Calcific Changes in an End-Stage Kidney following Long-Term Dialysis, Tertiary Hyperparathyroidism, and Treatment for Complement-Mediated Thrombotic Microangiopathy: A Case Report.

Introduction: There are few descriptions of glomerular calcification in patients with advanced or end-stage kidney disease (ESKD). There also are limited data on long-term outcomes for patients receiving complement factor 5 inhibitor (C5i) treatment for complement-mediated thrombotic microangiopathy (CM-TMA), previously termed atypical hemolytic uremic syndrome, associated with a complement factor I (CFI) mutation. Case Presentation: Here we report a case of ESKD from CM-TMA in a patient who developed tertiary hyperparathyroidism. Due to cerebral symptoms (focal paresthesias) of TMA, he received long-term treatment with a C5i. A nephrectomy subsequently was performed for renal cell carcinoma and showed diffuse glomerular, in addition to focal arterial and tubular basement membrane, calcification. There also was chronic TMA associated with continued C5i treatment, with no evidence of recurrent thrombosis consistent with quiescent systemic TMA activity. Conclusion: Glomerular calcification is rare, and it is unknown if this is related to the treated hyperparathyroidism or other pathogenetic mechanisms. The nephrectomy findings also suggest that patients with pathogenic mutations in CFI may benefit from long-term, likely lifelong, complement inhibitory treatment.