Pituitary apoplexy — SCE Endocrinology MCQ

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HardPituitaryPituitary apoplexySCE Endocrinology

Seven days after trans-sphenoidal surgery, a patient develops headache, nausea and confusion. Sodium is 121 mmol/L, serum osmolality is low, urine osmolality is 520 mOsm/kg and the patient appears euvolaemic. Morning cortisol is adequate. What is the most likely postoperative complication?

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Correct answer: C — Delayed SIADH after pituitary surgery

The best answer is “Delayed SIADH after pituitary surgery”. Delayed hyponatraemia around postoperative days 5–10 with inappropriately concentrated urine and clinical euvolaemia is characteristic of SIADH after pituitary surgery. “Acute cranial diabetes insipidus” is less appropriate because cranial diabetes insipidus produces dilute polyuria and often rising sodium “Primary polydipsia with maximally dilute urine” is less appropriate because primary polydipsia suppresses vasopressin and produces dilute urine “Adrenal crisis despite the adequate cortisol and euvolaemia” is less appropriate because adrenal insufficiency must be excluded but is not supported by the stated cortisol and phenotype “Osmotic diuresis from hyperglycaemia” is less appropriate because osmotic diuresis produces polyuria and does not explain concentrated urine with hypotonic hyponatraemia

Reference: Consensus statement on endoscopic endonasal pituitary surgery. https://pmc.ncbi.nlm.nih.gov/articles/PMC10668107/