Clinicopathological Correlation of IgA Nephropathy in Children

22 patients with IgA nephropathy aged 7–16 years, 15 of whom were found by mass urine screening of school children, were divided into three groups based on the degree of their proteinuria at admission: group A (n = 6) below 0.5 g/day of urine protein, group B (n = 7) between 0.6 and 3.0, and group C (n = 9) above 3.0 g/day of urine protein. The degree of proteinuria seemed to be related to the severity of pathological changes of the glomerular basement membrane; most severe in group C, moderate in group B, and minimal in group A. IgA deposits in the mesangial area were found in all groups of patients, but those in the capillary walls were most frequently found in group C. In addition to electron-dense deposits in the mesangial area, which was found in all groups of patients, the subendothelial and subepithelial deposits were the most remarkable changes found in group C. During the clinical observation period, which was between 2.0 and 7.1 years, no patient belonging to group A progressed to groups B or C. 4 cases in group C developed chronic renal failure, but none in the other groups did. The amount of urine protein might be used as a valuable parameter of the pathological damage of the glomerulus in children with IgA nephropathy.