Acute renal insufficiency in the setting of hemolysis and thrombocytopenia, a 
triad that constitutes adult or pediatric hemolytic uremic syndrome, can be 
associated with or triggered by diverse conditions such as 
verocytotoxin-producing Escherichia coli, viral infections, pregnancy, malignant 
hypertension, scleroderma, renal radiation, allograft rejection, lupus 
erythematosus, and assorted medications such as mitomycin C, cyclosporine, and 
oral contraceptives. Recurrent and de novo hemolytic uremic syndrome occur after 
renal transplantation. Relapses are also common and probably reflect incomplete 
resolution of the initial episode. The major differential diagnoses of hemolytic 
uremic syndrome in the renal allograft include acute vascular rejection, 
cyclosporine, FK506 or antilymphocyte antibody nephrotoxicity, and malignant 
hypertension, all of which may display overlapping clinical and histologic 
features with primary hemolytic uremic syndrome; in such instances, the exact 
diagnosis may be quite difficult. It is possible that the risk of recurrence may 
be reduced by proper timing of transplantation and suitable choice of 
immunosuppressive agents. Intensive plasmapheresis in conjunction with fresh 
frozen plasma and supportive management of renal failure may lessen mortality 
and morbidity even in recurrent hemolytic uremic syndrome after transplantation.