Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Missed desmopressin plus impaired drinking is an emergency
Central diabetes insipidus, now also termed arginine vasopressin deficiency, can cause uncontrolled dilute urine and rapid hypernatraemic dehydration when desmopressin is omitted or thirst and access to water are impaired. Conversely, desmopressin with excessive fluid intake can produce dangerous hyponatraemia.
Action: Assess ABCDE, volume status, urine output, sodium, potassium and renal function urgently. Replace intravascular volume before free-water deficit, monitor sodium closely, and give parenteral desmopressin only with endocrine input and biochemical observation. Do not administer routine hypotonic fluid or repeat desmopressin blindly.
Synopsis
Diagnose and manage central arginine vasopressin deficiency while preventing life-threatening dehydration, hypernatraemia and desmopressin-associated water intoxication.
Confirm true polyuria by measured urine volume before assuming thirst or urinary frequency represents central diabetes insipidus.
Exclude osmotic diuresis, excess drinking, kidney disease, hypercalcaemia, hypokalaemia and medicines before testing the vasopressin axis.
In decompensated AVP deficiency, restore fluid first; if excessive dilute urine persists, Society for Endocrinology guidance advises desmopressin 1–2 micrograms IV or IM, with close clinical, urine-output and serum-sodium monitoring.
Investigation priorities
01
Measured 24-hour urine volumeFirst step
Confirm genuine polyuria and quantify severity before endocrine provocation.
Management branches
Stable diagnosisConfirm hypotonic polyuria
Persistent thirst and high urine output occur without acute dehydration.
Measure urine volume and review glucose, electrolytes, renal function, diuretics, lithium and deliberate high fluid intake.
Obtain paired plasma sodium or osmolality and urine osmolality under documented conditions, avoiding self-imposed dehydration.
Key medicines
DesmopressinContinue the person's verified stable formulation and dose when safe; Society guidance lists typical oral or sublingual doses of 100–200 micrograms and intranasal doses of 10–20 micrograms. In decompensated AVP deficiency, restore fluid first, then give 1–2 micrograms IV or IM if excessive dilute urine persists and reassess before repeating.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.