Background: It has been proposed that, once renal function has been restricted in chronic kidney disease, compensatory hyperfiltration results in a compulsory deterioration of renal function.
Patients and methods: In this study, 83 patients originally starting from a serum creatinine (S(crea)) between 2.0 and 5.0 mg/dl were followed for the evolution of renal function. This overall population, with a follow-up (FU) of(M +/- SD) 67 +/- 50 months, was stratified into two groups based upon their slope of 1/S(crea), whereby the median of this slope (-0.0019) was taken as the cut-off value.
Results: There was an expected decline of renal function in the group with the lowest slope (group A = progression) whereas renal function remained stable in the group with the highest slope (group B = no progression). This evolution occurred in spite of a similar S(crea) in both groups at the start of the study (group A: 2.45 +/- 0.71 mg/100 ml (n = 41) vs. group B: 2.94 +/- 0.88 mg/100 ml (n = 42); p = ns) and an even higher creatinine clearance in group A (group A: 46.43 +/- 18.65 mg/100 ml(n = 41)vs. group B: 34.03 +/- 20.11 mg/100 ml (n = 42); p = 0.0049). Group B contained a higher number of patients with interstitial nephritis (34/42 = 81% vs. 6/41 = 15%; p < 0.00001) while patients with chronic glomerulopathy could be found especially in group A (23/41 = 56% vs. 8/42 = 19%; p < 0.00001). Proteinuria was continuously higher in group A (start FU: p = 0.0097; FU 72 months: p = 0.0155) and tended to decrease in group B (start FU, 0.89 +/- 1.42 g/l (n = 42) vs. FU 72 months, 0.41 +/- 0.78 g/l (n = 26); p = 0.0474) whereas no significant decrease was observed in group A (start FU, 2.16 +/- 2.83 g/l (n = 41) vs. FU 72 months, 1.77 +/- 0.72 g/l (n = 6); p = ns).
Conclusion: Within the time limit and patient inclusion criteria of this FU, a compromised renal function does not necessarily result in a further decline. This study points more towards a major role for the underlying nature of renal disease.