Outcome of Very Long-Term Treatment with Antithyroid Drugs in Graves' Hyperthyroidism Associated with Graves' Orbitopathy

Abstract

It is still debated which treatment modality for Graves' hyperthyroidism (GH) is most appropriate when Graves' orbitopathy (GO) is present. The preference in our center has been always to continue antithyroid drugs for GH (as the block-and-replace [B-R] regimen) until all medical and/or surgical treatments for GO are concluded and the eye disease does not require any further therapy (except prescription of lubricants). This usually takes more than 2 years. The aim of this study was to evaluate the outcome of long-term B-R regimen for GH in GO patients by assessment (after discontinuation of B-R) of (a) the recurrence rate of GH and (b) the relapse rate of GO and its association with recurrent GH and/or (131)I therapy. A retrospective follow-up study was done among all patients referred to the Academic Medical Center in Amsterdam between 1995 and 2005 for GO. The inclusion criteria for the study were a history of GH and GO and a history of treatment for GH with a B-R regimen for more than 2 years. The exclusion criteria were a history of (131)I therapy or thyroidectomy before the end of GO treatment. A questionnaire was sent to 255 patients and returned by 114. Of these patients, 73 qualified for the study. Recurrences of GH and/or GO as indicated by returned questionnaires were checked with treating physicians. Patients were treated with B-R for a median of 41 months (range: 24-132). The median follow-up after discontinuation of the B-R regimen was 57 months (range: 12-170). Recurrent GH occurred in 27 of the 73 study patients (37%) at a median of 3 months (range: 1-65) after withdrawal of antithyroid drug therapy. Nineteen of the 27 patients with recurrent hyperthyroidism were treated with (131)I therapy. A relapse of GO was not encountered in any of the 73 patients. The study suggests that long-term B-R treatment of GH in GO patients is associated with a recurrence rate of hyperthyroidism of about 37%. With the regimen employed, recurrence of hyperthyroidism and recurrence of hyperthyroidism followed by treatment with (131)I appears not to be a likely cause of relapse of GO. The data suggest that B-R treatment of GH until GO has become inactive and does not require any further treatment is a feasible option and does not jeopardize the improvement that occurred in GO.