Caeruloplasmin is an acute phase and a transport protein. It is a blue-coloured glycoprotein (belonging to the α2-globulin electrophoretic fraction) with 8 copper atoms incorporated into the molecule during synthesis in hepatocytes. Caeruloplasmin is secreted by the liver and migrates to copper requiring tissues where it is liberated. In addition to transporting copper, it has a catalytic function in the oxidation of iron (Fe2+ to Fe3+), polyamines, catecholamines and polyphenols.
Decreased concentrations of caeruloplasmin occur during recessive autosomal hepatolenticular degeneration (Wilson's disease). This disease involves decreased synthesis because defective metallothionine prevents copper incorporation and results in copper deposits in the liver causing cirrhosis, and also in the brain, cornea and kidneys. In the rare genetic Menke’s syndrome, caeruloplasmin is low because of problems with copper absorption. Protein loss syndromes and liver cell failure also depress caeruloplasmin. As caeruloplasmin is an acute phase protein, it can be increased during acute or chronic inflammatory processes.