What is the primary use of sodium fluoride in blood collection tubes?

Sodium fluoride is primarily utilized in blood collection tubes as an enzyme inhibitor to prevent the metabolism of analytes. When blood samples are collected, the metabolism of certain substances can continue in the collection tube, potentially leading to changes in the concentrations of those analytes, especially glucose. Sodium fluoride inhibits glycolysis, the process where glucose is broken down for energy, thereby preserving the glucose level in the sample. This action ensures that the sample reflects the true concentration of glucose at the time of collection, which is crucial for accurate laboratory results.

The other options do not accurately describe the primary role of sodium fluoride in blood collection. Cooling the sample down is not a function of sodium fluoride, nor is it classified as an anticoagulant, as its main purpose is not to prevent clotting but rather to inhibit metabolic processes. Additionally, while sodium fluoride helps in the stabilization of certain analytes, such as glucose, it does not specifically stabilize cholesterol levels.