A multicenter study of IgA nephropathy in children. A report of the Southwest Pediatric Nephrology Study Group.

Clinical and pathologic features of IgA nephropathy were evaluated in 62 children (age range, 4 to 18 years; 46 boys, 16 girls) in a collaborative study carried out by members of the Southwest Pediatric Nephrology Study Group (SPNSG). Microscopic hematuria was present in all of the patients prior to renal biopsy and was associated with gross hematuria in 85%, proteinuria (greater than or equal to 2+) in 48%, hypertension in 6%, and depressed GFR in 25% of the patients. Renal biopsy specimens were reviewed and classified into three groups on the basis of light microscopy (LM): (1) normal glomeruli (16 patients), (2) mesangial hypercellularity (25 patients), and (3) focal and segmental proliferative and/or sclerosing glomerulonephritis (21 patients). Tubulo-interstitial changes, which were present in 56% of the biopsy specimens, showed no correlation with the duration of clinical disease. Peripheral glomerular capillary wall changes shown by electron microscopy (EM) were present in 40% of the biopsy specimens and were associated with more severe glomerular changes revealed by LM. Proteinuria and episodes of gross hematuria were associated with more severe histologic changes (group 3) and peripheral capillary wall changes demonstrated by EM. Mild patterns of glomerular damage (groups 1 and 2) were associated with female sex. The studies show that evidence of tubulo-interstitial damage and peripheral glomerular capillary wall changes are not uncommon in children with IgA nephropathy and suggest that these features may be harbingers of a more serious prognosis than previously thought.