Focal glomerulosclerosis and maximal glomerular hypertrophy in human nephronopenia

This study examines the relationship of the degree of glomerular hypertrophy in nephronopenia to the development of focal segmental glomerulosclerosis (FGS) in humans. To this end, group mean glomerular diameters in a variety of acquired and congenital nephronopenic states in native kidneys and long-surviving renal allografts with and without FGS were analyzed and compared. The results indicate that all groups of native nephronopenic kidneys without FGS develop significant and equivalent glomerular hypertrophy. By contrast, long-surviving renal allografts without FGS do not undergo glomerular hypertrophy. For groups with FGS, long-surviving renal homografts had a significantly smaller mean glomerular diameter when compared with any other group of native nephronopenic kidneys. There was no significant difference among group mean glomerular diameters of native nephronopenic kidneys with FGS. Pairwise comparisons in each category of nephronopenia indicated that, except in the groups with uninephrectomy, the mean glomerular diameters were significantly larger in those with FGS than without. These observations are interpreted to indicate that nephronopenic individuals with native kidneys, by undergoing glomerular hypertrophy, consume much or all their capacity for glomerular enlargement. This brings them closer to their maximal diameters at which FGS develops. Finally, long-surviving renal allografts without nephronopenic FGS do not undergo glomerular hypertrophy. However, when FGS develops in long-surviving allografts, it does so at glomerular diameters significantly smaller than in native nephronopenic kidneys, reflecting their decreased capacity to undergo glomerular hypertrophy, acquiring maximal diameters at a smaller dimension than native nephronopenic kidneys.