In a spun hematocrit, which component remains above the formed elements?

In a spun hematocrit, which component remains above the formed elements?

• A. Serum
• B. Clotting factors
• C. Plasma
• D. Water

Answer: (C)

When blood is spun in a centrifuge, its components separate by density. The red blood cells are the densest, so they settle at the bottom, with a middle layer of white blood cells and platelets. The liquid that remains on top is plasma when an anticoagulant is used, because clotting is prevented and the liquid portion of blood stays as plasma. If the sample had been allowed to clot before spinning, the top layer would be serum instead, which lacks clotting factors. So the top layer in a spun hematocrit with anticoagulated blood is plasma.

When blood is spun in a centrifuge, its components separate by density. The red blood cells are the densest, so they settle at the bottom, with a middle layer of white blood cells and platelets. The liquid that remains on top is plasma when an anticoagulant is used, because clotting is prevented and the liquid portion of blood stays as plasma. If the sample had been allowed to clot before spinning, the top layer would be serum instead, which lacks clotting factors. So the top layer in a spun hematocrit with anticoagulated blood is plasma.