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Glomerulonephritis is one of the diseases leading to chronic renal failure and need of renal replacement therapy. Changes in extraglomerular compartments, especially in the interstitium, are thought to play a major role in progression. However, the exact relationships between renal interstitium, tubules and vessels and their prognostic impact are less well understood. The material consisted of 111 biopsies with primary glomerulonephritis. Normal renal tissue from surgically removed kidneys served as controls. Relative interstitial volume (RIV), its variability, volume of interstitial infiltrate, cross-sectional tubular area were measured with the point-counting method. A number of vascular parameters were also measured. The assessed interstitial and tubular parameters were strongly correlated to creatinine level. The strongest correlation was seen for RIV, also on multiple regression. In patients with renal failure, increased RIV, more pronounced vascular lesions and interstitial infiltrates were seen. Survival analysis showed that interstitial expansion is the most important factor leading to renal failure. Tubulointerstitial and vascular factors are interrelated and linked to renal function. RIV has strongest impact on renal function and survival, even taking into account other factors.

The term glomerulonephritis encompass a heterogeneous group of diseases; these are a important cause of end stage renal disease. Although several evidence exist, that the main prognostic factors are extraglomerular lesions, no quantitative assessment is usually done. In nephropathological practice a semiquantitative approach is preferred. However, most of work on extraglomerular lesions significance was done with quantitative methods. The aim of the study was to compare the effects of quantitative and semiquantitative assessment of extraglomerular lesions in glomerulonephritis. The material consisted of 120 renal biopsies. On inspection, percentage of sclerosed glomeruli, degree of interstitial fibrosis, degree of interstitial infiltration, degree of tubular atrophy were and degree of mesangial matrix expansion assessed. For quantitative measurements AnalySIS 3.0 pro image analysis system was used. Relative interstitial volume, volume of interstitial infiltrate, with their variability--ross sectional areas of proximal and distal tubules were assessed by point counting method. Relative interstitial volume was significantly correlated to percentage of sclerosed glomeruli (R = 0.33 p < 0.001), degree of tubular atrophy (gamma = 0.57 p < 0.00001), degree interstitial fibrosis (gamma = 0.31 p < 0.0002) and mesangial matrix expansion (gamma = 0.24 p < 0.001). Semiquantitative and quantitative assessment of interstitial infiltrate was significantly correlated as well (gamma = 0.81 p < 0.001). Semiquantitatively assessed degree of tubular atrophy showed significant relation to total proximal tubular area (gamma = -0.30 p = 0,004). Percentage of sclerosed glomeruli was significantly correlated to creatinine level (R = 0.24 p = 0.03), but not to urea level (R = 0.09, NS). Semiquantitatively assessed degree of interstitial fibrosis showed only marginal correlation to creatinine level (gamma = 0.18 NS), however degree of interstitial infiltration was significantly correlated to creatinine (gamma = 0.34 p = 0.002) and urea level (gamma = 0.22 p = 0.06). Degree of tubular atrophy was significantly correlated to creatinine (gamma = 0.43 p < 0.001) and urea level (gamma = 0.28 p = 0.015). Relative interstitial volume was the very most important correlate of creatinine (R = 0.47 p < 0.0001) and urea level (R = 0.30 p < 0.01). In conclusion, it was confirmed, that the strongest correlate of renal function is relative interstitial volume. Some, but not all of semiquantitative parameters are also significantly correlated to kidney function.