Sustained Control of Hyperthyroidism in Graves’ Disease: Comparison of Thyroidectomy and Long-Term Antithyroid Treatment

Abstract

Background: The achievement of sustained euthyroidism in patients with Graves’ hyperthyroidism may reduce the risk of mortality and cardiovascular events. Objectives: We compared the time to euthyroidism and the time remaining in euthyroidism following total thyroidectomy and long-term methimazole (LT-MMI) treatment. Methods: In this prospective cohort study, two hundred and eight patients with diffuse toxic goiter, 104 (84 women) with total thyroidectomy, and 104 (84 women) on LT-MMI were compared. All patients received adequate levothyroxine treatment after thyroidectomy. Data on serum free thyroxine (fT4), triiodothyronine (T3), and thyrotropin (TSH) every 6 months until the end of follow-up were analyzed. The time to normalization of serum thyroid hormones and TSH concentrations and the percentage of time that thyroid hormones and TSH levels remained within the normal range during a mean follow-up of 11 years were compared between the two study groups using t-test, Mann-Whitney U, chi-square, and Fisher exact tests. Results: The mean time to euthyroidism was 4.74 ± 2.42 and 4.48 ± 2.54 months in the thyroidectomy and LT-MMI groups, respectively. During follow-up, the percentage of time spent in euthyroidism was 82.67 ± 7.33% vs 94.21 ± 6.98% in the thyroidectomy and LT-MMI groups, respectively (P < 0.001). Patients with thyroidectomy spent more time in subclinical and clinical hypo- and hyperthyroidism compared to LT-MMI patients. Permanent hypocalcemia and vocal cord paralysis occurred in 2 and 1 patients, respectively. Conclusions: Treatment of hypothyroidism after total thyroidectomy was accompanied by less sustained euthyroidism during long-term follow-up compared with LT-MMI therapy. This difference may be important for the risk of mortality and cardiovascular events, demanding long-term studies for comparison of these outcomes in patients treated with total thyroidectomy and LT-MMI treatment.