Low Glomerular Density with Glomerulomegaly in Obesity-Related Glomerulopathy

Background and objectives Obesity-related glomerulopathy is a secondary form of glomerular disease that may occur in obese individuals. It is histologically characterized by marked glomerulomegaly closely related to glomerular hyperfiltration. This study examined glomerular density (nonsclerotic glomerular number per renal cortical area of biopsy specimen) in patients with obesity-related glomerulopathy to determine whether any differences in this measure is associated with disease status. Design, setting, participants, & measurements Glomerular density and glomerular volume in renal biopsy samples from patients with obesity-related glomerulopathy were compared with those of kidney transplant donors and patients with IgA nephropathy. Kidneys obtained from persons without renal diseases during autopsy were also analyzed to investigate the effects of obesity on glomerular density and glomerular volume. Results Glomerular density of kidneys from patients with obesity-related glomerulopathy (1.71 +/- 0.6/mm(2)) was significantly lower than that in biopsy samples from kidney transplant donors (3.1 +/- 1.0/mm(2)) and patients with IgA nephropathy (3.5 +/- 1.5/mm(2)). However, an analysis of autopsy cases without renal diseases showed that the glomerular density in overweight (2.9 +/- 0.7/mm(2)) or obese (3.1 +/- 1.1./mm(2)) persons was similar to that in non-obese (3.1 +/- 0.6/mm(2)) individuals. Biopsy specimens of patients with obesity-related glomerulopathy showed marked glomerulomegaly. However, glomerular volume was only modestly increased in the autopsy-examined kidneys from overweight or obese persons without renal diseases. Conclusions Low glomerular density associated with glomerulomegaly may be a characteristic histologic finding of patients with obesity-related glomerulopathy. Clin J Am Soc Nephrol 7: 735-741, 2012. doi: 10.2215/CJN.07270711