The Recurrence Rate of Graves' Disease among Patients with Subclinical Thyrotoxicosis after Initial Remission with Antithyroid Agents

ABSTRACT

BACKGROUND AND OBJECTIVES: The recurrence rate of patients with Graves' disease (GD) is estimated to be 50-55% after withdrawal of antithyroid drug therapy, and relapse is frequent in the first year after discontinuing the medication. Follow-up examination of these patients frequently reveals laboratory findings consistent with subclinical thyrotoxicosis in the first year after stopping the antithyroid agents. We investigated the risk of recurrence of GD among patients with resurfacing subclinical thyrotoxicosis state after remission of initial GD with antithyroid treatments. MATERIALS AND METHODS: We reviewed the patients diagnosed with GD who visited the Department of Endocrinology at two tertiary medical centers: Wonju Severance Christian Hospital and Gangneung Asan Hospital. We enrolled patients whose GD was completely treated after initial treatment with antithyroid agents who then developed subclinical thyrotoxicosis after discontinuation of antithyroid agents. RESULTS: We reviewed a total of 44 patients (29 females, 15 males; age, 48.93±18.04; range, 17-85 years). The recurrence rate was 27.3% (12/44 patients), and recurrence occurred 3 months to 12 months later resurfacing of subclinical thyrotoxicosis. Patients with recurred GD was significantly older than non-recurred patients (44.63±17.75 years vs. 58.58±15.48 years, p=0.02). Other clinical parameters measured at the time of initial diagnosis were not different between the two groups. CONCLUSION: The recurrence rate of GD in patients with resurfacing subclinical thyrotoxicosis after initial remission of the disease was less than 30%. A close monitoring is recommended in these subgroup patients, especially in older patients.