**Question:** Which of the following is hypertonic?

A. Sodium chloride (NaCl) solution with a higher concentration of sodium ions than in the surrounding tissue
B. Sodium chloride (NaCl) solution with a higher concentration of chloride ions than in the surrounding tissue
C. Dextrose (glucose) solution with a higher concentration of glucose than in the surrounding tissue
D. Dextrose (glucose) solution with a higher concentration of water than in the surrounding tissue

**Correct Answer:** D. Dextrose (glucose) solution with a higher concentration of water than in the surrounding tissue

**Core Concept:** Hypertonic solutions contain solutes at higher concentrations than in the surrounding tissue or body fluids, leading to osmotic imbalance and cell shrinkage.

**Why the Correct Answer is Right:** A hypertonic solution is one that has a higher concentration of solutes compared to the surrounding tissue or body fluids, causing osmotic imbalance and subsequent cell shrinkage.

In this case, option D (dextrose solution with a higher concentration of water) is the correct answer because it addresses the solute aspect of hypertonicity. Dextrose is a sugar molecule that contributes to the overall solute concentration in the solution. When dextrose solution is placed in contact with a tissue or body fluid, the water will move from the relatively hypertonic dextrose solution into the tissue or fluid through osmosis, leading to cell shrinkage and potential tissue damage.

**Why Each Wrong Option is Incorrect:**

A. NaCl (sodium chloride) hypertonicity depends on the sodium ion concentration, not the chloride ion concentration. The osmotic effect is determined by the solute concentration, not the type of solute.

B. Hypertonicity due to chloride ions would be measured by the chloride ion concentration, not the chloride ion type. The osmotic effect is based on solute concentration, not the type of solute.

C. Hypertonicity is determined by glucose concentration, not glucose type. It's essential to focus on solute concentration for assessing hypertonicity.

**Clinical Pearl:**

Understanding the concept of hypertonicity is crucial in preventing complications related to fluid replacement therapies, such as administering hypertonic solutions (e.g., normal saline) into the body without considering the solute concentrations can lead to cellular dehydration, oedema, and eventually tissue damage. It is essential to consider the solute concentrations when assessing the osmotic properties of a solution.