Explain the difference between serum and plasma specimens

Serum is the fluid portion of blood that has been allowed to clot. Plasma is the fluid portion of blood that has had an anticoagulant added to it. It is important to know and understand each fluid portion. Some laboratory tests require serum; others require plasma. Often the two cannot be interchanged. The differences between serum and plasma are often difficult for students to understand. Information must be reviewed often to reinforce the point.