Functioning Pituitary Adenomas: Endocrinological Dysfunction and Postoperative Complications at a Single Institution

Educational Objective: Endoscopic pituitary surgery is the predominant modality of treatment for medically nonresponsive functioning adenomas. However, surgical management can alter pituitary gland functionality; therefore, it is important to closely monitor postoperative hormonal outcomes in this subset of patients. The primary aim of our study was to describe the endocrinological outcomes of patients with surgically treated functioning adenomas.

Methods: Retrospective analysis of all trans-sphenoidal pituitary surgeries for adenomas from 2013 to 2018 at a single tertiary referral institution was conducted. 346 patients met the inclusion criteria. Hypocortisolism, hypothyroidism, and hypogonadism were defined as central pituitary hormone deficiencies based on laboratory values measured within 6 months postoperatively requiring hormone replacement therapy. Patients on hormone therapy for diseases not related to pituitary surgery were excluded. Data were collected preoperatively and for three discrete postoperative time periods: immediate (0–1 days post-op), intermediate (4–10 days post-op), and late (1–12 months post-op).

Results: Out of 346 patients, 79 (23%) patients had functioning pituitary adenomas. Mean age at the time of resection was 44 years. Of these patients, 46% were somatotropinomas, 28% were corticotropinomas, and 27% prolactinomas, and 1% had a thyrotropinoma. Mean duration of hospital stay was 2.8 days and mean duration of follow-up was 27.1 months.

On the day of discharge, 41% (30 of 73) of patients required steroids due to low postoperative cortisol levels. Seven (10.6%) patients discharged on steroids developed hypocortisolism requiring long-term supplements. One (1.5%) patient discharged without steroids developed long-term hypocortisolism. One patient developed postoperative panhypopituitarism requiring hormone replacement therapy. Overall, 10.4% developed hypocortisolism; all patients presented in the first postoperative month. 4.5% developed hypothyroidism and 6.1% had hypogonadism postoperatively.

Eleven (14%) patients developed DI postoperatively; three required long-term desmopressin therapy. 75% of DI patients presented within the first postoperative week. Two (2.5%) patients developed SIADH; both presented during the second postoperative week. The mean sodium levels were statistically different between patients who developed DI (142 ± 3.3 vs. 140 ± 2.6, p = 0.012) and SIADH (130.5 ± 9.2 vs. 140.4 ± 3.3, p = 0.0003) as compared with those who did not during the immediate and intermediate postoperative period respectively.

During immediate postoperative period, patients with prolactinoma experienced a 70.9% decrease in their prolactin, while IGF-1 in the late postoperative period was reduced by 48% and GH by 78% (acromegaly). Cortisol reduced by 71.6% during the intermediate postoperative period (Cushing’s disease).

Conclusion: Normal preoperative cortisol levels are not a reliable indicator of risk of development of postoperative cortisol deficiency. Postoperative sodium levels during immediate post-op period are significantly associated with development of postoperative diabetes insipidus, and levels during intermediate post-op period are associated with development of postoperative SIADH.