Q: What is the cut off time limit between acute and chronic hypernatremia?
Answer: 48 hours
Acute hypernatremia can be treated in normal manner with goal to lower the serum sodium by 1 to 2 meq/L per hour and normonatremia can be achieved within 24 hours.
But by default all patients should be considered having chronic hypernatremia unless until proved otherwise. This is due to the fact that life threatening complications may occur due to rapid correction of chronic hypernatremia. Extreme care should be taken to not to make correction more than 10 meq/L in 24 hours.