[Relation between creatinine clearance and glomerular filtration in various stages of chronic renal disease]

The relationship between creatinine clearance (Ccr) and inulin (C(in)) was investigated in 20 healthy subjects (group A) and 54 subjects with chronic renal disease (C(in): 10-80 ml/min/1.73 m2) treated conservatively (group B) and in 10 subjects with regular dialyzation treatment and a preserved residual diuresis (more than 1000 ml/24 h) (group C). In subjects from group B the Ccr/C(in) values were significantly higher than in healthy subjects (p < 0.01). In subjects of group C the values of Ccr/C(in) before dialysis did not differ significantly from values recorded in healthy subjects. Twelve hours after dialysis a marked increase of C(in)/Ccr occurred (p < 0.001). The findings are consistent with the idea that the increase of tubular creatinine secretion in patients with chronic renal disease is associated with a rise of its plasma concentration. In terminal stages in chronic renal failure there is, however, again a drop of tubular creatinine secretion which is reversible and rises after dialysis. These changes in tubular creatinine secretion could be explained by the fact that in chronic renal failure substances cumulate in the organism which inhibit tubular creatinine secretion. Due to haemodialysis the concentration of these inhibitors of creatinine secretion declines and after dialysis this process increases again temporarily. The findings suggest that the residual Ccr value assessed before dialysis is closer to the real value of glomerular filtration than values assessed during dialysis.