MON-454 Recovery of the Hypothalamic-Pituitary-Adrenal, Gonadal, and Thyroid Axes Following Trans-Sphenoidal Adenomectomy: A Single Center Experience

Background Hypopituitarism is a potential sequelea of pituitary macroadenoma or trans-sphenoidal adenomectomy (TSA). Recovery of pituitary function can occur post-TSA, and reassessment is required to avoid needless hormonal replacement. The timing and frequency of re-testing is variable across centres and the aim of this study was to determine rate of, and time to recovery of hypothalamic-pituitary adrenal (HPA), gonadal and thyroid axes postTSA. Methods We performed a single-centre retrospective analysis of TSA patients from February 2015 to September 2018. Patients with apoplexy, corticotroph adenomas, redo-surgery, emergency TSA, craniotomy or pituitary radiotherapy were excluded. Thyroid, gonadal and HPA axis adequacy was respectively assessed with TSH/freeT4, FSH/LH/estradiol or testosterone measurement and short synacthen test (SST), performed pre-TSA and at 6-weeks, 3-, 6-, and 9 to 12-months post-TSA. Results Data on 135 patients (mean age 54±17 years; 80M) were analysed. Macroadenomas occurred in 118 (87.4%), microadenoma in 8 (5.9%). Histology confirmed gonadotroph (53%), somatotroph (10.4%), plurihormonal (13.3%), lactotroph (5.2%), meningioma (1.5%), craniopharyngioma (12.6%), thyrotroph (1.5%) and metastatic malignancy (2.2%). 53.7%, 30.2% and 19.1% of patients had pre-op gonadal, thyroid and HPA function deficit respectively. 59% of patients had at least one deficit at baseline. Age was associated with the number of deficits manifested (F=6.026, p<0.001). 6-weeks post-TSA, 31.4%, 20.6% and 32% showed gonadal, thyroid and HPA axis deficit respectively. 35.7% of patients with normal pre-op pituitary function developed at least one new hormonal axis deficit at 6-weeks. Of 19.1% patients with abnormal pre-op HPA function, 30.4 % (7/23) recovered at 6-weeks. Among patients with abnormal HPA function at 6 weeks, 12.2%, 7.3% and 4.9% recovered at 3-, 6-, and 9 to 12-months respectively. 31.6% of patients with abnormal pre-op thyroid and 20% of patients with abnormal pre-op gonadal axes recovered at 6-weeks. Among patients recovering HPA axis function at 6-weeks, the majority also recovered thyroid axis (85.1% vs 14.9%, χ2=4.839, OR 2.643, p=0.03), whereas no association was found between gonadal and HPA axis recovery (54.1% vs 45.9%, p=0.16). Conclusions We demonstrate a significant rate of recovery of pre-operative pituitary deficit following TSA. 6-weeks post-operatively, gonadal failure is the most prevalent deficit. Regaining HPA axis function is a positive predictor for thyroid axis recovery but not gonadal axis recovery. HPA axis normalization can even occur at 9 to 12-months post-TSA, emphasizing the importance of periodic reassessment to avoid unnecessary hydrocortisone replacement in those who could eventually regain function. More longitudinal data are needed to assess the potential for recovery of thyroid and gonadal axes at >6 weeks post-op.