Factors affecting hormonal outcomes in patients undergoing surgery for non-functioning pituitary neuroendocrine tumors: a prospective observational study

Surgical resection of non-functioning pituitary neuroendocrine tumors (NF-PitNET) is associated with new onset hormonal axis (HA) dysfunction, and factors predicting HA dysfunction are controversial, especially in large and giant NF-PitNET. Thus, we evaluated the postoperative hormonal function and assessed factors affecting HA dysfunction in patients with NF-PitNET. This prospective observational study involved 50 patients who underwent endoscopic surgical resection of NF-PitNET in the Department of Neurosurgery (April 2023-March 2024). The preoperative tumor diameter and volume were calculated radiologically. Hormonal evaluation was performed preoperatively, and again postoperatively at 7-days and 90-days. At 90-days, 36% patients recovered HA function, 34% remained unchanged, while 30% worsened. Serum cortisol (p < 0.0001), adrenocorticotropic hormone (p = 0.012), growth hormone (p = 0.013), and luteinizing hormone (p = 0.020) levels increased significantly; serum prolactin (p = 0.016) decreased significantly; while serum thyroid-stimulating hormone, follicle-stimulating hormone, and testosterone levels remained unchanged (all p > 0.05). Overall, there was no significant change in grade of HA dysfunction (p > 0.05). Male sex (OR:5.630, 95%CI:1.648-19.232; p = 0.006), tumor volume (OR:3.511, 95%CI:1.308-9.423; p = 0.013) and tumor diameter (OR:9.489, 95%CI:2.916-30.878; p < 0.0001) were significantly associated with postoperative HA dysfunction. Tumor volume and diameter (cut-off: 8.87 cm³ and 2.95 cm, respectively) predicted postoperative HA dysfunction with a sensitivity of 96.0% and 92.0%, and a specificity of 88.0% and 76.0%, respectively. New-onset diabetes insipidus (30%) was the predominant complication. Tumor diameter and volume are significant predictors of postoperative HA dysfunction. More than one third of patients improved their HA function, while it worsened in less than a third of patients.