ADDITIVE ANTIPROTEINURIC EFFECT OF ACE-INHIBITION AND A LOW-PROTEIN DIET IN HUMAN RENAL-DISEASE

Both ACEi and a low-protein diet (LPD) are reported to reduce urinary protein excretion in patients with stable non-diabetic renal disease. To test whether the combination of both may have an additive antiproteinuric effect, we studied the effects of single treatment with ACEi (10 mg enalapril o.d.), LPD (target, 50% reduction in protein intake), and the combination of both in 14 of such patients with stable proteinuria exceeding 3 g per day. Baseline measurements were performed while patients were on a normal protein diet (NPD). In group A (n=7), first the effects of a LPD were investigated, whereafter the effects of addition of ACEi to LPD were studied. In group B (n=7), first the effects of ACEi were investigated, whereafter the effects of addition of a LPD to ACEi were studied. Each treatment period lasted 2 months. LPD decreased proteinuria with 17% in patients without ACEi treatment (group A), and similarly with 19% in patients with ACEi treatment (group B). The antiproteinuric response obtained with the LPD in individual patients ranged from -63% to +1%. This variation is at least partly explained by interindividual differences in diet compliance, since the antiproteinuric effect of the LPD was found to correlate with the achieved reduction in protein intake (r=0.58, P<0.05). ACEi lowered proteinuria with 32% during the NPD (group B), and similarly with 43% during the LPD (group A). The combination of ACEi and LPD decreased proteinuria significantly more than each single treatment: proteinuria fell by 55% compared to baseline when ACEi was added to LPD (group A), and by 49% when LPD was added to ACEi (group B). In conclusion, both ACEi and LPD lower urinary protein excretion. The combination of both regimens reduces proteinuria significantly more than each single treatment. These results may be of value in the symptomatic treatment of proteinuric patients.