Thrombopénie ferriprive : un diagnostic différentiel rare du purpura thrombopénique auto-immun

Abstract

Iron deficiency is typically associated with microcytic anemia and thrombocytosis. It is a very uncommon cause of thrombocytopenia. A 17-year-old female presented with marked fatigue and dyspnea on exertion. Review of systems was only remarkable for abundant menstruations during the past two years. The hemogram revealed a profound microcytic anemia (4.4 g/dL, mean corpuscular volume [MCV] 49 fL) and a thrombocytopenia (33 G/L). Marked iron deficiency was also present: ferritinemia <3 μg/L. Investigations did not find any cause of iron deficiency anemia other than excessive menstrual loss. Bone marrow examination showed an increase number of megakaryocytes, compatible with an immune thrombocytopenia purpura. Iron supplementation completely normalized the platelet count within 48 hours. Iron affects thrombopoiesis. Because the number of megakaryocytes may then increase in the bone marrow, "iron deficiency thrombocytopenia" may be falsely diagnosed as immune thrombocytopenic purpura, leading to inappropriate corticosteroid therapy. Iron supplementation is the appropriate treatment of iron deficiency thrombocytopenia and allowed a rapid correction of the platelet count in all the 24 cases that have been previously reported with sufficient detail to be analyzed in the literature.