129 Ceruloplasmin (CP)
Ceruloplasmin is a copper-containing protein made in the liver; it carries most of the copper in the blood (about 65–90%). It is also an enzyme (a ferroxidase) that converts iron to its ferric form so that it can bind to transferrin, linking copper and iron metabolism. The liver incorporates copper into ceruloplasmin and excretes excess copper into the bile. Ceruloplasmin is also an acute-phase protein, rising in inflammation and pregnancy. Its main clinical use is in the diagnosis of Wilson disease, an inherited disorder of copper excretion.
Wilson disease
In Wilson disease, mutations in the ATP7B gene prevent the liver from incorporating copper into ceruloplasmin and excreting it into bile. Copper accumulates in the liver, brain and eyes. It presents with liver disease (from raised enzymes to acute liver failure), neurological symptoms (tremor, dystonia, speech and swallowing problems) or psychiatric changes, mostly between 5 and 35 years of age. Diagnosis combines low ceruloplasmin, high 24-hour urinary copper, Kayser–Fleischer rings in the cornea, liver copper content and genetic testing; it is treatable with chelators or zinc.
Other causes of abnormal values
Low ceruloplasmin
Wilson disease (and some carriers), severe liver failure, protein loss (nephrotic syndrome, enteropathy), malnutrition, copper deficiency (after bariatric surgery, excess zinc), Menkes disease, aceruloplasminaemia.
High ceruloplasmin
Inflammation and infection, pregnancy, oestrogens and oral contraceptives, some cancers, biliary obstruction. These can mask low values in Wilson disease.
Unexplained liver disease in a young person, especially with tremor, clumsiness, speech changes or behavioural change, should prompt testing for Wilson disease.
References
This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.
Published on 12 May 2024