Trauma Nurse Core Course (TNCC) Practice Exam

If a patient has received multiple transfusions preserved with citrate, which electrolyte is most likely to drop?

1. Potassium

2. Magnesium

3. Sodium

4. Calcium

The correct answer is: Calcium

When a patient receives multiple blood transfusions preserved with citrate, calcium levels are most likely to drop because citrate is an anticoagulant that binds to calcium in the blood. This binding effect can lead to a clinical state known as citrate toxicity, which is characterized by a decrease in ionized calcium levels. The presence of citrate in the transfused blood creates a complex that prevents calcium from being available in its free, ionized form, which is essential for normal physiological functions, including muscle contraction and coagulation pathways. In cases of massive transfusion, it is common to monitor calcium levels closely, especially when large volumes of citrate-preserved blood are administered. A drop in ionized calcium can result in symptoms of hypocalcemia, such as numbness, tingling, muscle spasms, or even cardiac abnormalities. Thus, when assessing the impacts of citrate in blood transfusions, recognizing the potential for decreased calcium levels is crucial for patient management and timely intervention to prevent complications.