Hypertonic fluids like D5% normal saline are used in critical conditions to treat hyponatremia. Which statement is true based on the notes?

• A. They are not used for hyponatremia
• B. They are used only for dehydration
• C. They are used in critical conditions to treat hyponatremia
• D. They are used to correct potassium levels

Answer: (C)

Hypertonic fluids raise the osmolality of the extracellular space, which helps when sodium is too low. In hyponatremia, brain cells can swell as water moves into them. Giving a hypertonic fluid increases plasma osmolality, drawing water out of brain cells back into the bloodstream and raising the serum sodium. In critical conditions, this rapid, controlled correction reduces cerebral edema and stabilizes the patient, which is why these fluids are used to treat hyponatremia in emergencies. They aren’t about dehydration alone, and they aren’t primarily for adjusting potassium levels; those needs are managed with other strategies. Of course, this approach requires careful monitoring to avoid correcting too quickly, which can cause separate complications.