Professional and Linguistic Assessments Board (PLAB) Practice Exam

What electrolyte level is typically increased following a blood transfusion?

1. Sodium

2. Potassium

3. Calcium

4. Chloride

The correct answer is: Potassium

Following a blood transfusion, the level of potassium is typically increased. This occurs for a couple of reasons. Firstly, stored blood, particularly red blood cells, can release potassium into the plasma during the storage period, which may then be transfused into the recipient's bloodstream. The process of hemolysis, during which red blood cells break down, can also contribute to an increase in plasma potassium levels. It's important to note that this phenomenon can lead to hyperkalemia, especially in cases of massive transfusion or when the stored blood has been kept for a longer duration. Monitoring potassium levels in patients receiving transfusions is crucial given the potential complications associated with elevated potassium, such as cardiac arrhythmias. While other electrolytes like sodium, calcium, and chloride are part of the body's balance and can be influenced by various factors, they do not show the same tendency to become increased specifically as a result of blood transfusions in the same way that potassium does.