Interstitial, tubular and vascular factors in progression of primary glomerulonephritis.

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.