Immature platelet fraction can help adjust therapy in refractory thrombotic microangiopathic hemolytic anemia cases.

Hemolytic uremic syndrome and thrombotic thrombocytopenic purpura share presentations, therapies and diagnostic evaluation of activity of the metalloprotease ADAMTS13. Here, we report a patient with the clinical presentation of thrombotic microangiopathic thrombocytopenia, normal ADAMTS13, prolonged regimen of therapeutic plasma exchanges (TPEs), bone marrow biopsy showing adequate tri-lineage hematopoiesis, and low immature platelet fraction (%-IPF) (<1.0%). Low %-IPF suggested platelet hypoproduction; high steroid therapy, in conjunction with TPEs, resulted in the recovery of platelet count. Further investigation is needed to determine if %-IPF can guide therapy in cases of microangiopathic hemolytic anemias refractory to therapy.