Predictive Factors and Scoring System for Delayed Symptomatic Hyponatremia Following Endoscopic Endonasal Surgery: A Single-Center Retrospective Study.

Background: Delayed symptomatic hyponatremia (DSH) is one of the common complications following endoscopic endonasal surgery (EES). Currently, published studies have predominantly focused on delayed postoperative hyponatremia, while there is relatively limited research on DSH.

Methods: We analyzed 175 consecutive cases from a single center between 2019 and 2023, involving patients who underwent EES for pituitary adenoma or Rathke's cleft cyst, all histopathologically confirmed. We collected preoperative, intraoperative, and postoperative data, and performed statistical analysis to determine the incidence of postoperative diabetes insipidus (DI) and identify significant predictive factors. Based on these factors, we developed a simplified scoring system.

Results: There were 29 cases (16.6%) of DSH occurrence. In the binary logistic regression analysis, Knosp grade ≥3 (odds ratio [OR], 4.19; 95% confidence interval [CI], 1.26-13.92; P = 0.019), intraoperative cerebrospinal fluid leaks (OR, 3.93; 95% CI, 1.49-10.34; P = 0.006), serum sodium on the second day after surgery (OR, 0.88; 95% CI, 0.78-1.00; P = 0.049), and postoperative DI (OR, 2.88; 95% CI, 1.10-7.53; P = 0.031) were factors with an independent predictive value for DSH. The scoring system achieved a maximum area under the receiver operating characteristic curve of 0.789 (95% CI, 0.697-0.881), with a cutoff value of 1, sensitivity of 86.2%, and specificity of 59.6%.

Conclusions: The incidence rate of DSH after EES in patients was 16.8%. Knosp grade ≥3, intraoperative cerebrospinal fluid leaks, serum sodium concentration on the second day after surgery, and postoperative DI were associated with the occurrence of DSH.