Long-term prognosis of IgA nephropathy presenting with minimal or no proteinuria: A single center experience

The long-term prognosis of patients with IgA nephropathy (IgAN) who present with preserved renal function and minimal proteinuria is not well described. We investigated the long-term outcomes of IgAN patients with an apparently benign presentation and evaluated prognostic factors for renal survival and clinical remission. We studied Japanese patients with biopsy-proven IgAN who had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) and proteinuria <0.5 g/day at the time of renal biopsy. The renal biopsies were reviewed using the Oxford classification. Twenty patients met the inclusion criteria. At diagnosis, the median eGFR (interquartile range) was 76.8 (65.2-91.1) mL/min/1.73 m(2), and the median proteinuria level was 0.31 (0.16-0.39) g/day. Only one patient had an increase in serum creatinine of over 50% and no patient progressed to end-stage renal disease. The 15-year renal survival rate was 93.8%. Clinical remission was observed in 9 (45%) patients. Baseline proteinuria was the only factor significantly associated with the absence of clinical remission. The long-term prognosis of Japanese patients with IgAN who presents with minor urinary abnormalities and preserved renal function is excellent.