Comparison of selected thrombocytopenic disorders that should be considered when evaluating a patient for heparin-induced thrombocytopenia (HIT).Common clinical manifestations focus on thrombotic versus hemorrhagic symptoms. Comments include relationships to other disorders and/or drugs that need to be considered. HIT has also been reported to occur concomitantly in patients with antiphospholipid syndrome or disseminated intravascular coagulation.
| Disorder . | Common clinical manifestations . | Useful clinical laboratory analyses . | Comments . |
|---|---|---|---|
| LMWH indicates low molecular weight heparin; DIC, disseminated intravascular coagulation; ELISA, enzyme-linked immunosorbent assay; TIA, transient ischemic attack; PT, prothrombin time; PTT, partial thromboplastin time; LDH, lactate dehydrogenase; ADAMTS13, a disintegrin and metalloproteinase with thrombospondin components-13. | |||
| Heparin-induced thrombocytopenia (HIT) | >50% present with thrombosis; venous thrombosis > arterial. | Anti-heparin/PF4 antibody testing (ELISA, functional assays). | Temporal relationship with heparin or LMWH therapy. |
| Antiphospholipid syndrome (APS) | Recurrent venous and/or arterial thromboembolic complications; recurrent fetal loss. | Anticardiolipin antibody and anti-β2-glycoprotein I antibody testing (ELISA); lupus anticoagulant testing. | Autoimmune disorder, either primary or associated with other rheumatologic conditions (eg, lupus); in some cases, may be drug- induced (eg, procainamide). |
| Disseminated intravascular coagulation (DIC) | Hemorrhagic or thromboembolic events predominate, depending on underlying cause and clinical course. | PT, PTT, thrombin time, fibrinogen, D-dimer. | May be acute (eg, associated with sepsis, obstetric complications, severe trauma) or chronic (eg, associated with cancer, aortic aneurysm). DIC can complicate severe HIT. |
| Thrombotic thrombocytopenic purpura (TTP) | Neurologic manifestations may include stroke, TIA, altered mental status, seizures; other symptoms include fever, renal insufficiency. | Microangiopathic hemolytic changes on blood film, elevated LDH, decreased ADAMTS13 levels. | Associated with severe ADAMTS13 deficiency due to inhibitors in most patients; may be seen in patients taking ticlopidine or clopidogrel, or with other drugs, (eg, cyclosporine, tacrolimus, mitomycin). Microangiopathy can also be seen in severe HIT with associated DIC. |
| Drug-induced thrombocytopenia (non-heparin) | Petechiae, purpura, and other hemorrhagic symptoms with severe thrombocytopenia. | Isolated thrombocytopenia, may be severe. | Associated with multiple drugs (eg, abciximab, quinine, multiple antibiotics). |
| Post-transfusion purpura (PTP) | Hematoma, ecchymoses, purpura. | Severe thrombocytopenia that begins approximately five days after blood product use. | Temporal relationship to transfusion therapy; most common in multiparous females. The timing of PTP approximately one week after surgery can mimic HIT. |
| Disorder . | Common clinical manifestations . | Useful clinical laboratory analyses . | Comments . |
|---|---|---|---|
| LMWH indicates low molecular weight heparin; DIC, disseminated intravascular coagulation; ELISA, enzyme-linked immunosorbent assay; TIA, transient ischemic attack; PT, prothrombin time; PTT, partial thromboplastin time; LDH, lactate dehydrogenase; ADAMTS13, a disintegrin and metalloproteinase with thrombospondin components-13. | |||
| Heparin-induced thrombocytopenia (HIT) | >50% present with thrombosis; venous thrombosis > arterial. | Anti-heparin/PF4 antibody testing (ELISA, functional assays). | Temporal relationship with heparin or LMWH therapy. |
| Antiphospholipid syndrome (APS) | Recurrent venous and/or arterial thromboembolic complications; recurrent fetal loss. | Anticardiolipin antibody and anti-β2-glycoprotein I antibody testing (ELISA); lupus anticoagulant testing. | Autoimmune disorder, either primary or associated with other rheumatologic conditions (eg, lupus); in some cases, may be drug- induced (eg, procainamide). |
| Disseminated intravascular coagulation (DIC) | Hemorrhagic or thromboembolic events predominate, depending on underlying cause and clinical course. | PT, PTT, thrombin time, fibrinogen, D-dimer. | May be acute (eg, associated with sepsis, obstetric complications, severe trauma) or chronic (eg, associated with cancer, aortic aneurysm). DIC can complicate severe HIT. |
| Thrombotic thrombocytopenic purpura (TTP) | Neurologic manifestations may include stroke, TIA, altered mental status, seizures; other symptoms include fever, renal insufficiency. | Microangiopathic hemolytic changes on blood film, elevated LDH, decreased ADAMTS13 levels. | Associated with severe ADAMTS13 deficiency due to inhibitors in most patients; may be seen in patients taking ticlopidine or clopidogrel, or with other drugs, (eg, cyclosporine, tacrolimus, mitomycin). Microangiopathy can also be seen in severe HIT with associated DIC. |
| Drug-induced thrombocytopenia (non-heparin) | Petechiae, purpura, and other hemorrhagic symptoms with severe thrombocytopenia. | Isolated thrombocytopenia, may be severe. | Associated with multiple drugs (eg, abciximab, quinine, multiple antibiotics). |
| Post-transfusion purpura (PTP) | Hematoma, ecchymoses, purpura. | Severe thrombocytopenia that begins approximately five days after blood product use. | Temporal relationship to transfusion therapy; most common in multiparous females. The timing of PTP approximately one week after surgery can mimic HIT. |