[Association of Basedow's disease and autoimmune thrombopenic purpura. No effect of hyperthyroidism on antiplatelet autoimmunity].

The association between Graves' disease and autoimmune thrombocytopenic purpura is rare and yet more frequent than would be expected from a mere coincidence. The existence of an immunological disorder common to Graves' disease and autoimmune thrombocytopenic purpura and/or a direct responsibility of hyperthyroidism in the genesis of immunological disturbances resulting in autoimmune thrombocytopenic purpura are hypotheses put forward to try and explain why these two pathologies are associated. We report two cases in which the antiplatelet autoimmunity developed independently of the thyroid functional disorder, making it unlikely that hyperthyroidism played a direct role in the occurrence of the immunological disorders responsible for the autoimmune thrombocytopenic purpura. The physiopathology responsible for the Graves' disease-autoimmune thrombocytopenic purpura association remains imperfectly known. The existence of an immunological pathogenetic mechanism underlying both diseases seems to be likely; it probably acts through an antigenic determinant that is common to thyroid cells and platelets.