Hypernatremia + voluminous dilute urine (osm ~80)
Calculators: csna
Confirm: water deprivation → responds to desmopressin (central) not nephrogenic
Treat: Desmopressin (DDAVP) IV/intranasal/PO
Nephrogenic → thiazide, amiloride, low-salt, stop lithium
Order set Serum + urine osmolality, Na Water deprivation + desmopressin test Pituitary MRI Criteria Admit Severe hypernatraemia/dehydration
ICU ↓GCS / haemodynamic instability
Discharge Desmopressin established, Na normalising, MRI follow-up
Clinical detail — differentials, red flags, pitfalls, disposition Red flags Severe hypernatraemia ↓GCS Differentials Nephrogenic DI Primary polydipsia Osmotic diuresis Common mistakes Confusing central vs nephrogenic Over-rapid Na correction Disposition & follow-up Desmopressin; treat underlying pituitary cause.
Discharge package Medications Desmopressin
Follow-up Endocrine; sodium monitoring
Warning symptoms Excessive thirst/urination, confusion
💊 Treatment detail — doses & preparation Desmopressin (DDAVP) ADH analogue
Dose VWD: 0.3 mcg/kg IV/SC (max 20 mcg) or 300 mcg intranasal. DI: 100–200 mcg PO BD–TDS or 10–20 mcg intranasal
Preparation IV: dilute in 50 mL NS over 15–30 min; tablets/lyophilisate/nasal spray
Monitor Na⁺ (hyponatraemia/seizures — restrict fluids after dose), VWF:Ag response
Free water replacement supportive
Dose Oral water preferred; IV 5% dextrose matched to urine losses if severe
Preparation —
Monitor Na⁺ q4–6 h during correction (max 8–10/24 h)
📖 Endocrine Society / expert consensus Reviewed July 2026