American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

Which antiglycolytic agent is preferred for testing urea nitrogen (BUN) and glucose?

1. Potassium oxalate

2. Sodium fluoride

3. Sodium iodoacetate

4. EDTA

The correct answer is: Sodium iodoacetate

The preferred antiglycolytic agent for testing urea nitrogen (BUN) and glucose is sodium fluoride. Sodium fluoride works effectively to inhibit glycolysis, the process by which glucose is metabolized. This action is critical in preserving the concentration of glucose in blood samples, ensuring accurate test results. It prevents the conversion of glucose by red blood cells, which can lead to falsely low glucose levels if samples are not processed quickly. Moreover, sodium fluoride also stabilizes urea nitrogen levels in serum, making it useful for BUN testing as well. This dual action makes sodium fluoride a suitable choice when both glucose and urea nitrogen tests need to be performed from the same sample. While potassium oxalate is another antiglycolytic agent, it primarily serves as an anticoagulant and is not as effective in preserving glucose levels as sodium fluoride. Similarly, sodium iodoacetate is less commonly used for these tests, despite its antiglycolytic properties. EDTA is primarily used for hematological tests and does not serve the same purpose in preserving urea nitrogen and glucose. Thus, sodium fluoride is the preferred agent for maintaining the integrity of samples for both BUN and glucose testing.