Serum is the liquid obtained after clotting of whole blood sample collected in a plain tube.
Some of the differences between the two are as follows:
- Plasma contains fibrinogen as well as all the other proteins, while serum does not contain fibrinogen.
- Plasma can be obtained immediately after sample collection by centrifugation, while minimum of 30 minutes are required for separation of serum from the clotted blood.
- Amount of sample is greater with plasma than with serum for a given amount of blood.
- Use of anticoagulant may alter the concentration of some constituents if they are to be measured like sodium, potassium, lithium, etc.