Impact of surgical factors on delayed hyponatremia in patients with nonfunctioning pituitary adenoma after endonasal endoscopic transsphenoidal procedure

PURPOSE: Delayed hyponatremia can occur after pituitary surgery, resulting in prolonged hospitalization. However, the influence of surgical factors after such a procedure has not been well established. The impact of surgery and related factors on delayed hyponatremia was investigated. METHODS: This was a retrospective analysis of 137 consecutive patients who underwent transsphenoidal surgery for a nonfunctioning pituitary adenoma between 2008 and 2019. Preoperative (demographics, comorbidities), intraoperative (resection extent, operation time, blood loss volume, cerebrospinal fluid leak, tumor consistency), and postoperative [hematoma, meningitis, diabetes insipidus (DI), hormonal assessment] data were collected, with statistical analysis of each factor performed. RESULTS: Among the 137 patients, delayed hyponatremia occurred in 31 (22.6%). Multivariate analysis revealed that those with hypertension had a significantly higher likelihood of avoiding delayed hyponatremia (p = 0.004). Although no correlations of direct surgical factors with delayed hyponatremia were found, multivariate analysis of indirect surgical factors showed that presence of a firm tumor, transient DI, and meningitis were significantly associated with delayed hyponatremia (p = 0.014, 0.001, and 0.047, respectively). There was also a significant association of severe hyponatremia with appearance of symptoms (p = 0.002). CONCLUSION: There was a tendency for hypertension to be associated with delayed hyponatremia avoidance, with indirect surgical factors including tumor consistency, transient DI, and meningitis found to have an influence on delayed hyponatremia. It was concluded that attention should be given to non-hypertensive patients with a firm tumor, transient DI, or meningitis after pituitary surgery, as delayed hyponatremia may occur.