Restricted protein diet is associated with decrease in proteinuria: Consequences on the progression of renal failure

Objective: Reduction of proteinuria is associated with a slower progression of renal failure. We questioned whether the change in proteinuria in response to a supplemented very low protein diet (SVLPD), which is known to reduce proteinuria, could function as a marker of the potential renoprotective effect of an SVLPD. Design and Patients: In the 220 consecutive patients of our previously published cohort, the glomerular filtration rate (GFR) was assessed every 3 months using the Cr-51-EDTA method. Seventy-eight patients (mean age 52 +/- 17 years, body mass index 23 +/- 3 kg/m(2), GFR 15 +/- 6 mL/min) exhibited a proteinuria more than 1 g per day at the start of the regimen. Mean protein intake assessed by urinary nitrogen appearance was 0.42 +/- 0.24 g/kg per day at 4 months. The median follow-up was 24 months. Results: Proteinuria decreased significantly after patients were treated with an SVLPD. The maximum mean percent reduction was attained at 3 months (47% +/- 27%), was not influenced by the levels of baseline proteinuria, and was similar in patients receiving or not receiving angiotensin-converting enzyme inhibition at the start of the study. The percent reduction and the residual proteinuria at 3 months predicted the rate of the later GFR decline. GFR decline was significantly lower in patients whose reduction in proteinuria at 3 months was higher than 50% (0.42 +/- 0.37 mL/min/mo vs. 0.10 +/- 0.15 mL/min/mo and 1.0 +/- 0.6 mL/min/mo vs. 0.15 +/- 0.19 mL/min/mo, P <.001 in patients with proteinuria higher or lesser than 3 g/d at start, respectively). Conclusion: These results do not differ from those reported with therapies antagonizing angiotensin 11 formation and/or activity aiming at reducing proteinuria in chronic renal diseases. (C) 2007 by the National Kidney Foundation, Inc.