CPT (Certified Phlebotomy Technician) Practice Exam

What is sodium fluoride used for?

1. Glucose

2. Cholesterol

3. Iron

4. Electrolytes

The correct answer is: Glucose

Sodium fluoride is primarily used as an additive in blood collection tubes for the preservation of glucose during transportation and storage. It functions as a glycolytic inhibitor, which means it stops the breakdown of glucose by cells, ensuring that the glucose levels in the sample remain stable until the sample can be analyzed. This is crucial because any changes in glucose levels can lead to inaccurate test results and misinterpretation of a patient's metabolic status. The other options pertain to different substances or analyses that do not require sodium fluoride for preservation or stabilization. For instance, cholesterol testing does not involve sodium fluoride specifically; it often involves different additives in the collection tubes. Iron studies are typically performed using serum samples without the need for preservatives like sodium fluoride. Electrolyte tests also do not specifically require sodium fluoride; they use other types of collection tubes and additives to ensure sample integrity. Thus, the single use of sodium fluoride aligns directly with glucose preservation in laboratory settings.