The influence of glomerular and interstitial factors on the serum creatinine concentration in renal amyloidosis.

48 cases of renal amyloidosis (grade I-IV) were investigated morphologically (point-counting method). Statistically significant positive correlations exist between relative interstitial volume and serum creatinine concentration at the time of biopsy. In amyloidosis there are furthermore connections (positive rank correlations) between the extent of glomerular amyloidosis and renal insufficiency, although single cases of grade III show normal serum creatinine concentrations if the interstitium is not enlarged. With regard to interstitial alterations only fibrosis, not amyloid masses, seems to influence renal function, especially in the case of predamaged glomeruli (grade II to IV). The diminished renal function - reduction of the glom. filtr. rate - may be explained in the case of interstitial fibrosis by slowing of renal blood flow caused by a decreasing cross-sectional area of postglomerular vessels. Renal insufficiency seems to depend upon both the glomerular and the interstitial factor, but in grades II-IV the interstitial fibrosis is thought to be of more importance for renal function.