Medical Technology Licensure Examination (MTLE) Practice Exam

Which of the following factors can cause a decrease in sodium levels during blood sampling?

1. Prolonged tourniquet application

2. Excessive fist pumping

3. Sample dilution

4. All of the above

The correct answer is: All of the above

A decrease in sodium levels during blood sampling can occur due to several factors, which highlights the importance of proper technique in sample collection. Prolonged tourniquet application can lead to hemoconcentration, which alters the concentration of electrolytes, including sodium, in the blood. The accumulation of blood components that can occur during the stasis period may artificially lower the sodium concentration in the sample. Excessive fist pumping before drawing blood can similarly impact sodium levels. When a patient pumps their fist vigorously, it can lead to the release of potassium from muscle cells and a temporary imbalance in electrolytes due to changes in blood flow and plasma volume, potentially resulting in a reduced sodium concentration. Sample dilution also plays a critical role. If the blood sample is inadvertently diluted with an anticoagulant or any other fluid, the sodium level would appear lower than it truly is, affecting the overall sodium readings. Therefore, all of these factors—prolonged tourniquet application, excessive fist pumping, and sample dilution—can contribute to a decrease in sodium levels during blood sampling. Understanding these factors is crucial for health professionals to ensure accurate laboratory results and appropriate patient management.