Heparin-induced thrombocytopenia: laboratory diagnosis and management

Heparin-induced thrombocytopenia (HIT), a drug-induced immunohaematological adverse reaction, is a rare but potentially very severe condition. The mai n problem for this complex syndrome is its recognition and management, whic h should be as early as possible to avoid the development of life-threateni ng complications. Most studies have reported heterogeneous populations of p atients with other diseases that potentially induce thrombocytopenia. There is no gold standard diagnostic criteria, and we have established a score w ith anamnestic criteria that allows us to evaluate the likelihood of Hn: In clinical practice, the diagnosis is based on the analysis of clinical feat ures and laboratory tests. Platelet aggregation test (PAT) and an ELISA tes t (heparin platelet-induced antibodies) are generally performed by expert l aboratories to confirm the occurrence of HIT. In our experience, both tests are concordant in the majority of patients. PAT seems to correlate better with the clinical features while ELISA appears more specific. Regarding the ir limits, both are complementary in the determination of HIT diagnosis cou pled to the clinical score system. The treatment often requires a multidisc iplinary approach. Danaparoid (Orgaran(R)) or lepirudin (Refludan(R)) are t he two alternative treatments for HIT patients with marketing approval. To avoid further exposure to heparin, every HIT patient should carry a written document that confirms the immunoallergy.