Potential interferences for each assay type are discussed, including lupus anticoagulants, heparin, warfarin, direct thrombin inhibitors (such as argatroban, dabigatran, hirudin, or bivalirudin), rivaroxaban, factor deficiencies or elevations, factor V Leiden, and specific mutations that the assay(s) might not be able to detect.
In this study, we evaluated 40 patients with antiphospholipid syndrome and thrombosis, 31 primary and nine secondary to systemic lupus erythemathosus, to estimate the carrier rates of factor V Leiden, 20210A --> G prothrombin variant and 677C --> T in the MTHFR gene.
This reduction in APC-R ratio was not explained by (1) the presence of the factor V Leiden, found in only one of 165 patients with SS disease including those tested for APC-R, or (2) the presence of lupus anticoagulants.