Correcting hyponatraemia is associated with improved survival in hyponatraemic metastatic cancer patients

Background Hyponatraemia in cancer patients admitted to the hospital is associated with longer stays, higher costs and increased mortality. We examined the impact of hyponatraemia correction on survival in hospitalized patients with advanced cancer. Methods We reviewed records of patients with solid tumours who were hospitalized between January 2018 and December 2022 with serum sodium ≤125 mEq/l at admission. Cox regression analysis examined associations of demographic and clinical characteristics, including sodium levels at admission and discharge, with overall survival. Results Among 1100 patients, median sodium levels were 122 mEq/l at admission and 132 mEq/l at discharge. A total of 165 patients (15%) died during hospitalization and 414 of 688 discharged home (60.2%) died within 5 years. Multivariable analysis showed that among patients discharged alive, a decrease in sodium from admission to discharge (P = .0081), sodium ≤125 mEq/l at discharge [hazard ratio (HR) 1.42; P = .0382], albumin <3.5 g/dl at admission (HR 1.48; P < .0001), metastatic stage (HR 1.37; P = .0004), emergency admission (HR 1.20; P = .0390), discharge to hospice (HR 2.57; P < .0001), lung cancers (HR 1.51; P = .0044) and metastatic disease (HR 1.37; P = .0004) were associated with poorer overall survival. Sodium level at admission was not a significant predictor of overall survival from hospital admission. In patients with metastatic disease, an increase in sodium from admission to discharge was associated with improved overall survival from hospital discharge. Conclusions Correcting hyponatraemia in hospitalized patients with metastatic cancer increases overall survival, but metastatic cancer in itself is also associated with poor survival. This highlights the importance of early palliative care involvement in patients with advanced cancer.