Which solution has the same number of dissolved particles as blood?

The correct answer is that all of these solutions have the same number of dissolved particles as blood, a characteristic known as isotonicity.

In the context of intravenous solutions and their relation to blood plasma, isotonic solutions maintain equilibrium, which is essential for preventing fluid shifts that could damage cells.

0.9% Normal Saline (NS) is a sterile solution containing sodium chloride, which closely matches the osmolarity of blood. It is commonly used for patient hydration and to replace lost fluids.

Dextrose 5% in Water (D5W) also has an isotonic effect when initially infused. Although it's initially isotonic, it's important to note that D5W becomes hypotonic once the dextrose is metabolized by the body. However, for the sake of this question, it is assumed to be isotonic at the beginning of infusion.

Lactated Ringer's solution contains multiple electrolytes, including sodium, potassium, calcium, and lactate, which together make it isotonic to blood, closely matching its osmolarity and electrolyte composition.

Since all the solutions provided are isotonic to blood, leading to no net movement of water into or out of cells, they share the characteristic of having a similar number