How should hypovolemic hypernatremia be treated?

Hypovolemic hypernatremia occurs when there is a deficit of both water and sodium, often due to conditions that lead to significant fluid loss, such as diarrhea or excessive sweating, leading to a higher concentration of sodium in the serum. The treatment aims to restore both the volume and the water balance while also addressing the elevated sodium levels.

The use of normal saline followed by half normal saline is appropriate in this context because it gradually replaces lost volume with isotonic fluid before switching to a hypotonic solution that can help correct the hypernatremia. Normal saline helps to expand intravascular volume, and half normal saline can assist in safely reducing serum sodium levels without causing rapid shifts that could lead to cerebral edema.

In contrast, other options would not be suitable for the treatment of hypovolemic hypernatremia. For example, administering 3% saline would worsen hypernatremia, while D5W could lead to the rapid dilution of sodium, potentially causing complications if not monitored carefully. Loop diuretics are not appropriate in this situation as they promote sodium loss, which could further worsen the hypernatremia and exacerbate the patient's volume status deficit.