Diabetes insipidus is the loss of ability to concentrate urine, and manifests as the passage of large volumes (>3L/day) of dilute urine (<300mosmol/kg) associated with thirst.
Central DI is characterised by reduced secretion of Anti Diuretic Hormone (ADH) from the posterior pituitary gland.
Nephrogenic DI is characterised by renal resistance to ADH activity in the collecting ducts.
