A clinicopathological study of adult Japanese IgA nephropathy patients: Early stage cases and cases with exacerbation

Summary: Most cases of adult type IgA nephropathy (IgAN) have an insidious onset and asymptomatic course. However, some patients reveal recurrent macroscopic haematuria following episodes of respiratory or urinary tract infections. In order to clarify the correlation between clinical features and histological alterations or prognosis, 42 cases of early stage IgAN and 40 cases with acute exacerbation episodes were investigated and compared with a control group. Early stage cases were defined as having had a renal biopsy within 1 year after the first detection of urinary abnormalities, and had normal urinary findings within the 12 months before the first detection of urinary abnormalities. Acute exacerbation cases were defined as macroscopic haematuria or worsening of urinary abnormalities after acute infectious episodes and undergoing a renal biopsy within 120 days after the onset of these episodes. the early stage cases had better renal function and lower systolic and diastolic blood pressure than that of control group. They also showed milder changes in mesangial cell proliferation, mesangial matrix increase, totally sclerotic glomeruli, and tubulo-interstitial changes. However, it is important to note that glomerular and interstitial sclerotic changes were observed even in early stage cases. Endothelial detachment was noticed more frequently in the early stage cases. Acute exacerbation cases revealed lesions of endocapillary proliferation, mesangiolysis and endothelial detachment more frequently, although these changes were segmental in each glomerulus. There was no statistical difference in disease prognosis between cases with and without acute exacerbation. These data indicated that there are characteristic histological changes in early stage cases and acute exacerbation cases of IgAN.