Adult lupus anticoagulant hypoprothrombinemia syndrome with combined factor II and X deficiencies: diagnostic and therapeutic challenges

Background: Lupus anticoagulant hypoprothrombinemia syndrome (LAHPS) is a rare, acquired coagulopathy characterized by the presence of lupus anticoagulant and deficiency of factor II, causing paradoxical bleeding despite prothrombotic antibodies. LAHPS may cause falsely low INR values, complicating the dosing and monitoring of anticoagulation by vitamin K antagonists. Key Clinical Question: How can anticoagulation be safely administered in patients with autoimmune disease who require vitamin K antagonist therapy when LAHPS interferes with accurate INR monitoring? Clinical Approach: We report the case of a 53-year-old woman with a family history of rheumatic diseases who developed unusual INR fluctuations during vitamin K antagonist administration following mechanical valve replacement. Workup revealed reduced factor II and factor X levels with positive lupus anticoagulant, consistent with LAHPS. Anticoagulation was subsequently guided by factor activity level monitoring and clinical assessment rather than INR alone with no thromboembolic or major bleeding events being reported. Conclusion: This case highlights a rare presentation of adult LAHPS with dual factor deficiency and illustrates how lupus anticoagulant may distort INR monitoring, complicating anticoagulation management.