Both serum and plasma are components of blood. Blood comprises 55% plasma and 45% cellular components (blood cells like white and red blood cells). The yellow-colored liquid composed of 92% water is plasma, and the remaining 8% are proteins, organic salts, and compounds like amino acids, lipids, and vitamins.
The serum is obtained after clotting blood without anticoagulants, but plasma is the remaining liquid in the blood treated with anticoagulants. Likewise, the serum is a transparent fluid, the extracellular portion of blood without the fibrinogens and coagulation factors. Still, plasma is a yellow or straw-colored liquid part of the blood with both fibrinogens and coagulation factors.
The Difference Between Serum and Plasma
Although serum and plasma are the derived components of blood, they have differences in composition, color, and method of obtaining these. The differences between serum and plasma are as follows:
| Properties | Serum | Plasma |
| Definition | The serum is a component of blood obtained without using clotting factors. | Plasma is a component of blood obtained after using clotting factors. |
| How is it separated? | They centrifuge blood in plain vials. | They are centrifuging blood in vials with anticoagulants like EDTA vials (ethylenediaminetetraacetic acid). |
| Is anticoagulant required? | Anticoagulant not required. | Anticoagulant required. |
| Composition | It is composed of proteins, antibodies, antigens, and hormones. | It consists of proteins, antibodies, antigens, clotting factors like fibrinogen, etc. |
| Volume | It is very few in the amount in the blood. | 55% of blood is made up of plasma. |
| Fibrinogen | It is absent. | It is present |
| Volume of water | The serum consists of 90% water. | Plasma consists of 92-95% water. |
| Storage conditions | The storage temperature for serum is 2-8 and -20 if not analyzed immediately. The serum should not be frozen time and again because continuous freezing destroys the components of the serum. | The plasma can be stored in 2-6 and -20 or less if not analyzed immediately. Although frozen plasma can be used for years, it is not recommended to use plasma undergoing multiple freeze-thaw cycles. |
| Uses | Serums are used in different biochemistry tests in clinical laboratories. It is also used to make vaccines and anti-venoms. | Plasma samples are used to avoid in-vitro coagulation cascade activation, or special techniques were necessary to preserve or store the specimens. Plasma is also given to trauma patients to help maintain blood volume and prevent shock. |
| Separation time | Separation is longer as coagulation for 30 minutes is required before centrifugation. | It takes a shorter time as coagulation is not necessary for centrifugation. |
References
- Serum Preparation. (2022). Retrieved 10 August 2022, from https://med.uc.edu/docs/default-source/mmpc-docs/serum_plasma-preparation.pdf
- Plebani, M., Banfi, G., Bernardini, S., Bondanini, F., Conti, L., & Dorizzi, R. et al. (2019). Serum or plasma? An old question looking for new answers. Clinical Chemistry And Laboratory Medicine (CCLM), 58(2), 178-187. DOI: 10.1515/cclm-2019-0719
