Hyponatremia (HN), defined as a serum sodium lower than 135 mmol/l, is the most common electrolyte disorder in hospitalized patients. Etiology is heterogeneous and a large difference exists in terms of symptoms and treatments. The aim of this study is to determine the incidence of HN in a Tertiary Cancer Center evaluating possible influence in terms of prognosis and length of hospitalization.
This study includes all cancer patients hospitalized at our Institution from January 2015 to December 2015 for all causes otherwise than HN. We analyzed retrospectively data regarding HN and correlation to age, sex, staging, histology. Survival distribution was estimated by Kaplan-Meyer method, differences in probability of surviving were evaluated by chi-square test.
A total of 1.071 patients were included in the analysis. 243 (22.7%) presented at least one episode of HN; 197 (81.1%) showed mild hyponatriemia (135-130 mmol/l), 44 (18.1%) moderate (130-125 mmol/l), 2 (0.8%) severe (< 125 mmol/l). Patients were affected by lung cancer in 21.7%, breast cancer in 19.5%, colorectal cancer in 13.0% (others in 45.8%). Most patients had Stage IV disease (93.4%), male 44.7%, female 54.3%. Median age was 62.9 years. Concomitant diagnosis of SIADH was performed in 4 patients (8.8%). Resolution of HN after specific treatments was observed in 19 patients (41.3%), without significant differences about length of hospitalization between patients with normal and abnormal value at discharge. OS was lower in patients with moderate/severe HN versus mild (2.72 vs 6.81 months). Mortality rate was significantly lower in patients with corrected HN compared to not (52.6 vs 81.5%; p: 0.08), while no statistically significant difference was observed in OS (2.89 vs 2.63 months; p: 0.85).
HN represents a frequent occasional finding in hospitalized cancer patients, although in most cases it's of mild degree. SIADH represents a small percentage of cases. In our experience HN is not associated to discharge delays. Independently by the underlying disease, moderate and severe HN identify a particular group of patients with poor prognosis, probably reflecting very advanced disease and palliative care needs.
Clinical trial identification
Legal entity responsible for the study
Fondazione IRCCS Istituto Nazionale dei Tumori
All authors have declared no conflicts of interest.