Would you start a vaptan or monitor an asymptomatic patient with reset osmostat and an average sodium of 126 meq/L?  

No therapy is required if the patient has hyponatremia due to a reset osmostat, since the patient will regulate the serum sodium concentration around this new baseline level. The key question is whether or not the patient actually has a reset osmostat. A patient with hyponatremia due to a reset osmo...

It might work unless their thirst threshold is also reset, in which case tolvaptan would cause only polyuria.