E23.2
DESCRIPTION
Damage to the posterior pituitary leading to deficient production of antidiuretic hormone. Characterised by the passage of large amounts of dilute urine, usually >2.5 litres daily.
Causes include head trauma and neurosurgery but most cases are idiopathic.
Consultation with a specialist is recommended.
GENERAL MEASURES
Rehydration with water or hypotonic fluids.
MEDICINE TREATMENT
Postoperative or acutely ill patients:
- Desmopressin, IV/SC, 2–4 mcg daily, either as a single dose or in 2 divided doses.
OR
- Desmopressin, nasal spray, 10–40 mcg daily, either as a single dose or in 2–3 divided doses.
OR
- Desmopressin, oral, 0.05 mg, 8–12 hourly.
- Optimal dose: 0.1–0.8 mg daily.
- Adjust dose according to response to a maximum of 1.2 mg daily in divided doses.
If patient has a normal thirst mechanism, and does not receive IV fluids for other purposes:
- oral, intranasal, or IV/SC dosing can be used; and
- keep urine osmolality at 450–600 mOsm/kg.
If patient requires IV fluids and/or is unable to regulate total fluid intake by thirst mechanism:
- IV dosing is preferred; and
- continually adjust the level of antidiuresis to maintain hydration and plasma sodium within the normal.
Replacement therapy:
- Desmopressin, nasal spray, 10–40 mcg daily, either as a single dose or in 2–3 divided doses.
- Adjust morning and evening doses separately for appropriate diurnal rhythm of water turnover.
OR
- Desmopressin, oral, 0.05 mg, either as a single dose or in 2–3 divided doses.
- Optimal dose: 0.1–0.8 mg daily.
- Adjust dose according to response to a maximum of 1.2 mg daily in divided doses.
REFERRAL
All patients diagnosed or suspected.
Water deprivation may be necessary to confirm the diagnosis. Careful monitoring of electrolytes and exclusion of fluid overload while on therapy is essential to determine the appropriate dose.