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 ⁵¹Cr-EDTA method. Seventy-eight patients (mean age 52 ± 17 years, body mass index 23 ± 3 kg/m², 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 II formation and/or activity aiming at reducing proteinuria in chronic renal diseases.