"Block-and-replace" treatment in Graves' disease: experience in a cohort of pediatric patients

The "block-and-replace" (BR) method involves the use of a high dose of antithyroid drugs (ATD) with levothyroxine (L-T4). Its use in the management of Graves' disease (GD) is still debated mainly because the frequency of side effects of ATD is dose dependent. We retrospectively studied the effect of medium dose of ATD with L-T4 versus monotherapy with ATD in pediatric patients with unstable GD.

28 pediatric patients with GD with unstable response to ATD were treated with L-T4 and medium dose of ATD. We compared the rate of euthyroidism, hypothyroidism and hyperthyroidism episodes observed during treatment with methimazole alone with those observed during the BR approach. We evaluated the occurrence of side effects and the rate of remission in patients treated with ATD + L-T4 therapy and the efficacy of combination therapy to postpone a definitive treatment (radioiodine and thyroidectomy).

Patients showed a better control of thyroid function during the BR therapy, presenting fewer episodes of hyperthyroidism and hypothyroidism. No serious side effects during the BR approach were observed. Only one patient went into remission with the ATD + L-T4 therapy. Fifteen patients required a definitive therapy (4 radioiodine, 11 thyroidectomy). The use of BR method has delayed radioiodine treatment for 4.9 years and surgery for 2.9 years.

The BR method does not increase the remission rates. It may be useful to combine L-T4 with a medium dose of methimazole when GD is difficult to manage with methimazole alone. It may represent a therapeutic option to postpone definitive treatments to a suitable age.