Which factor is a common cause of increased blood osmolality that can drive fluid shifts toward the bloodstream?

Which factor is a common cause of increased blood osmolality that can drive fluid shifts toward the bloodstream?

• A. Adequate hydration
• B. Vomiting
• C. Overhydration
• D. Regular meals

Answer: (B)

When blood osmolality increases, water moves from the intracellular and interstitial spaces into the bloodstream to dilute the plasma. Vomiting removes water more than solutes, so plasma osmolality rises. That higher osmolality draws water out of cells into the blood, shifting fluid toward the circulation. Adequate hydration lowers osmolality, overhydration lowers it, and regular meals don’t notably raise plasma osmolality.

When blood osmolality increases, water moves from the intracellular and interstitial spaces into the bloodstream to dilute the plasma. Vomiting removes water more than solutes, so plasma osmolality rises. That higher osmolality draws water out of cells into the blood, shifting fluid toward the circulation. Adequate hydration lowers osmolality, overhydration lowers it, and regular meals don’t notably raise plasma osmolality.