NHA Phlebotomy Certification Practice Exam

How does plasma differ from serum?

1. Serum contains fibrinogen

2. Serum is obtained by centrifugation

3. Plasma contains fibrinogen

4. Plasma is obtained by centrifugation

The correct answer is: Plasma contains fibrinogen

Plasma is the liquid component of blood that contains water, electrolytes, proteins, hormones, and waste products. One of the key components of plasma is fibrinogen, which is a soluble protein that plays a crucial role in blood clotting. When blood is collected and allowed to clot, fibrinogen is converted into fibrin, which is the meshwork that forms a blood clot. As a result, serum, the liquid that remains after blood has clotted, will not contain fibrinogen. In contrast, plasma is obtained by centrifuging whole blood with an anticoagulant present, which prevents clotting from occurring. This allows for the retention of fibrinogen as well as other clotting factors. Therefore, the fundamental distinction between plasma and serum is that plasma retains fibrinogen while serum does not. Understanding this difference is important not only for laboratory procedures but also for interpreting test results and understanding the role of various blood components in health and disease. This foundational knowledge is essential for anyone working in phlebotomy or related fields.