How I Approach Hematologic Abnormalities in Hospitalized Patients With Infectious Diseases

Patients hospitalized with infectious diseases often develop cytopenias, coagulopathy, hyperinflammation, or tissue abnormalities that may reflect infection, treatment toxicity, organ failure, immune dysregulation, or occult hematologic disease. Drawing on 20 years of daily consultation at the National Institute for Infectious Diseases “Lazzaro Spallanzani” IRCCS, I organize my approach around six recurring scenarios: fever with thrombocytopenia or schistocytes; persistent cytopenia during anti-infective therapy; fever, cytopenias, and hyperferritinemia; pancytopenia prompting marrow assessment; severe anemia or hemolysis; and persistent lymphadenopathy, effusion, or unexplained inflammation, particularly in an immunocompromised patient. Across scenarios, I first identify diagnoses in which delay changes outcome, then integrate tempo, the peripheral blood smear, reticulocyte response, medication, heparin, and transfusion exposure, organ dysfunction, and immune status. Guidelines define diagnostic and therapeutic standards; experience determines how those standards are ordered, combined, and revisited when evidence is incomplete. The approach prioritizes immediate treatment of suspected thrombotic thrombocytopenic purpura, clinically significant disseminated intravascular coagulation, heparin-induced thrombocytopenia or severe drug-induced immune thrombocytopenia, acute promyelocytic leukemia, severe hemolysis, and rapidly progressive secondary hemophagocytic lymphohistiocytosis; disciplined attribution of drug toxicity; physiology-based transfusion and anticoagulation; and timely marrow or tissue diagnosis when infection no longer explains the trajectory. The goal is a reproducible, stewardship-aware bedside method.