[Incidence, etiology and prognostic value of persistent significant proteinuria in kidney transplants]

We investigated persistent significant proteinuria (PSP), defined as proteinuria > 1 gr/24 hours on three consecutive months, in renal allograft recipients. The clinical records of 273 patients (288 grafts) were reviewed and 236 grafts (178 live related, 58 cadaver donor) that functioned for at least 4 months (230 patients, 148 men and 82 women) were selected for analysis. The histological diagnoses of 226 grafts and 35 native kidneys were also reviewed. PSP was present in 67 grafts (28.4%); 43 of these grafts were studied histologically (transplant glomerulopathy (TxGPT) 19, idiopathic glomerulopathy (GP) 13, and chronic rejection 11). Patients with an idiopathic GP in the graft usually presented with the nephrotic syndrome (65%); this presentation was infrequent in patients with chronic rejection. The appearance of proteinuria was strongly associated with functional deterioration in grafts with chronic rejection and TxGPT; in grafts with PSP and a histological diagnosis of idiopathic GP, renal function was usually normal. Within grafts with PSP no statistically significant differences in actuarial survival (AS) could be established when the time of appearance or magnitude of PSP, the presence or absence of arterial hypertension, the immunosuppressive regimen, and the histological diagnosis were considered. Contrariwise, the difference in AS was highly significant (p < 0.0001) when grafts with and without PSP were compared. The former had an AS at 5 and 10 years of 74.6% and 55.7%, while in the case of the latter AS was 57.3% and 32.1%, respectively. In conclusion, in the present series 28.4% of grafts that functioned 4 months or more presented PSP. The most frequent glomerular lesion was TxGPT. The presence of PSP was a marker for poorer prognosis, since AS at 5 and 10 years was significantly less in this group.