Transferrin (TF), also known as Serotransferrin or Beta-1 metal-binding globulin, is an iron-binding glycoprotein in blood plasma responsible for controlling free iron levels in biological fluids. It represents the most dynamic iron pool in the body, exhibiting high affinity for Fe(III) at physiological pH. This 679-amino acid polypeptide, primarily synthesized in the liver, comprises two globular lobes (N- and C-terminal) forming iron-binding sites. Transferrin plays a key role in iron withholding within the innate immune system, exerting a bacteriocidal effect. Its levels decrease during inflammation, and it significantly influences plutonium biochemistry in humans. Carbohydrate-deficient transferrin serves as a biomarker for heavy ethanol consumption.