Case history
Case history #1
A 42-year-old man undergoes transsphenoidal surgery for a large, nonfunctioning pituitary macroadenoma. Preoperatively, dynamic pituitary hormone tests were normal, as was his fluid intake and output. Two days following surgery he developed acute polyuria, extreme thirst, and polydipsia. His urine output over the next 24 hours was 6 liters, with frequent nocturia.
Case history #2
A 75-year-old woman presents to her family physician with a 6-month history of progressive fatigue and malaise with polyuria, polydipsia, and nocturia. She has a longstanding history of bipolar affective disorder, and has been receiving lithium for the past 15 years.
Other presentations
Patients with AVP deficiency or resistance due to nontraumatic etiology generally have an insidious onset of symptoms. Severe volume depletion or hypernatremia is uncommon, as increased thirst-stimulated drinking usually balances / offsets increased renal water loss. However, if free access to water is impaired (e.g., in children and older patients, and in those with cognitive or physical impairment or adipsia), then volume depletion and/or hypernatremia may be significant.
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