Renal insufficiency in nephrosclerosis (benign nephrosclerosis resp. transition from benign to secondary malignant nephrosclerosis) correlations between morphological and functional parameters

Abstract

62 tissue specimens with the only diagnosis benign nephrosclerosis (or benign nephrosclerosis with transition to secondary malignant nephrosclerosis) were investigated attempting to correlate morphological findings (relative interstitial volume of the renal cortex, types of hyalinisation and kinds of periglomerular changes, vessel index) with each other and with the serum creatinine concentration as a parameter of renal function. There are significant correlations in form of exponential and parabolic functions between relative interstitial volume of the renal cortex and the serum creatinine concentration at the time of biopsy. Furthermore 5 types of glomerular and periglomerular changes, which could be discriminated, seem to influence renal function in a different way and at different stages of the disease. An additional factor are the arteriolar changes. There are positive rank correlations between vessel index and serum creatinine concentration as well as between vessel index and relative interstitial volume. In cases with a higher percentage of hyalinized glomeruli more pronounced arteriolar lesions (partly alterations which can be found in secondary malignant nephrosclerosis) were observed. No connections seem to exist between mean blood pressure and the mentioned morphological and functional parameters. The reduction of renal function seems to be caused by tubular and interstitial factors: the often observed atrophy of tubules in fibrotic areas possibly impairs resorptional capacity. The mechanisms of the glomerular-tubular-balance may lead to a diminished glomerular filtration. On the other hand alterations of the capillaries may induce perivascular edema, which, if not reabsorbed, leads to interstitial fibrosis. The produced collagen fibres may reduce the cross sectional area of the postglomerular vessel network. This may lead to a slowing of the renal cortical and glomerular blood flow, thus inducing an increase of the serum creatinine concentration. Weighing all factors, the interstitial fibrosis seems to be the most important.