Causes of Acute Thrombotic Microangiopathy in Patients Receiving Kidney Transplantation

Abstract

Objectives: Thrombotic microangiopathy is a well-known problem in patients following renal transplantation. In postrenal transplantation, thrombotic microangiopathy is often a reflection of hemolytic uremic syndrome. We aimed to determine the causes of thrombotic microangiopathy in a population of renal transplantation recipients and discuss the literature.

Materials and Methods: We investigated the causes of thrombotic microangiopathy during a 1year period, from June 2003 to June 2004, at the King Fahad National Guard Hospital in Riyadh, Saudi Arabia, by reviewing the slides of all transplant biopsies (n = 25) performed during this interval. Pre- and posttransplant crossmatching was done when possible.

Results: Five cases of thrombotic microangiopathy were found. Three of these cases were from the 25 transplantations performed at King Fahad National Guard Hospital, while the other 2 transplantations had been performed abroad and were referred to us for follow-up. Three cases were related to cyclosporine, and 1 case was secondary to both cyclosporine and tacrolimus. The fifth case had features of thrombotic microangiopathy related to an antiphospholipid syndrome in a patient with systemic lupus erythematosus.

Conclusions: In the literature, the most-frequent cause of hemolytic uremic syndrome in patients following renal transplantation is recurrence of the hemolytic uremic syndrome. Other causes include drug-related (cyclosporine, tacrolimus) toxicity, procoagulant status, and antibody-mediated rejection. We found that the most-frequent cause of thrombotic microangiopathy was drug related, secondary mainly to cyclosporine. In the current study, the frequency of thrombotic micro-angiopathy was similar to the percentage reported in the literature (20%).