Recurrent venous thromboembolism in primary membranous nephropathy despite direct Xa inhibitor therapy

Clinically apparent venous thromboembolism (VTE) occurs in approximately 7% of patients with membranous nephropathy. Hypoalbuminemia at diagnosis is an independent risk factor for VTE, and risk increases significantly as albumin falls. Optimal prophylactic and treatment anticoagulation regimens in the nephrotic syndrome remain unproven but novel oral anti-coagulants have become attractive therapeutic options. We describe a patient diagnosed with anti-phospholipase A2 receptor antibody positive membranous nephropathy and recurrent VTE while on therapeutic dosing of apixaban. A direct factor Xa inhibitor, apixaban has been shown to be non-inferior to warfarin for the treatment of VTE in the general population. However, because it is highly protein-bound, apixaban may have altered pharmacokinetics and pharmacodynamics in patients with nephrotic syndrome and hypoalbuminemia. This case report highlights the need for further studies of direct oral anticoagulants to fully assess their effectiveness in this high-risk population.