Low Sodium Beats Dual Blockade for Nondiabetic Nephropathy

In patients with nondiabetic nephropathy, guideline-based reductions in sodium intake are more effective than the combination of lisinopril and valsartan in lowering proteinuria and blood pressure, reports a trial in the British Medical Journal.

The randomized controlled trial included 52 outpatients with nondiabetic nephropathy. In four 6-week periods, patients were treated with the angiotensin receptor blocker (ARB) valsartan 320 mg/d or placebo (in random order) plus a low- and regular-sodium diet (in sequential order): target intake 50 versus 200 mmol Na+/d. Patients took the angiotensin-converting enzyme (ACE) inhibitor lisinopril 40 mg/d throughout the study.

Mean urinary sodium excretion was 106 mmol Na+/d on the low-sodium diet and 184 mmol Na+/d on the regular-sodium diet. Proteinuria decreased from 1.68 g/d on ACE inhibitor plus regular-sodium diet, to 1.44 with ACE inhibitor plus ARB, to 0.85 with ACE inhibitor plus low-sodium diet, to 0.67 g/d with ACE inhibitor plus ARB plus low-sodium diet. The 51 percent reduction in proteinuria with ACE inhibitor plus low-sodium diet was significantly greater than the 21 percent reduction with ARB plus ACE inhibitor.

Mean systolic blood pressure was 134 mm Hg with ACE inhibitor plus regular-sodium diet. There was a 2 percent reduction on ACE inhibitor plus ARB, compared to a 7 percent reduction with ACE inhibitor plus low-sodium diet. Adding dual blockade to low-sodium diet did not produce further significant reductions in proteinuria or blood pressure.

The results suggest that adding a low-sodium diet to an ACE inhibitor reduces proteinuria and blood pressure to a greater extent than the combination of ACE inhibitor and ARB in patients with nondiabetic nephropathy. Efforts to reduce sodium intake to recommended levels will enhance the efficacy of renoprotective strategies in this group of patients. [Slagman MCJ, et al: Moderate dietary sodium restriction added to angiotensin converting enzyme inhibition compared with dual blockade in lowering proteinuria and blood pressure: randomised controlled trial. BMJ 2011; 343: d4366].

October-November 2011 (Vol. 3, Number 10 & 11)