Endocrine Abstracts

Background: Transsphenoidal surgery (TSS) is the standard treatment for Cushing’s disease but carries the risk of postoperative complications, including adrenal insufficiency, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and arginine vasopressin (AVP) deficiency. Early identification of these complications is crucial to facilitate prompt management and reduce morbidity.

Case: A 43-year-old woman presented with acute onset vomiting, polydipsia and polyuria. She had undergone TSS for Cushing’s disease two weeks prior, requiring two operations. She had recently been reviewed by the endocrinology team and started on hydrocortisone (10 mg morning, 5 mg afternoon, 5 mg evening) for steroid withdrawal symptoms. On presentation, she had experienced two episodes of vomiting and was administered intramuscular hydrocortisone due to suspected adrenal crisis, although this was later thought to be an unlikely cause of her symptoms. Initial blood tests revealed normal sodium of 144 mmol/l (N-133-146 mmol/l), elevated serum osmolality of 307 mOsm/kg (N-275-295 mOsm/kg), and elevated urine osmolality 385 mOsm/kg. A 9 am cortisol level was 370 nmol/l (N>350 nmol/l). Despite ongoing nausea, her vomiting resolved and there were no signs of meningism. She reported drinking 3–4 litres of fluid per day and had increased urine output, raising concern for AVP deficiency in the context of recent pituitary surgery. She was commenced on intravenous fluids. Over subsequent days, her thirst improved, and fluid balance normalised, supporting a diagnosis of transient AVP deficiency. She was discharged on hydrocortisone and will be followed up in endocrine clinic. Venous thromboembolism (VTE) prophylaxis was extended for a total of three months given her high thrombotic risk post-op for Cushing’s disease.

Discussion: This case highlights the importance of vigilant postoperative monitoring in patients with Cushing’s disease undergoing TSS. Partial or transient AVP deficiency may resolve without specific treatment. Steroid cover and proactive management of fluid and electrolyte balance are warranted. Furthermore, prolonged VTE prophylaxis is critical in this high-risk group. Clinicians must maintain a high index of suspicion for these complications to ensure timely diagnosis and optimise management.