Abstract
Immune thrombocytopenia (ITP) is an entity characterized by a platelet count of less than 100 × 10(9)/L in the absence of other causes of thrombocytopenia, such as viral infections, rheumatic diseases, or drugs. Grave's disease is also an autoimmune condition in which thrombocytopenia is often observed. Moreover, in the literature, many reports show a marked interference of the thyroid dysfunction (mainly hyperthyroidism) in the control of thrombocytopenia. Although this issue still remains debatable, the authors report the case of a young woman with a previous diagnosis of ITP with a brilliant initial response to corticotherapy. Some years after this diagnosis, the patient presented thyrotoxicosis due to Grave's disease and the thrombocytopenia relapsed, but this time there was no response to the glucocorticoids. Only after the radioiodine I-131 thyroid ablation the control of thrombocytopenia was achieved. The authors call attention to this overlap and for testing thyroid function in every patient with an unexpected negative response to corticotherapy.