Continued Anticomplement Therapy: A Lifeline for Post-Renal-Transplant Patients with Complement-Mediated Hemolytic Uremic Syndrome

Abstract

Background: Complement-mediated hemolytic uremic syndrome (CM-HUS), formerly known as atypical HUS, is a rare but potentially fatal thrombotic microangiopathy (TMA) characterized by the triad of thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and acute kidney injury. It is primarily caused by complement dysregulation. The condition can progress to end-stage renal disease (ESRD), often necessitating kidney transplant. In rare instances, it can develop in post-renal-transplant patients. Methods: Here, we present the cases of two patients with ESRD status post kidney transplant who presented with thrombocytopenia, anemia, and acute kidney injury. In both cases, work-up was suggestive of CM-HUS, and stabilization was achieved with eculizumab. Discussion: The pathogenesis of CM-HUS involves dysregulation of the complement system, and complement inhibitors such as eculizumab can be used for initial management and relapse. The relapse rate following eculizumab treatment can range from 20 to 67%. Patients with a history of kidney transplant are more prone to relapse than those with native kidneys. Re-treatment with complement inhibitors has proven effective in managing relapses, and long-term continuation of complement inhibitor medications is recommended to prevent recurrence. Conclusions: CM-HUS is rare, especially in post-transplant patients, and can be potentially fatal. It is crucial for clinicians to recognize and treat this condition promptly. Management often involves complement inhibitors. The risk of relapse is particularly high in patients with a history of kidney transplant, but long-term continuation of these medications can prevent relapse.