There is large interindividual variability in the antiproteinuric response to blockade of the renin-angiotensin-aldosterone system (RAAS). A
low-sodium diet or addition of
diuretics enhances the effects of RAAS blockade on
proteinuria and BP, but the efficacy of the combination of these interventions is unknown. Therefore, this randomized, double-blind, placebo-controlled trial to determine the separate and combined effects of a
low-sodium diet and
hydrochlorothiazide (HCT) on
proteinuria and BP was performed. In 34 proteinuric patients without diabetes, mean baseline
proteinuria was 3.8 g/d, and this was reduced by 22% by a
low-sodium diet alone.
Losartan monotherapy reduced
proteinuria by 30%, and the addition of a
low-sodium diet led to a total reduction by 55% and the addition of HCT to 56%. The combined addition of HCT and a
low-sodium diet reduced
proteinuria by 70% from baseline (all P < 0.05). Reductions in mean arterial pressure showed a similar pattern (all P < 0.05). In addition, individuals who did not demonstrate an antiproteinuric response to
losartan monotherapy did respond when a
low-sodium diet or a
diuretic was added. In conclusion, a
low-sodium diet and HCT are equally efficacious in reducing
proteinuria and BP when added to a regimen containing
losartan and especially seem to benefit individuals who are resistant to RAAS blockade. Combining these interventions in
sodium status is an effective method to maximize the antiproteinuric efficacy of RAAS blockade.