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ABSTRACT
The aim of this retrospective study is to assess the annual incidence of different types of hyperthyroidism (HT) and to report our experience with antithyroid therapy in Graves' disease after iodized salt prophylaxis in Turkey from 1990 to 2000. For this purpose the outpatient files of 12574 thyroid patients were revised. Clinical examination , serum TSH, thyroid hormone levels, serum thyroid autoantibody titers, thyroid ultrasonography and scintigraphy were defined before diagnosis. HT was classified as immunogenic HT [Graves disease, (GD)] and HT with intrinsic thyroid autonomy [Toxic Multinodular Goitre (TMG) and Toxic Adenoma (TA)]. Hyperthyroidism was determined in 766 (6.09%) out of 12574 thyroid patients. The diagnoses were as follows: GD 54.5%, TMG 39.6%, TA 4.6% and Subacute Thyroiditis (ST) 1.04%. The time course of different types of HT was different: after the use of iodine in the 1990s the annual distribution of HT per year was decreased in TMG (p=0.001, r=-0.846) and increased in GD (p=0.001, r=0.916). The mean observation period was 42.3±10.6 months in the patients with GD. Increased TSH Receptor Antibody (TSHRAb) titers were measured in only 55.6 % of all the patients with GD. The annual distribution of increased TSHRAb ranges per year did not change, but the mean TSHRAb level was increased. The mean TSHRAb titer was doubled in 2000 compared to 1990. Treatment with antithyroid drugs (ATD) was the first choice in GD (94.7%). The mean course of ATD therapy was 18±5.7 months and the induction interval of remission was 2±1.4 months. In 3 years follow-up 87.2% of patients were still in remission, whereas 13.8% had relapsed once and 0.47% had relapsed twice. The probability of relapse correlates weakly with TSHRAb level (p=0.04, r=0.295), length of remission (p=0.031, r=0.264) and is negatively correlated with time to induction remission (p=0.002, r=-0.379). The course of ATD therapy was correlated neither with relapse frequency (p=0.606, r=-0.082) nor with duration of remission (p=0.796, r=0.026). Our data indicated that the frequency of GD and the detectable TSHRAb levels were increased with iodine prophylaxis. We suggest that antithyroid drugs have a significant role in the first stage treatment of GD, especially in a population with low THSRAb levels. The treatment with ATD could be more successful if the dose is reduced at the exact true point of time that is determined according to the clinical and laboratory remission criteria.
The aim of this retrospective study is to assess the annual incidence of different types of hyperthyroidism (HT) and to report our experience with antithyroid therapy in Graves' disease after iodized salt prophylaxis in Turkey from 1990 to 2000. For this purpose the outpatient files of 12574 thyroid patients were revised. Clinical examination , serum TSH, thyroid hormone levels, serum thyroid autoantibody titers, thyroid ultrasonography and scintigraphy were defined before diagnosis. HT was classified as immunogenic HT [Graves disease, (GD)] and HT with intrinsic thyroid autonomy [Toxic Multinodular Goitre (TMG) and Toxic Adenoma (TA)]. Hyperthyroidism was determined in 766 (6.09%) out of 12574 thyroid patients. The diagnoses were as follows: GD 54.5%, TMG 39.6%, TA 4.6% and Subacute Thyroiditis (ST) 1.04%. The time course of different types of HT was different: after the use of iodine in the 1990s the annual distribution of HT per year was decreased in TMG (p=0.001, r=-0.846) and increased in GD (p=0.001, r=0.916). The mean observation period was 42.3±10.6 months in the patients with GD. Increased TSH Receptor Antibody (TSHRAb) titers were measured in only 55.6 % of all the patients with GD. The annual distribution of increased TSHRAb ranges per year did not change, but the mean TSHRAb level was increased. The mean TSHRAb titer was doubled in 2000 compared to 1990. Treatment with antithyroid drugs (ATD) was the first choice in GD (94.7%). The mean course of ATD therapy was 18±5.7 months and the induction interval of remission was 2±1.4 months. In 3 years follow-up 87.2% of patients were still in remission, whereas 13.8% had relapsed once and 0.47% had relapsed twice. The probability of relapse correlates weakly with TSHRAb level (p=0.04, r=0.295), length of remission (p=0.031, r=0.264) and is negatively correlated with time to induction remission (p=0.002, r=-0.379). The course of ATD therapy was correlated neither with relapse frequency (p=0.606, r=-0.082) nor with duration of remission (p=0.796, r=0.026). Our data indicated that the frequency of GD and the detectable TSHRAb levels were increased with iodine prophylaxis. We suggest that antithyroid drugs have a significant role in the first stage treatment of GD, especially in a population with low THSRAb levels. The treatment with ATD could be more successful if the dose is reduced at the exact true point of time that is determined according to the clinical and laboratory remission criteria.