Diabetes Insipidus

• Nature: Excessive loss of hypotonic urine
• Treatment: Fluid resuscitation greater than urine output

Cause

Central (Failed ADH secretion)

• Idiopathic (30%)
• CNS (60%)
  • Tumour 25%
  • Pituitary surgery, Sheehan’s, panhypopituitarism (20%)
  • Head trauma (15%)
  • CNS infection
  • CVA, Aneurysm
  • Sickle cell anaemia
  • Respiratory (10%) (usually granulomatous disease)
    • Wegener’s
    • Sarcoidosis
    • TB
    • Syphilis
    • Histiocytosis

Nephrogenic (No response to ADH) (Failed concentrating ability)

• HYPOkalaemia, hypercalcaemia
• Renal disorders (myeloma, amyloidosis, ATN, TIN)
• Drugs as below

Drugs

• Alcohol
• Phenytoin
• Amphotericin
• Sulphonylureas
• Colchicine
• Gentamicin