Clinical research on radioiodine addition of low-doses of lithium carbonate in short-term treatment of Graves hyperthyroidism

Objective: To explore the effect of lithium carbonate plus ¹³¹I in the treatment of Graves hyperthyroidism. Methods: One hundred patients with Graves hyperthyroidism were enrolled in this study. All of them were randomly divided in to 2 groups: group Ⅰ with 50 patients treated with ¹³¹I and group Ⅱ with 50 patients treated with lithium carbonate plus ¹³¹I. Patients in group Ⅱ were treated with a dose of 0.5 g per day (2×0.25 g) of lithium carbonate for 15 days before and after the administration of ¹³¹I. Thyroid weight was estimated by ultrasonography and careful palpation of the thyroid before treatment, and no significance were found between this two groups. Radiation absorbed dose rate in the front of neck was measured respectively 15, 30 and 45 d after the administration of ¹³¹I. Serum concentrations of TSH, free triiodothyrosine (fT₃) and free thyroxine (fT₄) were tested respectively before and 30, 45, 90, 180 days after administration of ¹³¹I. Results: The radiation absorbed dose rate in the front of neck were decreased gradually as time went on after ¹³¹I therapy in each group. In general, the difference of radiation absorbed dose rate among different monitor term were significant (H=132.46, and 132.47, all P<0.01) in same group. The difference of radiation absorbed dose rate between each other at 15, 30 and 45 d were significant (t=88.51, 113.7, 59.42 in group Ⅰ, and 83.44, 112.76, 70.18 in group Ⅱ, all P<0.01), all of which in same monitor term were significantly higher in group Ⅱ than those in group Ⅰ (t=8.81, 15.18, 10.10, all P<0.01). The mean serum TSH of each group before and all different time periods after treatment were below the normal range(0.55∼4.78 mIU/L) without significant difference (F=1.23, P>0.05). In general, the differences of fT₃ and fT₄ values in all groups were significant (F_fT3=9.65, F_fT4=22.45, all P<0.01) before and after treatment. The fT₃ and fT₄ values in both groups rose significantly 30 days after therapy (t_fT3=5.23, t_fT4=10.14 in group Ⅰ, t_fT3=5.12, t_fT4=9.98 in group Ⅱ, all P<0.01), then decreased gradually to the normal ranges. The fT₃ and fT₄ values in group Ⅱ were much lower than those in group Ⅰ (t_fT3=8.22, t_fT4=19.18, all P<0.01) 30 days after therapy, no significance were found in other time periods. Cure rate of hyperthyroidism was achieved in 36 of the 50 patients (72%) in group Ⅰ and in 38 of the 50 patients (76%) in group Ⅱ without significant difference. There were no significant differences in curative effect of the two groups (χ²=0.21, P>0.05). Conclusion: 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 ¹³¹I allows for a better control of thyrotoxia and the completeness of treatment. But there have not been observed that lithium carbonate plus ¹³¹I can improve the long term cure rate of Graves hyperthyroidism. (authors)