Atubular glomeruli in patients with chronic pyelonephritis.

In an animal model of chronic nephropathy a large proportion of the apparently normal glomeruli have been shown to be small and without connection to a proximal tubule. The present study examines the degree to which atubular glomeruli are also present in human renal disease. Eleven patients with chronic pyelonephritis (CP) and seven controls were investigated. The number of glomeruli connected to a normal proximal tubule was determined in serial sections and the volumes of individual glomeruli estimated with stereological methods. Only glomeruli with little or no sclerosis were investigated. The volume fractions of proximal tubules and interstitial tissue were estimated using point counting. The results showed that 50% of glomeruli in the CP group were connected to a normal proximal tubule, whereas 35% of the glomeruli were without any recognizable connection to a proximal tubule (atubular glomeruli). The remaining 15% were connected to an atrophic tubule. The mean volume of the glomeruli without a connection to a normal proximal tubule was only half that of glomeruli with a normal proximal tubule. No significant difference was found between the mean glomerular volume in the two groups, but the intraindividual variation of glomerular volumes was larger in the CP group. A significant negative correlation was found in the CP group between the percentage of glomeruli without connection to a normal proximal tubule and the volume fraction of proximal tubules. A significant positive correlation was found between the percentage of glomeruli that were not connected to a normal proximal tubule and the volume fraction of the interstitial tissue. This study shows that atubular glomeruli, which only can be identified in serial sections, constitute a large proportion of glomeruli in chronic pyelonephritis. Their existence could be a major reason for the irreversibility of nonglomerular chronic renal diseases.