Predictors of Postoperative Hyponatremia in Patients Undergoing Head and Neck Surgery

Hyponatremia (HN) is a frequent postoperative occurrence after different surgeries, with potential impacts on recovery, hospital stay, and morbidity. Although frequently encountered, the literature regarding hyponatremia in head and neck cancer (HNC) patients remains scarce. The present study is conducted to evaluate the incidence, severity, and predictors of postoperative hyponatremia in HNC patients. A retrospective cohort study was conducted on 1058 patients who underwent head and neck surgeries between January 2019 and December 2020 at a tertiary care cancer center. Demographic, clinical, surgical, and biochemical data were analyzed from electronic medical records (EMR). Hyponatremia was classified as mild (130-135 mEq/L), moderate (125-130 mEq/L), or severe (< 125 mEq/L). Univariate and multivariate analyses were used to identify the predictors of HN. Classification and Regression Tree (CART) models were developed to form an algorithm for clinical decision making. Postoperative HN was seen in 67% of patients, with 32% classified as moderate-to-severe HN. Surgical reconstruction (OR 2.15, p < 0.001), intraoperative blood loss > 475 mL (OR 1.54, p = 0.01), fluid replacement > 1650 mL (OR 1.51, p = 0.014), and Charlson comorbidity index > 3 (OR 1.51, p = 0.016) were significant predictors of HN. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was identified in 9.3% of cases. CART analysis accurately predicted postoperative hyponatremia (69.5%) and SIADH (86%) based on perioperative variables. Hyponatremia is a frequent and potentially serious complication following head and neck cancer surgery. Surgical complexity, comorbidities, and intraoperative fluid shifts are key risk factors. Early recognition and appropriate perioperative management can help mitigate associated complications.

The online version contains supplementary material available at 10.1007/s13193-025-02437-y.