DRUG-THERAPY OF THYROID AUTOIMMUNE DISORDERS

The autoimmune thyroid diseases include a remarkable set of varied dis orders. They include atrophic or goitrous thyroiditis with hypothyroid ism, euthyroid goitre, postpartum thyroiditis and hyperthyroid Graves' disease with or without extrathyroidal manifestations. Up to the pres ent, treatment of these conditions has been merely symptomatic and aim s at the restoration of euthyroidism. Treatment of Graves' disease, ei ther medical (antithyroid drugs) and conservative, or ablative (radioa ctive iodine or subtotal thyroidectomy), is far from satisfactory, as is the treatment of Graves' ophthalmopathy. The risk-benefit ratio of each therapeutic modality must be carefully weighted and adapted to ev ery patient. Antithyroid drugs such as thiamazole, carbimazole or prop ylthiouracil have advantages of fair tolerability, immediate efficacy and lack of irreversible hypothyroidism. However, their use is marked by a 50% relapse rate even after an Is-month course, and it is not yet clear whether the daily dosage of the drug affects the relapse rate. There is no basis for a clear identification of these patients who wil l remain in remission after antithyroid drug treatment, either initial ly or during treatment. However, young age, large goitres and persiste nce of elevated titres of anti-thyrotropin receptor antibodies after s everal months of treatment are likely to be associated with relapse. I n the various forms of thyroiditis, thyroxine replacement therapy repr esents the only therapeutic approach. Initiation of therapy with thyro xine may present difficulties such as manifestation of pre-existing he art disease. Because of their high prevalence, heterogeneous presentat ion and easy clinical and biological identification, autoimmune thyroi d diseases should represent fruitful models of human organ-specific au toimmune disease. Although intense research is currently devoted to th e aetiology, pathogenesis and pathophysiology of the autoimmune thyroi d diseases, no new specific immunologically based intervention has yet been proposed. The question remains open of a possible immunomodulato ry action of antithyroid drugs or thyroxine in autoimmune thyroid dise ases. However, there is no doubt that, in the future, immunotherapeuti c strategies devised in animal models and tested in selected human dis eases will be applied to the more severe forms of autoimmune thyroid d iseases, or used prophylactically when disease occurrence can be predi cted.