Albumin is a naturally occurring protein within the human body, playing a fundamental role in various physiological processes. Its classification often leads to questions about whether it is considered a “blood product” in the same way as whole blood. Understanding albumin’s nature and how it is prepared for medical use clarifies its distinct classification.
Understanding Albumin
Albumin is the most abundant protein found in human blood plasma, the liquid component of blood. The liver is primarily responsible for synthesizing albumin, producing approximately 10 to 15 grams daily.
This protein performs several important functions within the body. It plays a significant role in maintaining oncotic pressure, which is the osmotic pressure exerted by proteins in the blood plasma, helping to keep fluid within the blood vessels and preventing leakage into surrounding tissues. Beyond fluid regulation, albumin also acts as a transport protein, binding and carrying various substances throughout the bloodstream. These transported substances include hormones, fatty acids, bilirubin, metal ions, and many therapeutic drugs, influencing their distribution and metabolism.
Sourcing and Manufacturing of Albumin
Therapeutic albumin is exclusively derived from human plasma, which is collected from voluntary donors. The collected plasma undergoes a complex industrial process known as plasma fractionation. The most widely used method for this is the Cohn method, developed in the 1940s, which separates albumin from other plasma proteins based on differences in their solubility under varying conditions of pH, temperature, and ethanol concentration.
During this multi-step process, albumin is isolated as a highly purified fraction. To ensure the safety of the final product, extensive purification and viral inactivation steps are integrated into the manufacturing. These include methods like heat treatment, solvent/detergent treatment, and nanofiltration, which eliminate or inactivate potential viruses and other pathogens. These rigorous processes are designed to significantly reduce the risk of transmitting infectious diseases, making the manufactured albumin safe for clinical use.
Classification as a Plasma Derivative
Despite its origin from human blood plasma, the extensive processing, purification, and viral inactivation steps classify therapeutic albumin as a “plasma derivative” rather than a whole blood product. Whole blood products, like transfused blood, contain cellular components and all plasma proteins, carrying a higher risk of immune reactions or pathogen transmission. In contrast, plasma derivatives are highly purified protein fractions.
The manufacturing process removes cellular components and significantly reduces or inactivates viruses, distinguishing albumin from less processed blood components. This classification has important implications for patient safety, as the risk of transmitting infectious diseases through plasma derivatives like albumin is very low due to these robust safety measures.
Therapeutic Applications of Albumin
Albumin is used in various medical situations due to its physiological functions. It is frequently administered to expand circulating plasma volume in conditions such as shock, severe burns, or significant blood loss, where it helps restore blood pressure and fluid balance. In cases of hypoalbuminemia, a condition characterized by abnormally low albumin levels, such as those seen in severe liver disease, malnutrition, or critical illness, albumin infusions help replenish protein levels and maintain oncotic pressure.
Albumin also serves as a carrier for certain medications, aiding in their transport and distribution within the body. Its ability to bind and transport various substances makes it valuable in specific critical care settings, including some types of kidney failure or during cardiopulmonary bypass surgery.