Current guidelines recommend under 2 g/day
sodium intake in
chronic kidney disease, but there are a few studies relating
sodium intake to long-term outcomes. Here we evaluated the association of mean baseline 24-h urinary
sodium excretion with
kidney failure and a composite outcome of
kidney failure or all-cause mortality using Cox regression in 840 participants enrolled in the Modification of Diet in Renal Disease Study. Mean 24-h urinary
sodium excretion was 3.46 g/day.
Kidney failure developed in 617 participants, and the composite outcome was reached in 723. In the primary analyses, there was no association between 24-h urine
sodium and
kidney failure (HR 0.99 (95% CI 0.91-1.08)) nor on the composite outcome (HR 1.01 (95% CI 0.93-1.09)), each per 1 g/day higher urine
sodium. In exploratory analyses, there was a significant interaction of baseline
proteinuria and
sodium excretion with
kidney failure. Using a two-slope model, when urine
sodium was under 3 g/day, higher urine
sodium was associated with increased risk of
kidney failure in those with baseline
proteinuria under 1 g/day and with lower risk of
kidney failure in those with baseline
proteinuria of ⩾ 1 g/day. There was no association between urine
sodium and
kidney failure when urine
sodium was ⩾ 3 g/day. Results were consistent using first baseline and time-dependent urinary
sodium excretion. Thus, we noted no association of urine
sodium with
kidney failure. Results of the exploratory analyses need to be verified in additional studies and the mechanism explored.