Massachusetts Pharmacy Technician License Practice Test

In normal saline (NS), what percentage of sodium chloride (NaCl) does it contain?

1. 0.9%

2. 0.45%

3. 1.0%

4. 2.0%

The correct answer is: 0.9%

Normal saline (NS) is an isotonic solution commonly used in medical settings for fluid replacement and hydration. It contains a specific concentration of sodium chloride (NaCl), which is 0.9%. This percentage is critical as it closely matches the salt concentration in the human body, such as in blood plasma, making it safe for intravenous use without causing cellular osmotic imbalances. The 0.9% concentration ensures that the solution is neither hypotonic nor hypertonic, helping to maintain proper fluid and electrolyte balance when administered to patients. The other percentages listed are lower or higher concentrations of sodium chloride, which would alter the osmotic balance and could potentially lead to complications if used inappropriately. For instance, a 0.45% solution is hypotonic and might be used for different clinical purposes, while a 1.0% or 2.0% solution is hypertonic and can draw water out of cells, risking dehydration of the cells if not monitored closely. Thus, the correct answer emphasizes the significance of using the precise percentage of sodium chloride that aligns with bodily fluids for effective and safe medical treatment.