Pharmacology: Albumin is a highly soluble, globular protein (molecular weight 66, 500), accounting for 70-80% of the colloid osmotic pressure of plasma. Therefore, albumin is important in regulating the osmotic pressure of plasma. Albumin 20% solution will increase the circulating plasma volume by four times the volume infused. This extra fluid reduces haemoconcentration and decreases blood viscosity. The degree and duration of volume expansion depend upon the initial blood volume. When treating patients with diminished blood volume, the effect of infused albumin may persist for many hours. The haemodilution lasts for a shorter time when albumin is administered to individuals with normal blood volume. Albumin also functions as a transport protein and binds to naturally occurring, therapeutic and toxic materials in the circulation. The binding properties of albumin may, in special circumstances, provide an indication for its clinical use.
Albumin is distributed throughout the extracellular water and more than 60% of the body albumin pool is located in the extravascular fluid compartment. The total body albumin in a 70 Kg man is approximately 320 g; it has a circulating life span of 15-20 days, with a turnover of approximately 15 g per day.