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

Which blood samples can be affected the most by glycolysis interference?

1. Whole blood samples

2. Plasma samples

3. Serum samples

4. Capillary blood samples

The correct answer is: Serum samples

The interference of glycolysis is most significant in serum samples due to the breakdown of glucose by cells that remain in the sample after clot formation. Glycolysis, the metabolic pathway that converts glucose into pyruvate, can continue in the serum even after blood collection, leading to a decrease in glucose concentration. This is particularly important because serum is derived from the blood after clotting; thus, all cellular elements are removed, yet any residual red blood cells or platelets can still metabolize glucose. In contrast, whole blood samples may present different glucose levels primarily due to the immediate presence of cellular components that can still be metabolically active before processing. Plasma samples, which are derived from anticoagulated whole blood, experience a lesser degree of glycolysis interference before immediate separation, as anticoagulants help stop the metabolism temporarily. Capillary blood samples, while also exposed to potential glycolytic activity, usually reflect concentrations that are closely aligned with blood glucose levels without the same level of interference seen in serum. Thus, serum glucose levels are more susceptible to changes caused by glycolysis, making it the correct answer to the question.