Alterations in thrombopoiesis in patients with thrombocytopenia produced by dengue hemorrhagic fever.

The causes of thrombocytopenia, one of the most dangerous symptoms in the course of dengue hemorrhagic fever (DHF), are not yet clear. We studied patients with DHF (dengue virus type 2), grouped according to days of illness, platelet counts, serum thrombopoietin (Tpo) levels, and bone marrow differential counts. During the thrombocytopenic phase of disease (3rd-8th days) the Tpo levels were not increased in spite of low platelet counts. Beginning from the 6th-7th day in some patients, a rapid increase in Tpo levels was observed, followed by a rise in the platelet counts. By the 9th-11th days all patients studied were in this phase of convalescence. The bone marrow specimens obtained on the 6th-10th days of illness showed a megakaryocytic hyperplasia in 60% of cases. It seems that dengue viruses provoke a transitory alteration in the humoral regulation of thrombopoiesis which possibly may be the consequence of the lymphoid tissue damage. This extends the thrombocytopenic state and contributes to the appearance of hemorrhagic complications.