Kamal Fatmawati, Othman Halimatun Radziah
Department of Pathology, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Selangor, Malaysia.
Department of Clinical Diagnostic Laboratories, Hospital Al-Sultan Abdullah, Puncak Alam, Selangor, Malaysia.
Am J Case Rep. 2025 Jan 29;26:e945579. doi: 10.12659/AJCR.945579.
BACKGROUND Lupus anticoagulants (LA) can interfere with routine coagulation tests such as the activated partial thromboplastin time (aPTT) and prothrombin time (PT). The international normalized ratio (INR) is derived from PT and is used to monitor warfarin therapy. A positive LA result is one of the laboratory criteria of the 2023 ACR/EULAR antiphospholipid syndrome (APS) classification criteria. We report a case in which LA interfered with INR measurement in an APS patient. CASE REPORT Our patient was a 45-year-old man who had experienced multiple episodes of thromboembolism. His INR was consistently high, despite not being on any anticoagulant. Our laboratory used a recombinant PT reagent, Siemens Healthineers Dade® Innovin® on a fully automated coagulometer, the Sysmex CS-2500. PT measurements were repeated using 2 different analyzers, the Sysmex CA-104 and Werfen ACL Top 550 CTS. The PT results were 40.5 s (reference range (RR): 9.3-10.8 s) and 56 s, using Sysmex CS2500 and CS104, respectively. However, the PT was 13.4 s (RI: 10.3-12.7 s) using Werfen ACL Top 550 CTS. We retested the sample using Thromborel® S, a tissue-derived PT reagent, and PT was found to be within the reference range. The patient tested positive for LA, anti-cardiolipin, and anti-beta2 glycoprotein I antibodies. CONCLUSIONS LA can falsely prolong the PT when a recombinant PT reagent is used. When we retested the plasma using a tissue-derived PT reagent - Thromborel® S - PT was within normal limits. Thus, it is important to acknowledge that LA can react differently with different PT reagents.
狼疮抗凝物（LA）可干扰常规凝血试验，如活化部分凝血活酶时间（aPTT）和凝血酶原时间（PT）。国际标准化比值（INR）由PT得出，用于监测华法林治疗。LA结果呈阳性是2023年美国风湿病学会（ACR）/欧洲抗风湿病联盟（EULAR）抗磷脂综合征（APS）分类标准的实验室标准之一。我们报告1例LA干扰APS患者INR测量的病例。病例报告：我们的患者是一名45岁男性，曾经历多次血栓栓塞事件。尽管未使用任何抗凝剂，但其INR一直很高。我们实验室在全自动凝血仪Sysmex CS-2500上使用重组PT试剂西门子医疗Dade® Innovin®。使用2种不同分析仪Sysmex CA-104和Werfen ACL Top 550 CTS重复进行PT测量。使用Sysmex CS2500和CS104时，PT结果分别为40.5秒（参考范围（RR）：9.3 - 10.8秒）和56秒。然而，使用Werfen ACL Top 550 CTS时，PT为13.4秒（参考区间：10.3 - 12.7秒）。我们使用组织来源的PT试剂Thromborel® S对样本进行重新检测，发现PT在参考范围内。该患者LA、抗心磷脂和抗β2糖蛋白I抗体检测均呈阳性。结论：使用重组PT试剂时，LA可错误延长PT。当我们使用组织来源的PT试剂Thromborel® S对血浆进行重新检测时，PT在正常范围内。因此，必须认识到LA与不同PT试剂反应不同。
