A novel “total pituitary hormone index” as an indicator of postoperative pituitary function in patients undergoing resection of pituitary adenomas

The purpose of this study was to investigate the differences between pre- and postoperative pituitary hormone levels in patients undergoing surgical resection of pituitary adenoma and to identify factors associated with preoperative hypopituitarism. Data from 81 patients with histologically confirmed functioning and non-functioning pituitary adenomas (NFPA) who underwent transsphenoidal resection from January 2011 to December 2013 were retrospectively analyzed. Logistic regression was applied to analyze factors associated with preoperative hypopituitarism. In patients with functioning pituitary adenomas, GH and PRL levels declined after the operation; TSH, FSH and LH levels returned to preoperative values after an initial decline at postoperative day 1. In contrast, with the exception of a postoperative reduction in PRL level, NFPA patients had postoperative ACTH, TSH, FSH and LH levels at 4 months follow-up that were similar to preoperative levels. Similarly, a decrease in total hormone index was observed following surgery irrespective of NFPA type and in null-cell type NFPA patients with values increasing over the 4-month follow-up period. A higher percentage of patients receiving partial resection had high PRL levels (≥200 ng/ mL) compared to those receiving complete resection. Age (P = 0.041) and male sex (P = 0.004) were significantly associated with preoperative hypopituitarism. In conclusion, the postoperative total hormone index decreased immediately following surgery in all patients with pituitary adenoma who underwent resection, and then increased over the follow-up period. The extent of surgical resection correlated with PRL levels >200 ng/mL. Age and male sex were also independent risk factors for preoperative hypopituitarism.