Abstract
PurposeThe syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a well-known complication of transsphenoidal pituitary surgery, related to inappropriate secretion of arginine vasopressin (AVP). Its diagnosis is based on hyponatremia, with a peak of occurrence around day 7 after surgery and, to date, no early marker has been reported. In particular, copeptin levels are not predictive of hyponatremia in this case. Oxytocin (OXT) is secreted into the peripheral blood by axon terminals adjacent to those of AVP neurons in the posterior pituitary. Besides its role in childbirth and lactation, recent evidences suggested a role for OXT in sodium balance. The contribution of this hormone in the dysnatremias observed after pituitary surgery has however never been investigated.MethodsWe analyzed the urinary output of OXT in patients subjected to transsphenoidal pituitary surgery.ResultsWhile OXT excretion remained stable in patients who presented a normonatremic postoperative course, patients who were later diagnosed with SIADH-related hyponatremia presented with a significantly increased urinary secretion of OXT 4 days after surgery.ConclusionTaken together, these results show for the first time that urinary OXT output remains normally stable after transsphenoidal pituitary surgery. OXT excretion however becomes abnormally high on or around 4 days after surgery in patients later developing hyponatremia, suggesting that this abnormal dynamics of OXT secretion might serve as an early marker for transsphenoidal surgery-related hyponatremia attributed to SIADH.
Highlights
Transsphenoidal surgery of the pituitary gland is a wellestablished treatment for pituitary gland tumors
Seven were diagnosed with secretion of antidiuretic hormone (SIADH) during hospitalization. They were treated in accordance with intra-hospital guidelines until normalization of sodium levels as well as urinary output and patients were discharged without further complication
They were not significantly different for age, gender, ethnicity, baseline weight, baseline arterial blood pressure (BP), comorbidities, pathology or treatments. Both groups showed no statistical difference in the occurrence of transient diabetes insipidus (DI), basal cortisol values, hypocortisolemia necessitating maintained corticoid replacement therapy or average daily urinary output volume from D0 until day 7 (D7) (Table 1)
Summary
Transsphenoidal surgery of the pituitary gland is a wellestablished treatment for pituitary gland tumors. While the different technical aspects of this surgery are well documented, it is not deprived of risks and complications such as hyponatremia, which might occur in up to more than a third of the patients as was reported in the literature [1,2,3,4,5,6]. AVP is produced in the hypothalamus and secreted through nervous terminals running to the posterior part of the pituitary gland. Oxytocin (OXT), another hormone, is secreted in the bloodstream through nervous terminals adjacent to the ones of AVP in the posterior hypophysis [8].
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