What is the major difference between serum and plasma?

What is the major difference between serum and plasma?

• A. Serum will clot
• B. Plasma has higher protein levels
• C. Electrolyte levels are higher in serum
• D. Plasma is darker in color

Answer: (B)

Plasma and serum differ mainly by the presence of clotting factors. Plasma comes from blood treated with an anticoagulant and then centrifuged, so it still contains fibrinogen and other coagulation proteins. Serum is the liquid left after the blood has clotted and been separated; the clot uses up the clotting factors, so serum lacks fibrinogen and has a lower total protein level. That’s why plasma has higher protein levels overall. The other statements aren’t the defining difference: serum does not clot (the clot forms first), electrolyte levels aren’t inherently higher in serum, and plasma isn’t reliably darker in color.

Plasma and serum differ mainly by the presence of clotting factors. Plasma comes from blood treated with an anticoagulant and then centrifuged, so it still contains fibrinogen and other coagulation proteins. Serum is the liquid left after the blood has clotted and been separated; the clot uses up the clotting factors, so serum lacks fibrinogen and has a lower total protein level. That’s why plasma has higher protein levels overall. The other statements aren’t the defining difference: serum does not clot (the clot forms first), electrolyte levels aren’t inherently higher in serum, and plasma isn’t reliably darker in color.