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Weetman, Sheffield, UK, discussed the controversy if antithyroid
drugs (ATD) and T4 treatment have immunosuppressive effects in Graves'
disease. Both methimazole and perchlorate have shown to suppress autoimmune
thyroiditis in experimental animals. The same is true for T4 treatment.
These effects have been shown in rats and also in the obese chicken. Not
only methimazole but also perchlorate have shown to the opinion of Weetman,
to favourably influence the course of Graves' disease in humans, although
the effect of methimazole was greater than that of perchlorate. ATD, to
his opinion, exert the effect locally in the thyroid by inhibition of production
of free radicals, prostaglandin 2, and interleukin 6 and 1. ATD probably
also reduce the production of immunoglobulins, and the expression of MHC
I and production of heatshock proteins. (Comment: If ATD and T4 have indeed
immunosuppressive effects, then there is a rationale to treat patients
with high dose antithyroid drugs in combination with thyroid hormone instead
of low dose ATD only.)
Gorman, Rochester, MN, USA, discussed treatment of ophthalmic Graves' disease (OGD), using radioactive iodine (RAI). The controversy regards potential harmful effects of RAI treatment on the development of OGD. The speaker reviewed the literature and came to the conclusion that RAI has no harmful effect on OGD but that this possibility was created in the literature because of the fact that OGD usually develops after the onset of hyperthyroidism. Thus, when patients are treated with RAI for hyperthyroidism, OGD starts to develop and this created the idea that RAI induced these eye symptoms whereas in fact the later development of OGD belonged to the natural course of the disease. Cooper, Baltimore, MD, USA, discussed the different opinions regarding the possibility to predict remissions or relapses after ATD treatment in Graves' disease. On the basis of the literature he came to the conclusion that there are no reliable parameters available to this end. He also discussed recent publications indicating that combination of ATD with T4 leads to a lower relapse rate than low dose ATD only. In this respect the communication of Jaffiol, Montpellier, France, should be mentioned. He reported treatment results in patients with Graves' disease. Twenty-four patients (Gr I) were treated with carbimazole + TRIAC, 15 patients (GrII) with carbimazole + T3, and 12 patients (GrIII) with only carbimazole for Graves' disease. Therapy was discontinued when early thyroidal radioiodine uptake was normalized. Six months post-therapy remission rate in GrI was 88%, in GrII 80%, and in Gr III 66%. Goiter size increased during therapy in Gr III, but decreased in Gr II and I. It was concluded that combination therapy, resulting in suppression of TSH, increased remission rate and decreased goiter size. A reduction of goiter size and normalisation of early radioiodine uptake at 6 months during therapy appeared to be valuable signs of good prognosis. The speaker finally concluded that ATD treatment should only be used in patients with Graves' disease, having no or small goiters, and that addition of T4 to ATD results in higher remission rates as compared to ATD treatment only. |
