Mechanisms and differential diagnoses of thrombocytopenia
Mechanisms and differential diagnoses of thrombocytopenia
|
Clinical scenario and/or diagnostic clues
|
Pseudothrombocytopenia
| |
Platelet aggregates in EDTA-anticoagulated blood; therapy with GPIIbIIIa-receptor antagonists
|
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)
|
Hemodilution
| |
Infusion of fluids and/or plasma
|
Massive infusion/transfusion due to bleeding
|
Platelet consumption
| |
Blood loss
|
Bleeding, anemia, and prolonged clotting times as signs of coagulation factor loss and/or consumption
|
Massive blunt trauma
|
History, physical, and radiological examination
|
Disseminated intravascular coagulation
|
Shock, infection, obstetrical complications, or other typical underlying causes; prolonged clotting times; increased fibrin split products; nucleated red cells in the differential
|
Sepsis
|
Fever, further sepsis criteria, and positive blood cultures
|
Extracorporeal circuit
|
Organ failure requiring extracorporeal circuit; consider areas of high shear stress in the circuit
|
Platelet sequestration
| |
Hepatosplenomegaly
|
History, typical comorbidity (e.g. liver cirrhosis or osteomyelofibrosis), and sonography or other diagnostic radiology
|
Decreased platelet production
| |
Intoxication (alcohol and other drugs)
|
History of abuse or medication; toxicology screening
|
Viral infection (HIV, HCV, EBV, CMV)
|
Diagnostic workup of viral infections
|
Bone marrow infiltration (leukemia, tumors)
|
Bone marrow examination, nucleated red cells in the differential blood film, and teardrop cells
|
Radiation
|
History
|
Chemotherapy
|
History
|
Platelet destruction
| |
Immune thrombocytopenia
|
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)
|
DITP
|
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
|
Heparin-induced thrombocytopenia
|
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
|
Thrombotic microangiopathies (TTP, HUS, HELLP syndrome)
|
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
|
Posttransfusion purpura
|
Transfusion history, history of pregnancy, platelet count nadir < 10 × 109/L, bleeding symptoms, high titer anti–HPA-1a antibodies
|
Passive alloimmune thrombocytopenia
|
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
|