Lithium carbonate plus ¹³¹I in the treatment of Graves’ hyperthyroidism

Abstract

Aims: Effectiveness of radioiodine for Graves’ hyperthyroidism (GD) depends on its intrathyroidal persistence, which could be enhanced by lithium by blocking the release of organic iodine and thyroid hormone from the thyroid gland. The present aim focused on the effect of the addition of lithium carbonate to 131 I therapy in patients with GD. Methods: 100 consecutive patients with GD were randomly assigned to two groups: group (A) patients treated with 131 I and group (B) patients treated with 131 I plus lithium carbonate . Patients in B group were treated with a dose of 0.5 g per day (2 × 0.25 g) of lithium carbonate for half a month before and after the administration of 131 I. Thyroid weight was estimated by ultrasonography and careful palpation of the thyroid. Radiation absorbed dose rate in the front of the neck was measured on days 1530 and 45 after the administration of 131 I . Serum concentrations of thyroidstimu lation hormone (TSH), fee tri-iodothyrosine (T3) and free thyroxine (T4) were tested on days 30, 45, 90, 180 before and after treatment. Results: After RIT, radiation absorbed dose rate in the front of neck gradually decreased as time went on (p < 0.01), all of which were significantly higher in B group than those in A group (p < 0.01). Of all different time periods before and after treatment, the mean serum TSH of the two groups was below the normal range without significant difference (p > 0.05), free T3 and free T4 values in both groups rose significantly one month after treatment (all p < 0.01) , then decreased into the normal ranges. Over 30 d of treatment, the values in B group patients were much lower than those in A group (all p < 0.01). No significance was found in other time periods (all p > 0.05). Cure rate of hyperthyr oidism was achieved in 36 of the 50 patie nts (72%) treated with 131 I alone and in 38 of the 50 patients (76%) treated with 131 I plus lithium. Conclusion: We suggest that for patients withdrawing of ATD and those with short effective half-time, as well as those intolerant or invalid, the short term addition of lithium to 131 I allows for a better control of thyrotoxia and the completeness of treatment.