Clinical and pathological studies of IgA nephropathy presenting as a rapidly progressive form of glomerulonephritis.

OBJECTIVE: IgA nephropathy (IgAN) is widely regarded as a slowly progressive disease. However, a minor population of patients present with a rapidly progressive form of glomerulonephritis (RPGN). METHODS: We studied 25 cases of IgAN who presented with RPGN. The laboratory data, histology, and five-year prognosis after diagnostic renal biopsy were evaluated. We compared the data of these patients with those of 495 patients with the non-RPGN type. In addition, we divided the patients with the RPGN type of IgAN into a group with reduced renal function and a group with maintained renal function, and compared the data between the two groups. RESULTS: In the 'RPGN type', the serum creatinine levels and a 24-hour urinary protein excretion were significantly higher than in the non-RPGN type. Histological examinations showed that the rates of endocapillary hypercellularity and tubular atrophy/interstitial fibrosis were significantly higher in the patients with the RPGN type. In the comparison between the groups with reduced and maintained renal functions, the former group exhibited higher levels of proteinuria, serum creatinine and crescent formation than the latter group. CONCLUSION: The RPGN type of IgAN was significantly worse in terms of the renal survival rate at five years than the non-RPGN type. Intensive and active treatments are necessary for this minor population, according to the guideline for the management of RPGN.