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Heparin-induced thrombocytopenia.
1Department of Haematology, Prince of Wales Hospital, Randwick, NSW, Australia.
Australian and New Zealand Journal of Medicine
|April 1, 1992
Summary
Heparin therapy can cause two types of thrombocytopenia (HIT). Type II HIT is immune-mediated, increasing thrombosis risk, while Type I is a milder, direct heparin effect.
Area of Science:
- Pharmacology
- Hematology
- Immunology
Background:
- Heparin therapy commonly causes thrombocytopenia, a low platelet count.
- Two distinct types of heparin-induced thrombocytopenia (HIT) exist: Type I (mild, early onset) and Type II (severe, delayed onset).
- Type II HIT is associated with a significant risk of thrombotic complications, potentially leading to severe disability or death.
Purpose of the Study:
- To differentiate between Type I and Type II heparin-induced thrombocytopenia (HIT).
- To elucidate the mechanisms and diagnostic approaches for HIT.
- To provide guidance on managing patients with HIT.
Main Methods:
- Clinical observation and classification of thrombocytopenia during heparin therapy.
- Laboratory confirmation of heparin-dependent antibodies in suspected Type II HIT using platelet aggregometry or 14C-serotonin release assay.
- Review of treatment strategies for HIT.
Main Results:
- Type I HIT is attributed to heparin's direct platelet effects, while Type II HIT involves an immune mechanism with heparin-antibody complexes.
- Diagnosis relies on clinical presentation, with laboratory tests confirming Type II HIT.
- Management involves stopping heparin, initiating warfarin for thrombosis, and considering alternative anticoagulants.
Conclusions:
- Distinguishing between Type I and Type II HIT is crucial due to differing risks and management.
- Prompt diagnosis and appropriate anticoagulation management are vital for patients with HIT.
- Caution is advised with low molecular weight heparins in HIT patients due to potential cross-reactivity.