Rosborough Terry K, Jacobsen Jennifer M, Shepherd Michele F
Medical Education Department and Coagulation Laboratory, Abbott Northwestern Hospital, Minneapolis, Minnesota 55407, USA.
Blood Coagul Fibrinolysis. 2010 Apr;21(3):242-4. doi: 10.1097/MBC.0b013e32833581a3.
Warfarin therapy is used in lupus anticoagulant patients with thrombosis and yet the prothrombin time (PT)/international normalized ratio (INR) in these patients can sometimes be falsely elevated. Both a PT-based factor II (FII) assay and a chromogenic, enzymatic factor X (CFX) assay have been used for monitoring when the INR may be artifactual. This study compared FII and CFX assays in lupus anticoagulant-positive and lupus anticoagulant-negative warfarin-treated patients in a cross-sectional study of samples from 21 lupus anticoagulant-positive and 19 lupus anticoagulant-negative outpatients. Plasma samples were simultaneously measured for FII and CFX and the ratio of FII/CFX was used to measure concordance. Compared with lupus anticoagulant-negative patients 14 of the 21 lupus anticoagulant-positive patients had lower FII/CFX ratios (P < 0.01). Three of the patients had ratios less than 0.6 indicating strong disagreement (P < 0.0001). The patient with the lowest FII/CFX ratio had evidence suggesting a specific antibody to FII. Another patient showed that the discordance between FII and CFX varied over time. The CFX assay in the laboratory was technically superior, more precise, and less costly. The CFX assay is preferred for warfarin therapy monitoring in lupus anticoagulant patients when INR artifacts are suspected.
华法林疗法用于患有血栓形成的狼疮抗凝物患者，但这些患者的凝血酶原时间（PT）/国际标准化比值（INR）有时可能会被错误地升高。当INR可能出现人为因素影响时，基于PT的凝血因子II（FII）检测和发色底物法、酶促凝血因子X（CFX）检测均已用于监测。本研究在一项横断面研究中，对21例狼疮抗凝物阳性和19例狼疮抗凝物阴性门诊患者的样本进行比较，这些患者均接受华法林治疗。同时检测血浆样本中的FII和CFX，并使用FII/CFX比值来衡量一致性。与狼疮抗凝物阴性患者相比，21例狼疮抗凝物阳性患者中有14例的FII/CFX比值较低（P<0.01）。其中3例患者的比值小于0.6，表明存在强烈分歧（P<0.0001）。FII/CFX比值最低的患者有证据表明存在针对FII的特异性抗体。另一名患者显示FII和CFX之间的不一致性随时间变化。实验室中的CFX检测在技术上更优越、更精确且成本更低。当怀疑存在INR人为因素影响时，CFX检测更适合用于狼疮抗凝物患者的华法林治疗监测。
