3 research outputs found
The effect of unfractionated heparin, enoxaparin, and danaparoid on lupus anticoagulant testing: Can activated carbon eliminate falseâpositive results?
Abstract Background Heparins and heparinoids interfere with functional clotting assays used for lupus anticoagulant (LAC) detection. However, current guidelines for LAC testing do not provide clear guidance on this matter. Objectives We aimed to assess to effect of unfractionated heparin (UFH), enoxaparin, and danaparoid on LAC assays over broad antiâXa activity ranges and to evaluate whether activated carbon (AC) is able to neutralize these effects. Methods UFH (0.1â3.0Â IU/mL), enoxaparin (0.2â2.9Â IU/mL), and danaparoid (0.6â2.2Â IU/mL) were spiked to normal pooled plasma. AC was added at multiple activity levels. AntiâXa assays and LAC tests were performed on all samples using Stago analyzers and reagents. Results Abnormal activated partial thromboplastin time (APTT) screening and mixing tests were obtained at the lowest levels for all compounds. Abnormal APTT confirmation tests were seen from 2.5 and 1.9 antiâXa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dilute Russellâs viper venom test (dRVVT) screening tests were obtained from 1.6, 1.4, and 1.1 antiâXa IU/mL for UFH, enoxaparin, and danaparoid, respectively. Mixing tests were abnormal from 2.5 and 1.3 antiâXa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dRVVT confirmation results were seen for danaparoid only from 1.9 antiâXa IU/mL. AC was unable to neutralize antiâXa activity in plasma and overcome the effect of the tested anticoagulants on LAC assays but may cause prolongation of APTT clotting times. Conclusions UFH, enoxaparin, and danaparoid clearly affected LA tests; however, falseâpositive LAC conclusions were obtained at supratherapeutic enoxaparin and danaparoid levels only. AC may prolong APTT screen clotting times, requiring 3âstep testing to avoid potential misdiagnosis of LAC