Mechanisms and differential diagnoses of thrombocytopenia
Mechanisms and differential diagnoses of thrombocytopenia
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Clinical scenario and/or diagnostic clues
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Pseudothrombocytopenia
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Platelet aggregates in EDTA-anticoagulated blood; therapy with GPIIbIIIa-receptor antagonists
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Thrombocytopenia is unexpected, and bleeding symptoms are absent; preceding therapy with GPIIbIIIa-receptor antagonists; repeat platelet count in citrated blood and control for aggregates in the blood smear (Note: glycoprotein IIbIIIa antagonists often induce pseudothrombocytopenia in citrated blood)
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Hemodilution
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Infusion of fluids and/or plasma
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Massive infusion/transfusion due to bleeding
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Platelet consumption
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Blood loss
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Bleeding, anemia, and prolonged clotting times as signs of coagulation factor loss and/or consumption
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Massive blunt trauma
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History, physical, and radiological examination
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Disseminated intravascular coagulation
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Shock, infection, obstetrical complications, or other typical underlying causes; prolonged clotting times; increased fibrin split products; nucleated red cells in the differential
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Sepsis
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Fever, further sepsis criteria, and positive blood cultures
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Extracorporeal circuit
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Organ failure requiring extracorporeal circuit; consider areas of high shear stress in the circuit
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Platelet sequestration
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Hepatosplenomegaly
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History, typical comorbidity (e.g. liver cirrhosis or osteomyelofibrosis), and sonography or other diagnostic radiology
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Decreased platelet production
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Intoxication (alcohol and other drugs)
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History of abuse or medication; toxicology screening
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Viral infection (HIV, HCV, EBV, CMV)
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Diagnostic workup of viral infections
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Bone marrow infiltration (leukemia, tumors)
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Bone marrow examination, nucleated red cells in the differential blood film, and teardrop cells
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Radiation
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History
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Chemotherapy
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History
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Platelet destruction
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Immune thrombocytopenia
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Antiplatelet antibodies, normal or increased megakaryocytes in bone marrow, platelet count response to IVIG or steroids, comorbidities typical for secondary ITP (eg, SLE, hepatitis C, CLL)
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DITP
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Medication history (new drug started during the last 7-14 d), platelet counts < 20 × 109/L, increase of platelet counts after cessation of suspected/detected medication, confirmation by detection of drug-dependent antibodies
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Heparin-induced thrombocytopenia
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50% decrease in platelet count (typical nadir 20-80 × 109/L) between days 5 and 14 of heparin treatment, without thromboembolic events with ongoing heparin therapy, heparin-dependent, platelet activating anti-PF4/heparin antibodies
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Thrombotic microangiopathies (TTP, HUS, HELLP syndrome)
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Hemolysis with negative direct Coombs test, fragmented red cells in blood smear, typical platelet count nadir 10-30 × 109/L, thrombotic events with neurological (TTP) or renal (HUS) symptoms, pregnancy (HELLP-syndrome), elevated lactate dehydrogenase
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Posttransfusion purpura
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Transfusion history, history of pregnancy, platelet count nadir < 10 × 109/L, bleeding symptoms, high titer anti–HPA-1a antibodies
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Passive alloimmune thrombocytopenia
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Abrupt, transient fall in the platelet count after transfusion of plasma containing blood products (which passively transmit the platelet alloantibody), typically from a multiparous donor
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