The analysis identified three independent predictors for delayed hyponatremia following transsphenoidal surgery for pituitary adenoma: elevated preoperative PRL levels (OR = 1.010, 95% CI: 1.003–1.018, p = 0.005), greater preoperative elevation of the diaphragma sellae (OR = 1.651, 95% CI: 1.190–2.290, p = 0.003), and the presence of hyponatremia on postoperative days 1–2 (OR = 32.65, 95% CI: 2.188–487.28, p = 0.011). This evidence concerns the gene PRL and Hyponatremia.