polyuria, polydypsia, can't concentrate urine. Dehydrated, yet producing dilute urine.
Patients feel well until they lose access to water and then become dehydrated because the body is not responding appropriately.
There's hypernatremia with neurological symptoms such as confusion, disorientation, seizures, lethargy, coma.
ADH can be low(central) or high(nephrogenic)
Do water deprivation test
Central: Give Desmopressin
Treat underlying causes e.g Kidney disease, medications(stop Lithium)
If no improvement, try hydrochlorothiazide! or amilioride! (These diuretics will help lose some salts while patient continues to drink water)