The effect of combination therapy with propylthiouracil and cholestyramine in the treatment of Graves' hyperthyroidism

Summary Objective The study aims to evaluate the efficacy of combination therapy with propylthiouracil (PTU) and cholestyramine in the treatment of Graves’ hyperthyroidism. Background Thyroxine (T4) is metabolized mainly in the liver by conjugation to glucuronides and sulphates that enter the enterohepatic circulation. Thyrotoxic patients have an abnormal increase in thyroid hormone in their enterohepatic circulation. Previous studies on combination therapy with methimazole and cholestyramine for Graves’ hyperthyroidism have shown it to be an effective adjunctive treatment. In this study, we examined the efficacy of combination therapy with PTU and cholestyramine in the treatment of Graves’ hyperthyroidism. Methods Thirty patients with newly diagnosed Graves’ hyperthyroidism were randomly divided into two groups: group I (n = 15) received PTU 100 mg twice a day, propranolol 40 mg twice a day and cholestyramine 4 g twice a day for 4 weeks; group II (n = 15) received PTU 100 mg twice a day and propranolol 40 mg twice a day for 4 weeks. The therapeutic efficacy was determined by serum total triiodothyronine (TT3), free thyroxine (FT4) and TRAb levels at baseline, and at the end of 2 and 4 weeks during the study period. Results There was no significant difference in baseline thyroid function parameters. At the end of 2 and 4 weeks of the study period, serum TT3 and FT4 levels of group I were significantly lower than those of group II. No significant differences in the TRAb level were found between the two groups. Conclusion Cholestyramine contributed to a more rapid and complete decline in thyroid hormone levels in patients with Graves’ hyperthyroidism. It was thus proved to be an effective and well-tolerated adjunctive therapy.