[Hematologic changes in leptospirosis]

30 cases of leptospirosis admitted to the Clinica de Doenças Infecciosas e Parasitárias do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo were studied for blood count alterations. 16 patients (53.3%) had a normal white blood cell count at the moment of admission. 12 patients (40%) presented a high white blood cell count and 2 (6.6%) had a low count. 29 patients (96.6%) had a high proportion of neutrophils and 25 patients (83.3%) presented a high number of immature forms. 24 patients had anemia. Thrombocytopenia was present in 26 patients (86.6%). The most characteristic changes found in bone marrow aspirate were the alterations of M:E ratio (myeloid-erythroid ratio) due to relative and/or absolute hyperplasia of the myeloid series, and/or relative and/or absolute hypoplasia of the erythroid series; erythropoiesis was predominantly micro-erythroblastic in many patients; mild to moderate plasmocytosis was found; and, regarding the interstitial series, increased macrophagic activity was noted. There was no direct correlation between the number of megakaryocytes and the blood platelet count, but there was a direct correlation between the bone marrow platelet production and blood platelet count. We believe that it is very difficult to have a good idea of the dynamic mechanisms that lead to medullar platelet production in the presence of platelet consumption, through a random test of the bone marrow.