Endocrine Abstracts

Post-pituitary surgery hyponatraemia (HN, sodium <135 mmol/l) is relatively common and may result in prolonged hospitalisation. Herein we report a retrospective analysis of our experience in a tertiary institute. We conducted a retrospective case note review of 318 patients (M 54%, F 46%, mean age 58 years) 65.7% non-functioning adenoma (NFA), 10% somatotropinoma, 5% prolactinoma, 11% corticotropinoma (half were clinically silent), 8% craniopharyngioma, and 0.3% FSHoma, who underwent endoscopic transphenoidal surgery between 2019 and 2022. Of those 28 patients (19F, 9M) developed post-surgery HN (9% of total), of whom 54% were above 70 years of age, 61% with NFA and 18% with corticotropinoma. Of those with HN, 39% developed it within 1–3 days of surgery and 61% between 5 and 10 days. The majority had no evidence of prior hormone deficiency (61%), while 36% had pre-operative HN. The severity of HN as follows: mild (130–135 mmol/l) 7%, moderate (125–129 mmol/l) 61% and severe (<125 mmol/l)32%. The majority (68%) were on a pre-operative medication that can cause low sodium including: diuretics, ACE inhibitors, angiotensin receptor antagonists, proton pump inhibitors and antidepressants. Only 9 of 318 total patients undergoing pituitary surgery (2.9%) required readmission due to HN and that is 32% of hyponatraemia cases, most of whom had pre-operative HN or on medication that can caused it, with 54% having HN resolved within 3 days, and 32% within 5–7 days. The management of post-operative HN consisted of 43% fluid restriction (FR) alone, 32% FR and oral sodium tablets, 18% FR and medication review, 15% 1.8% sodium infusion and remaining had a combination of interventions. Our HN incidence is lower than some of the published large cohorts, mostly mild-moderate and not requiring hospital readmission. We have identified several predictive risk factors for development of post-surgery HN: pre-operative sodium, medications, advanced age and female gender, and thus proactive risk mitigation may reduce its occurrence and readmission rate.