The Effect of Methimazole on Thyroid Gland Uptake of Technetium in Hyperthyroid Patients

Abstract

Introduction: The aim of this study was to investigate the effect of methimazole on Technetium-99m reabsorbing by thyroid gland , it may be possible to perform thyroid scan when the patients are on the methimazole, this can be time saving and decrease the adverse effects of discontinuing methimazole. Patients and Methods: Among all the patients with hyperthyroidism who referred to nuclear medicine ward of Shiraz University of medical sciences, 50 patients were randomly selected. we asked the patients who were on Methimazole, to discontinue the usage of all drugs (not Methimazole) and foods which are effective on thyroid gland for 1 week, after that thyroid scan was performed for these patients. In The other episode, we asked them to discontinue the usage of all drugs (also Methimazole) and foods which are effective on thyroid gland for 1 week and then thyroid scan was performed again .Revealed data was analyzed under supervision of statistical specialist with descriptive methods on SPSS. Results: 34 patients were males (68%) and other was females. Mean age of the patients was 53.5 years. (Min: 39 years and max: 75 years) Although The ROI (Region of Interest) of thyroid was increased in the patients who used methimazole before scan 398.72(SD: 191.73) than the patients who discontinued for one week 380.15 (SD: 112.49), but the difference wasn’t statistically significant. The ROI of peripheral tissue of the thyroid was decreased in the patients who used methimazole before scan 26.44(SD: 5.42) than the patients who discontinued for one week 27.0414 (SD: 5.57), but the difference wasn’t statistically significant. Discussion: In conclusion, we demonstrated that methimazole pretreatment does not interfere with either the efficacy of ROI and reabsorbing of Technetium-99m in thyroid gland and peripheral tissues. A possible limitation of this study is the number of patients in the sample.So it seems that it may be possible to perform thyroid scan when the patients are on the methimazole, this can be time saving and decrease the adverse effects of discontinuing methimazole. [GMJ. 2012;1(1):8-12]