Hyponatremia Increases Hospital Stays, Mortality for Cancer Patients

Cancer patients with hyponatremia have longer hospital stays and increased mortality, a new study finds. The study, which involved retrospective analysis of prospectively collected data on frequency of hyponatremia in patients with cancer and its impact on their clinical outcomes, was published online last month in the American Journal of Kidney Diseases.

The study’s participants were cancer patients admitted to the University of Texas M.D. Anderson Cancer Center over a three-month period in 2006. Patients were categorized as having eunatremia (serum sodium of 135-147 mEq/L), mild hyponatremia (130-134 mEq/L), moderate hyponatremia (120-129 mEq/L), or severe hyponatremia (<120 mEq/L). The study looked at 4,702 admissions with 3,357 cancer patients. Hyponatremia (i.e. serum sodium <135 mEq/L) was noted in 47% of admissions—mild in 36%, moderate in 10%, and severe in 1%. In 24% of admissions, hyponatremia was acquired during the hospital stay. Outcomes investigated were length of hospital stay and 90-day mortality.

Mean length of hospital stay was 5.6 days for those with eunatremia, 9.9 days for those with mild hyponatremia, 13.0 days for those with moderate hyponatremia, and 11.5 days for those with severe hyponatremia. Hazard ratios for longer hospital stay, with eunatremic patients as a reference, were 1.92 for those with mild hyponatremia, 2.94 for those with moderate hyponatremia, and 2.32 for those with severe hyponatremia. 283 deaths occurred during the study period, and hazard ratios for 90-day mortality were 2.04 for those with mild hyponatremia, 4.74 for those with moderate hyponatremia, and 3.46 for those with severe hyponatremia.

“Hyponatremia in patients with cancer is associated with longer hospital stay and higher mortality,” the researchers write. “Whether long-term correction of hyponatremia would improve these outcomes remains to be determined.”