks, respectively), the group receiving lithium normalized their t hyroid function tests in only 4.3 +/- 0.5 weeks (P < 0.01 versus both other groups). T-3 levels normalized even earlier-by 3 weeks of lithiu m treatment. No adverse effects of lithium were encountered, and the m edication was stopped 4 to 6 weeks after achieving a normal clinical a nd biochemical state. CONCLUSIONS: We conclude that lithium is a usefu l and safe medication for treatment of iodine-induced thyrotoxicosis c aused by amiodarone. We would reserve this treatment for severe cases only. Further studies are needed to find out whether in patients with this troublesome complication lithium therapy could permit continuatio n of amiodarone treatment. (C) 1997 by Excerpta Medica, Inc.