Suppression of serum thyrotropin with thyroxine in patients with Graves' disease: Effects on recurrence of hyperthyroidism and thyroid volume

Based on findings that thyroxine may have a beneficial effect on the recurrence of Graves' hyperthyroidism, we prospectively studied the effects of a TSH suppressive treatment with thyroxine on the course of Graves' disease in fifty patients with recent onset of hyperthyroidism. After the normalization of serum tri-iodothyronine (T-3) and thyroxine (T-4) concentrations, one group of patients was randomly assigned to a combined treatment with carbimazole and a TSH suppressive dose of T-4 for 12 months, followed by another 12 months of TSH suppressive therapy alone. The other group of patients also received carbimazole for one year, but T-4 was only added as indicated to normalize elevated TSH serum concentrations, and patients received no therapy during the second year. By the end of the second year, a relapse of hyperthyroidism had occurred in 43% of the patients with and in 45% of the patients without suppressive T-4 treatment. Ln those patients without a relapse of hyperthyroidism, initial thyroid size significantly (P = 0.01) decreased with time in both treatment groups, However, patients on suppressive T-4 treatment tended to have a greater reduction in thyroid volume than patients with normal TSH serum concentrations (P = 0.05). In conclusion, we were unable to detect a preventive effect of exogenous TSH suppression on the recurrence of hyperthyroidism. However, our data suggest that TSH suppressive treatment may have a beneficial effect on thyroid enlargement in Graves' disease.