Ceruloplasmin is an acute phase protein and transport protein. The blue‑colored glycoprotein belongs to the α2‑globulin electrophoretic fraction and contains 8 copper atoms per molecule. Incorporation of copper into the structure occurs during the synthesis of ceruloplasmin in the hepatocytes. After secretion from the liver, ceruloplasmin migrates to copper‑requiring tissue where the copper is liberated during catabolism of the ceruloplasmin molecule. In addition to transporting copper, ceruloplasmin has a catalytic function in the oxidation of iron (Fe 2+ to Fe 3+ ), polyamines, catecholamines, and polyphenols. Decreased concentrations occur during recessive autosomal hepatolenticular degeneration (Wilson's disease). On a pathochemical level, the disease, which is accompanied by lower ceruloplasmin synthesis, occurs as a consequence of missing Cu 2+ incorporation into the molecule due to defective metallothionine. This results in pathological deposits of copper in the liver (with accompanying development of cirrhosis), brain (with neurological symptoms), cornea (Kayser‑Fleischer ring), and kidneys (hematuria, proteinuria, aminoaciduria). In homozygous carriers, ceruloplasmin levels are severely depressed. Heterozygous carriers exhibit either no decrease at all or just a mild decrease. The rare Menke's syndrome involves a genetically caused copper absorption disorder with concomitant lowering of the ceruloplasmin level. Protein loss syndromes and liver cell failures are the most important causes of acquired ceruloplasmin depressions. As ceruloplasmin is a sensitive reactant to the acute phase, increases occur during acute and chronic inflammatory processes. Great increases can lead to a green - blue coloration of the sera.