A Comparison of Pretreatment with Potassium Perchlorate and Methylthiouracil on Results of 131I Therapy

The outcome of radioiodine therapy has been studied in three groups of thyrotoxic patients: (I) 49 patients pretreated with potassium perchlorate, (II) 53 patients with no previous drug therapy, and (III) 48 patients pretreated with methylthiouracil in whom the therapeutic dose of 131I was increased by one third. No significant difference was found between the groups. The results suggest that methylthiouracil renders the thyroid gland radioresistant by a mechanism other than goitrogenesis or inhibition of thyroid hormone synthesis.