Which IV solution is hypotonic to plasma?

Which IV solution is hypotonic to plasma?

• A. 0.9% NaCl
• B. Lactated Ringer's
• C. 0.45% NaCl
• D. Hypertonic saline

Answer: (C)

Tonicity is about how the osmolality of an IV fluid compares with blood plasma. Hypotonic fluids have a lower osmolality than plasma, so water tends to move from the bloodstream into body cells, potentially causing cells to swell. Normal saline and lactated Ringer’s are designed to be roughly isotonic with plasma, meaning they largely stay in the extracellular space. Hypertonic saline, having higher solute concentration, draws water out of cells and into the bloodstream. The hypotonic option is the saline solution with a lower salt concentration than plasma (often described as half-strength saline). Because it is less concentrated than plasma, it causes water to flow into cells.

Tonicity is about how the osmolality of an IV fluid compares with blood plasma. Hypotonic fluids have a lower osmolality than plasma, so water tends to move from the bloodstream into body cells, potentially causing cells to swell.

Normal saline and lactated Ringer’s are designed to be roughly isotonic with plasma, meaning they largely stay in the extracellular space. Hypertonic saline, having higher solute concentration, draws water out of cells and into the bloodstream.

The hypotonic option is the saline solution with a lower salt concentration than plasma (often described as half-strength saline). Because it is less concentrated than plasma, it causes water to flow into cells.