Serum albumin, the main protein of plasma, has a good binding capacity for water, Ca (2+), Na (+), K (+), fatty acids, hormones, bilirubin and drugs. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular compartments and body tissues. It also acts as a plasma carrier by non-specifically binding several hydrophobic steroid hormones and as a transport protein for hemin and fatty acids.