Prognosis of Cancer Patients with Severe Hyponatremia in the Emergency Department: A Retrospective Study from the National Cancer Center of China.

Aim: The aim of this study was to analyze the clinical characteristics and prognostic factors of profound hyponatremia in solid cancer patients admitted to the oncologic emergency department.

Methods: We gathered data retrospectively from cancer patients who visited the emergency department of the National Cancer Center of China between October 2019 and February 2023 with a serum sodium (Na) level of less than 125 mmol/L. The demographic and clinical characteristics, medical history, admission symptoms, laboratory parameters, and outcomes of the patients were recorded.

Results: This study comprised 307 patients with severe hyponatremia in total. With 39.4% of all tumors being lung cancer (n = 121), nausea and vomiting were the most common admission symptoms for patients with severe hyponatremia. The 30-day mortality rate of profound hyponatremia cancer patients in the emergency department was 13.4%. The albumin level (p < 0.001), the hemoglobin level (p = 0.033), the TNM stage (p = 0.004), the Eastern Cooperative Oncology Group Performance Status (ECOG-PS) score (p < 0.001), hypocalcemia (p = 0.006), renal insufficiency (p = 0.035), and the efficacy of sodium supplementation (p = 0.006) were significantly associated with 30-day mortality. Binary logistic regression analysis showed that a lower albumin level (OR 0.924, 95% CI 0.861-0.991, p = 0.028) and higher ECOG score (OR 8.443, 95% CI 3.568-19.976, p < 0.001) were independent risk factors for 30-day mortality. The overall survival of emergency cancer patients with severe hyponatremia was also examined. The results of the COX regression analysis demonstrated that the efficacy of sodium supplementation (OR = 2.643, 95% CI 1.593-4.386, p < 0.001), a low albumin level (OR = 0.654, 95% CI 0.463-0.923, p = 0.016), the TNM stage (OR = 4.606, 95% CI 2.846-7.455), and a higher ECOG score (OR = 1.738, 95% CI 1.292-2.338, p < 0.001) were independent risk factors for overall survival.

Conclusions: The clinical manifestations of severe hyponatremia in emergency cancer patients are varied. Hypoalbuminemia and a higher ECOG score are independent risk factors for 30-day mortality and overall survival. Severe hyponatremia patients with a high ECOG score and/or a low albumin level should be monitored and followed more closely.