Underdiagnosis of Heparin-Induced Thrombocytopenia (HIT)

Three factors may help explain the underdiagnosis of HIT:

1.	There is a general lack of awareness[21,30] that may be due, perhaps, to confusion created by the name of the disease, since clinically significant thrombocytopenia (less than 150,000/mcL platelets) may not be present in all patients with HIT.[15,30]
2.	Thrombocytopenia in HIT is paradoxically associated with thrombosis, not with bleeding.
3.	There are a large number of other causes of thrombocytopenia in hospitalized patients (e.g., septicemia/sepsis, hemodilution, disseminated intravascular coagulation, hypercoagulable states, hemodialysis, multisystem organ failure, primary bone marrow disorders, and other concurrent drug therapies).[32]

The diagnosis of HIT should be made first on clinical findings.[17]

Laboratory tests for the diagnosis of HIT are useful; however, they still have limitations. Some laboratory tests are not routinely available for use in the clinical setting.[7,28]

Indications
Argatroban is indicated as an anticoagulant for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia.

Argatroban is indicated as an anticoagulant in patients with or at risk for heparin-induced thrombocytopenia undergoing percutaneous coronary intervention (PCI).

Important Safety Information

As with all anticoagulants, bleeding is a serious concern. Argatroban is contraindicated in patients with overt major bleeding or those with hypersensitivity to the product or any of its components. Argatroban should be used with extreme caution in disease states or other circumstances in which there is an increased risk of hemorrhage. Overall major bleeding was reported in 5.3% of patients with HIT treated with Argatroban versus 6.7% of the historical controls. Overall major bleeding was reported in 1.8% of patients undergoing PCI treated with Argatroban versus 3.1% of the historical controls. Intracranial bleeding was not observed in the 568 patients treated with Argatroban for HIT (with or without thrombosis) or in the 91 patients who underwent PCI. The most common nonhemorrhagic side effects in HIT patients, regardless of the relationship to treatment, were dyspnea, hypotension, and fever. In patients undergoing PCI, the nonhemorrhagic side effects, regardless of the relationship to treatment, included chest pain, hypotension, and back pain. Please see full Prescribing Information for additional safety information on Argatroban.