Caeruloplasmin

Some labs print 0.15 to 0.45 or 0.2 to 0.4; it is higher in pregnancy, on oestrogen-containing medicines and during any inflammation.

Caeruloplasmin is a protein made by the liver that carries most of the copper in the blood. Its level reflects how the body is handling copper. It is best known as the first test doctors use when looking into Wilson's disease, an inherited condition where copper builds up in the liver and brain. The test measures the amount of the protein in a blood sample.

Doctors request it in younger people with unexplained liver test results, movement or psychiatric symptoms, or a family history of Wilson's disease. It is also occasionally used when looking into copper deficiency.

• Any infection or inflammation, because it is an 'acute phase' protein
• Pregnancy and oestrogen-containing medicines including the combined pill
• Long-term liver disease other than Wilson's
• Some cancers and long-term inflammatory conditions

• Wilson's disease
• Copper deficiency, including after weight-loss surgery or with high zinc intake
• Severe liver disease or malnutrition
• Kidney or gut conditions where protein is lost
• Rare inherited conditions of caeruloplasmin or copper handling

• Inflammation or the pill can lift a low value into the range
• Around one in five people with Wilson's disease have a value within range, and some healthy people sit a little below range in the general population, so it is never read alone
• Different labs use different methods and ranges

No fasting needed. Usually requested with serum copper and sometimes a 24-hour urine copper, and best taken when well.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.