Human serum albumin is the primary protein present in human blood plasma. The main function of albumin is to maintain the oncotic pressure of blood 2. It binds to water, cations (such as Ca2+, Na+, and K+), fatty acids, hormones, bilirubin, thyroxine (T4), and pharmaceuticals (including barbiturates). Albumin represents approximately 50% of the total protein content in healthy humans 5.

Human albumin is a small globular protein (molecular weight: 66.5 kDa), consisting of a single chain of 585 amino acids organized in three repeated homolog domains (sites I, II, and III). Each domain comprises two separate sub-domains (A and B) 5.

There are various preparations of albumin that are well established and widely available in the clinical setting 9, 10, 6.

Also known as Albuminex 5% or 25%, one brand of human serum albumin is prepared from the pooled plasma of US donors in FDA-licensed facilities in the US 12. This is a biosimilar drug to existing human serum albumin and was approved for a biological license at both 5% and 25% concentrations by the FDA on June 21, 2018, 6.