Heparin-induced thrombocytopenia: a survey of tests employed and attitudes in haematology laboratories. Groupe d'Etude sur l'Hémostase et la Thrombose (GEHT) de la Société Française d'Hématologie.
A survey was carried out of the attitudes adopted in French laboratories with regard to the diagnosis of heparin-induced thrombocytopenia (HIT). The platelet aggregation assay is used in 100% of laboratories, aggregation being measured by light transmission in an aggregometer (3/4). Blood is drawn either in emergency (1/4) or after heparin discontinuation (1/4). The nature of the samples for testing is a fresh citrated plasma (100%) although frozen plasma is occasionally employed, while 40% of laboratories use less than 3 control platelet donors. Platelet response is verified in the presence of a non immune agonist (18%) or an immune challenge (known positive plasma or platelet activating monoclonal antibody) (13%). Heparin is of the same type as received by the patient and is tested at two or more concentrations of approximately 0.5 and 1.0 IU/ml, but rarely at high concentration (100 IU/ml). The platelet count is adjusted to 250-350 x 10(9)/l (18%), the ratio of patient plasma to PRP is 1:1 (59%), the time of observation is about 20 min (50%) and control platelets are tested with heparin to rule out any false positive results (9/10). Standardization is nevertheless required if the platelet aggregation assay is to be considered as a reference test.
Nguyen
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Laboratoire Central d'Hématologie, CHU Robert Debré, Reims, France.
Lecompte
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D016477:Artifacts; D003625:Data Collection; D004211:Disseminated Intravascular Coagulation; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D007755:Laboratories, Hospital / Q000592:standards*; D010974:Platelet Aggregation; D010976:Platelet Count / Q000379:methods; D010979:Platelet Function Tests / Q000592:standards / Q000706:statistics & numerical data; D010818:Practice Patterns, Physicians'; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013921:Thrombocytopenia / Q000097:blood* / Q000139:chemically induced* / Q000175:diagnosis
D006493:Heparin