Laboratory diagnosis of heparin‐associated thrombocytopenia and comparison of platelet aggregation test, heparin‐induced platelet activation test, and platelet factor 4/heparin enzyme‐linked immunosorbent assay

Abstract

The majority of HAT antibodies react with a PF4/heparin complex, but there is strong evidence that other antigens are involved in some patients. The HIPA test and the PF4/heparin ELISA are sensitive for diagnosing HAT, and they complement one another.

A prospective study of the prevalence of heparin‐induced antibodies and other associated thromboembolic risk factors in pediatric patients undergoing hemodialysis

“…Patients testing negative by ELISA at the first screening were also retested after 3 months. The functional test (HIPA) was performed as previously described [9], using four different washed platelet samples and two heparin concentrations (0.2 and 100 U/mL). Donor platelet responsiveness was carefully controlled by known positive and negative controls [10].…”

“…A positive functional test was defined as a difference of more than 20% in light transmission. The HIPA assay and the ELISA test have sensitivities of 91 and 97%, respectively, and specificities of 77 and 86%, respectively [9].…”

Heparin‐induced thrombocytopenia and thrombosis

“…The PAT is less demanding technically than other ''activation'' assays and is still used by many hospital laboratories. However, it is considerably less sensitive than the SRA and solid phase ELISA tests [37,47,51], and it should not be assumed that a negative test result rules out HIT. A modification of the PAT using washed platelets appear to have greater sensitivity but is technically demanding [52].…”

Risk for heparin-induced thrombocytopenia with unfractionated and low-molecular-weight heparin thromboprophylaxis: a meta-analysis

“…Regardless, the clinical suspicion of heparininduced thrombocytopenia should be confirmed if results of laboratory tests are positive. 5 The frequency of the immune-mediated form, HIT type 2, in prophylaxis studies is unclear, because few studies have addressed HIT type 2 (hereafter referred to as HIT) as either a primary or a secondary outcome. We performed meta-analysis to obtain information on the comparative risks for HIT when UFH and LMWH are used prophylactically in patients at risk for venous thromboembolism.…”