Predictors of time to remission and treatment failure in patients with Graves' disease treated with propylthiouracil.

PURPOSE Propylthiouracil is one of the thionamides used in the treatment of Graves' disease. The drug has serious side effects and long-term treatment might be needed to achieve remission. We designed this study to evaluate the clinical and thyroid Doppler characteristics that might predict time to remission and treatment failure in propylthiouracil treated Graves' patients. METHODS 26 patients, among 134 presenting to our university hospital outpatient clinic between Feb -July 2007 and with first time diagnosis of clinical thyroid dysfunction, were clinically and ultasonographically diagnosed with Graves' disease. Doppler parameters, serum thyrotropin, free thyroxine and free triiodothyronine were measured at the beginning of the study and thyroid studies were repeated every 4 weeks until remission. Propylthiouracil 300 mg/day was started for each patient at the time of diagnosis and doses were titrated according to repeat thyroid studies. Patients were treated and followed up for 18 months. RESULTS Treatment failure was associated with smoking (P = 0.001) and male gender (P= 0.037). Stepwise multiple regression analysis revealed that age, free thyroxine and superior thyroid artery flow rate were predictors of time to remission (P= 0.001, 0.002 and 0.003, respectively). CONCLUSION The time to remission in Graves patients treated with propylthiouracil can be predicted using age, serum free thyroxine and superior thyroid artery flow rate. This may help early consideration of alternative treatment for the patients requiring prolonged treatment for remission or for those who fail medical treatment. This would decrease unnecessary, long-term propylthiouracil exposure with its serious side effects.