Risk factors for disorders of sodium and water balance in the early post-operative period following pituitary surgery

Katie Mei; Ramesh Nair; Nigel Mendoza; Niamh Martin

doi:10.1530/endoabs.109.OP1.4

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Endocrine Abstracts (2025) 109 OP1.4 | DOI: 10.1530/endoabs.109.OP1.4

SFEBES2025 Poster Oral Presentations Neuroendocrinology and Pituitary (4 abstracts)

Risk factors for disorders of sodium and water balance in the early post-operative period following pituitary surgery

Katie Mei ¹ , Ramesh Nair ² , Nigel Mendoza ² & Niamh Martin ¹

Author affiliations

¹Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom; ²Department of Neurosurgery, Imperial College Healthcare NHS Trust, London, United Kingdom

Background: Arginine vasopressin deficiency (AVP-D) and hyponatremia are recognised complications of pituitary surgery and if left untreated can both increase morbidity and mortality. This study therefore aimed to investigate risk factors for the development of AVP-D and hyponatremia in patients following pituitary surgery.

Methods: A single-centre retrospective study was conducted in patients who underwent pituitary surgery between January 2016 and March 2024. Patient demographics, tumour characteristics, pre-operative and peri-operative data were collected.

Results: 264 surgery cases were analysed (132 females, 132 males). The cohort consisted of 106 functioning pituitary adenomas, 147 non-functioning pituitary adenomas, seven Rathke’s cleft cysts and four craniopharyngiomas. 36 (14%) patients developed isolated AVP-D, of which three patients developed permanent AVP-D, and 26 (10%) patients developed isolated hyponatremia. Five (2%) patients developed a biphasic response (AVP-D followed by hyponatremia), and no patients developed a triphasic response (biphasic response followed by another phase of AVP-D). Craniopharyngiomas were the only subtype associated with an increased risk of developing AVP-D (P = 0.03). Multiple logistic regression analysis showed that the independent predictors of developing hyponatremia were: pre-operative use of diuretics (OR=5.23; 95% CI=1.37-18.67; P = 0.01), lower pre-operative serum sodium (OR=0.83; 95% CI=0.71-0.96; P = 0.01) and gross total resection (OR=2.96; 95% CI=1.23-7.52; P = 0.02). The only independent predictor identified for AVP-D was cerebrospinal fluid (CSF) leak (OR=2.56; 95% CI=1.13-5.70; P = 0.02).

Conclusion: Since lower pre-operative serum sodium levels were identified as a risk factor for developing post-operative hyponatremia, individuals with pre-operative serum sodium values in the lower half of the reference range should be particularly closely monitored. Withholding diuretics peri-operatively may reduce the risk of hyponatraemia and further research is warranted to determine the optimal duration to hold diuretics peri-operatively and whether this may have any negative consequences. The association between CSF leak and AVP-D likely reflects the resection of a larger and more invasive tumour.