Dietary protein manipulation in experimental nephrotic syndrome

Evidence that glomerulosclerosis may be accelerated by high-protein diet and ameliorated by low-protein diet has led to debate concerning appropriate dietary recommendations in nephrotic syndrome. In this study, dietary protein was manipulated in a chronic, non-uraemic experimental model of nephrotic syndrome. Groups of 12 AS rats received 12, 24 or 48% protein diet after nephrotic syndrome was induced by adriamycin. Animals were sacrificed 8 weeks after change of diet when all were normotensive and none were uraemic. Animals on 24 and 48% maintained initial body weight and had persistent nephrosis. There was renal hypertrophy and histology showed tubular casts, focal tubulo-interstitial injury and glomerulosclerosis. Animals on 48% diet had more renal hypertrophy and worse histological damage but no differences in other parameters compared to 24% diet. On a 12% protein diet animals lost 15 +/- 3% of initial body weight (from 221 +/- 6 to 188 +/- 6 g; p less than 0.001). There was less proteinuria (p less than 0.0001), and lower serum cholesterol (p less than 0.0001) and triglyceride (p less than 0.01). Serum albumin was not different but total protein was lower than on 24 and 48% diet (p less than 0.01). Renal histological damage, although less severe than on 48% diet, did not differ from 24% diet. There was fatty infiltration of the liver. In view of the effects of low-protein diet in this model of nephrotic syndrome, dietary protein restriction should be applied with caution in human nephrotic syndrome.