Low serum bicarbonate is a strong predictor of mortality among adults with chronic kidney disease (CKD), new findings suggest.

Kalani L. Raphael, MD, of the University of Utah School of Medicine in Salt Lake City, and collaborators analyzed data from 15,836 adults who participated in the National Health and Nutrition Examination Survey III. They placed subjects into one of four serum bicarbonate categories: less than 22, 22-25, 26-30, and 31 mM or greater.

After adjusting for age, gender, race, estimated glomerular filtration rate, and numerous other potential confounders, subjects with CKD who had a bicarbonate level below 22 had a nearly 2.6 times increased risk of death compared with those who had a level of 26-30 (reference category), the investigators reported in Nephrology Dialysis Transplantation (2013;28:1207-1213). The finding is consistent with previous studies, the researchers noted.

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Among subjects without CKD, those with bicarbonate levels below 22 had a 56% increased risk of death compared with the reference category, but this did not reach statistical significance. “It is plausible that statistical significance was not achieved because there wree few deaths in the non-CKD category, which limited statistical power,” the authors wrote.