Limiting Sodium to Ward Off Kidney Stones

August 31/Cheongju, South Korea/Reuters Health Medical News -- Despite some recent contradictory findings, South Korean investigators conclude that a sodium-restricted diet is important in reducing the risk of recurrence in patients prone to develop urinary stones.

Dr. Sang-Cheol Lee and colleagues at Chungbuk National University in Cheongju, South Korea, report their findings in the October Journal of Urology.

They note that sodium restriction is a common recommendation for patients with recurrent urinary stones, with the aim of reducing urinary sodium and thereby modulating urinary volume, pH and other determinants of stone formation. However, the utility of this strategy has been questioned in several studies.

The researchers looked at the recurrence rate in 798 patients with a history of stone formation according to urinary sodium levels. The subjects were classified into 455 with normal natriuresis and 343 with hypernatriuresis.

Urine sodium significantly correlated with BMI, urine volume, pH, calcium, uric acid, oxalate and citrate, according to the report.

The analysis of stone recurrence included 191 of the subjects. After a median follow-up of 56 months, urinary stones recurred in 46.9% of subjects with normal natriuresis compared with 64.5% of those with hypernatriuresis (p=0.043), Dr. Lee and colleagues found.

"Thus, we suggest that sodium restriction should be the first step in preventive therapy for urinary stone disease," they conclude, "Our results should interest urologists since decreased dietary sodium can be immediately, safely and easily applied in stone formers to decrease the risk of recurrent stones."

SOURCE: J Urol 2010;194:1372-1376.

From the September 7, 2010, Prepared Foods E-dition