Which statement about isotonic crystalloids is true?

Which statement about isotonic crystalloids is true?

• A. They have osmolality similar to plasma
• B. They have much higher osmolality than plasma
• C. They are always hypotonic
• D. They cannot be given intravenously

Answer: (B)

Isotonic crystalloids are solutions whose osmolality is about the same as blood plasma, so they stay mainly in the intravascular space and expand circulating volume without causing water to shift into or out of cells. Because their osmolality matches plasma, they won’t draw water out of cells (like hypertonic solutions would) or cause cells to swell (like hypotonic solutions would). That’s why the true statement is that their osmolality is similar to plasma. These fluids are routinely given IV, and common examples include normal saline and lactated Ringer’s solution.

Isotonic crystalloids are solutions whose osmolality is about the same as blood plasma, so they stay mainly in the intravascular space and expand circulating volume without causing water to shift into or out of cells. Because their osmolality matches plasma, they won’t draw water out of cells (like hypertonic solutions would) or cause cells to swell (like hypotonic solutions would). That’s why the true statement is that their osmolality is similar to plasma. These fluids are routinely given IV, and common examples include normal saline and lactated Ringer’s solution.