Endocrine Abstracts

Introduction: Patients planned for first time surgery for clinically non-functioning pituitary adenoma (NFPA) were included in this prospective study.

Aims: – To study the prevalence of hypothalamic-pituitary-adrenal (HPA) axis failure preoperatively and 3 months after surgery for clinically NFPA.

– To investigate factors predicting risk of HPA axis failure postoperatively.

Hypotheses

– Endoscopic transsphenoidal surgery rescues the HPA axis in patients with NFPA.

– Postoperative pituitary failure mainly occurs after surgery for pituitary apoplexy.

Method: The study included 116 patients, (51 women, 65 men), mean age 58.6 years (range 18-93) with macroadenomas, mean largest diameter 26.9 mm, range 13-61 mm. The pathologists confirmed the diagnosis of pituitary adenoma. Fourteen patients were excluded after histopathological diagnosis other than NFPA. The surgeries were performed in a single tertiary referral centre, Oslo University Hospital, from December 2014 to October 2018. The subjects gave signed informed consent. Regional Ethics Committee approved the study. Two surgeons performed the majority of operations (102). Transsphenoidal endoscopic technique was used in 113 patients, while three were operated with open transcranial resection. The surgical indications in our series were visual disturbance (92), tumour growth and elevated/compressed optic chiasm (16), acute apoplexy (6) and headache (2).

Results: All patients were alive three months after surgery. HPA-axis failure was diagnosed with low morning cortisol in 15 patients pre-operatively. Eight of these had normal HPA axis 3 months postop confirmed by SynACTHen test. Patients with a rescued HPA function were younger; mean age 57.5 years vs. 71.0, (P=0.06). In addition, failure of HPA function three months post-operatively was found in five out of six patients undergoing acute surgery for a pituitary apoplexy, two of three patients operated trans-cranially and in two patients operated transsphenoidally for large macroadenomas (34 and 40 mm). In patients with HPA failure, the mean number of pituitary axes with failure was 2.7, compared to 0.7 axes (P<0.01) in patients with normal HPA function. Visual symptoms improved in 70 of 93 of patients with visual disturbance preoperatively. Vision was unchanged in 12 and examination of vision was missing in ten patients. Postoperatively MRI revealed a residual tumour in 62 patients.

Conclusion: Endoscopic transsphenoidal surgery rescues the HPA-axis and the visual function in most patients with clinically NFPA in our centre. Acute pituitary apoplexy, older age, open transcranial surgery and larger tumours are all risk factors for HPA-axis failure post-operatively.