Ptp

DIC secondary to procoagulant material(s)

produced by neoplastic cells Platelet activation by clot-bound thrombin Hyperaggregable platelets in ketoacidosis (?) Multiple mechanisms described, including platelet activation by antiphospholipid antibodies (?) Platelet activation by thrombin bound to fibrin degradation products (?) Symmetrical peripheral gangrene secondary to DIC with depletion of protein C and antithrombin Infection-associated thrombocytopenia; ischemic events secondary to septic emboli Platelets susceptible to complement-mediated damage; platelet hypoproduction Anti-ADAMTS13 autoantibodies modulated by the postoperative state (?)

Usually secondary to natural anti-GPIIb/IIIa antibodies; bleeding more common than thrombosis "Pseudospecific" alloantibody-mediated platelet destruction (exception: bleeding, not thrombosis)

Latea

Earlyb or latec

Earlyd

Early

Earlye Early

Early Early

Early or late

Early

Late

Note: These pseudo-HIT disorders can mimic HIT by causing thrombocytopenia and thrombosis in association with heparin treatment. An exception is PTP, which causes bleeding, but not thrombosis; however, PTP can resemble HIT because both disorders usually occur about a week after major surgery requiring blood and postoperative heparin. The pseudo-HIT disorders can be categorized based on whether the onset of thrombocytopenia is typically "early" (<5 days) or "late" (>5 days) in relation to the heparin. aSee Fig. 1 for an example of pseudo-HIT caused by adenocarcinoma-associated DIC. bSee Fig. 3 for early thrombocytopenia associated with pulmonary embolism. cSee Fig. 4 for late thrombocytopenia associated with pulmonary embolism. dSee Fig. 5 for early thrombocytopenia associated with diabetic ketoacidosis. eSee Fig. 6 for early thrombocytopenia caused by thrombolytic therapy.

Abbrevations: ADAMTS, a disintegrin and metalloprotease with thrombospondin-1-like domains; DIC, disseminated intravascular coagulation; GP, glycoprotein; HIT, heparin-induced thrombocytopenia; PTP, posttransfusion purpura; TTP, thrombotic thrombocytopenic purpura.

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