SAN DIEGO—Hyponatremia has been linked with poor outcomes in chronic kidney disease (CKD) patients. Now researchers presenting at Kidney Week reveal that a related electrolyte abnormality, low serum chloride levels, is also associated with adverse outcomes.

Shintaro Mandai, MD, of Tokyo Medical and Dental University in Japan, and colleagues examined cardiovascular events and all-cause mortality in 923 pre-dialysis CKD patients (stages 2–5) from the CKD Research of Outcomes in Treatment and Epidemiology (CKD-ROUTE) study. The primary outcome was a composite of death from any cause and cardiovascular events.

During a median 33 months of follow-up, there were 98 cardiovascular events, 66 deaths, and 154 composite outcomes.

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The risk of the composite outcome was 72% higher for patients in the first chloride quartile (103.9 mEq/L and below) than for patients in the third quartile (106-108 mEq/L). The risk of death from any cause was 2.5 times greater for these same patients.

When investigators examined chloride levels as a continuous variable in patients at or below the median of 106 mEq/L, they discovered that having chloride levels on the higher end of the range was linked with a 7% lower risk of adverse outcomes. The researchers adjusted their results for serum sodium levels and other potential confounders.

“Low chloride may be an additional predictor of adverse outcomes in CKD,” Dr. Mandai told Renal & Urology News. “A measurement of serum chloride level is routinely available on biochemical tests in clinical practice, and thus clinicians should direct much attention to this value as a prognostic indicator in CKD patients.”