Albumin is the most abundant protein in the blood, produced exclusively by the liver. It serves multiple essential functions — maintaining oncotic pressure (keeping fluid within blood vessels), transporting hormones, fatty acids, drugs, and minerals throughout the body, and acting as a buffer to maintain blood pH.

Because the liver produces albumin continuously, low albumin (hypoalbuminaemia) is a sensitive marker of chronic liver disease or significant liver dysfunction. It also falls in conditions causing protein loss (nephrotic syndrome, protein-losing enteropathy) or reduced dietary protein intake. Albumin is an important component of liver function tests and is also used to calculate adjusted calcium levels.