What is the most common cause of proteinuria post renal transplantation?
By far, the most common cause of proteinuria post transplant as you all rightly suggested is chronic allograft failure leading to scarring and protienuria. Recurrent and denovo GN can be the remaining cases. Diabetic nephropathy is not uncommon but others are more likely to get biopsied and reported. Viruses such as parvovirus B19 can lead to collapsing FSGS, CMV can lead to FSGS. It is important to note that in those studies the classification of allograft pathology deviated from the Banff classification in that the diagnostic term “chronic allograft nephropathy” excluded allografts with any type of glomerular pathology, except global glomerulosclerosis. Hence, some forms of allograft glomerular pathology, such as transplant glomerulopathy, may be associated with CAN but it has distinct pathogenesis, clinical presentation and prognosis( and degree of antibody mediated response). In addition, other forms of de novo glomerular disease, such as focal segmental glomerulosclerosis, are rarely present in patients with CAN and when present defines a subgroup of patients with a distinct clinical presentation and prognosis. Finally certain drugs such as sirolimus have been associated with proteinuria and FSG as well.