POMC and Hyponatremia: Five independent risk factors were identified: tumor diameter > 25 mm (OR = 2.85, 95% CI: 1.52–5.34, P = 0.001), Knosp grade ≥ 3 (OR = 3.10, 95% CI: 1.65–5.83, P < 0.001), adrenocorticotropic hormone (ACTH)-secreting tumor (OR = 3.55, 95% CI: 1.41–8.94, P = 0.007), preoperative hyponatremia (OR = 4.20, 95% CI: 1.81–9.74, P < 0.001), and operative duration > 180 min (OR = 2.15, 95% CI: 1.13–4.08, P = 0.019).