Caeruloplasmin

No special preparation is needed. A small blood sample is taken from a vein in your arm. The test takes just a few minutes. 

This test is nearly always requested alongside a copper test (measuring copper levels in your blood and sometimes your urine). Both results together give your doctor a more complete picture than either test alone. 

Caeruloplasmin is a protein made in the liver that carries about 95% of the copper found in your blood. Copper is an essential mineral that the body needs in small amounts. It is absorbed from food in the intestines and transported to the liver, where it is either stored or used to make various enzymes. The liver combines copper with a protein called apocaeruloplasmin to make caeruloplasmin, which is then released into the bloodstream. 

In Wilson’s disease, a faulty gene means the liver cannot process copper properly. Instead of being released or removed from the body, copper builds up in the liver and then spills into other organs including the brain, eyes, and kidneys. This process also results in low caeruloplasmin levels in the blood.

If your caeruloplasmin is low 

A low caeruloplasmin level is seen in up to 90% of people with Wilson’s disease. It can also be seen in copper deficiency. However, a low result does not automatically confirm Wilson’s disease — some people have low caeruloplasmin for other reasons, such as malnutrition or liver disease, without having Wilson’s disease. 

Your doctor will use your caeruloplasmin result alongside your copper levels, symptoms, and other tests to work out what the result means for you. Further tests — such as a 24-hour urine copper collection or a liver biopsy — may be needed to reach a diagnosis. 

If your caeruloplasmin is normal 

A normal result makes Wilson’s disease less likely but does not completely rule it out. A small number of people with Wilson’s disease have normal caeruloplasmin levels. If your doctor still suspects Wilson’s disease based on your symptoms or other test results, further investigation may still be recommended. 

There are also situations where a genuinely low caeruloplasmin level can appear falsely normal. These include inflammatory conditions, acute liver disease and high oestrogen levels — for example, during pregnancy or when taking the contraceptive pill or hormone replacement therapy (HRT). Your doctor will take these factors into account. 

If your caeruloplasmin is high 

Caeruloplasmin is an acute phase protein, which means its levels rise in response to inflammation, infection, or tissue damage. Raised levels can also be seen in pregnancy, with oestrogen use (including the contraceptive pill and HRT), and with certain medicines including carbamazepine, phenobarbital, and valproic acid. 

A raised caeruloplasmin level is not usually associated with Wilson’s disease, as most people with Wilson’s disease have low or normal levels. However, because these factors can mask a genuinely low level, your doctor will consider what medicines you are taking and your current health when interpreting the result. 

Reference ranges for caeruloplasmin vary between laboratories and may differ slightly by age and sex. Your lab report will include the range used for your sample. Your doctor will interpret your result in the context of your copper levels, symptoms, and medical history.

If your results suggest Wilson’s disease, your doctor will likely refer you to a specialist — usually a hepatologist (liver specialist) or neurologist, depending on your main symptoms. Further tests will help confirm the diagnosis. These may include a 24-hour urine copper collection, liver function tests, an eye examination to look for Kayser-Fleischer rings (copper deposits visible in the eyes), and sometimes a liver biopsy. 

If Wilson’s disease is confirmed, treatment is available and very effective, particularly when started early. Treatment usually involves medicines that help the body remove excess copper, or in some cases medicines that reduce the amount of copper absorbed from food. Your specialist will work with you to find the right treatment for your situation. 

If your results suggest copper deficiency, your doctor will investigate the cause and discuss appropriate treatment with you.

Several things can raise caeruloplasmin levels and make interpretation more complex: 

• pregnancy — oestrogen levels rise significantly during pregnancy and can increase caeruloplasmin 
• the contraceptive pill or HRT — oestrogen in these medicines raises caeruloplasmin levels 
• inflammation or infection — caeruloplasmin is an acute phase protein and rises with any significant inflammation in the body 
• certain medicines — including carbamazepine, phenobarbital, and valproic acid 
• some cancers — caeruloplasmin can be raised with certain types of cancer 

Because of these factors, your doctor will always interpret your caeruloplasmin result in the context of your current health, any medicines you take, and your other test results. 

Caeruloplasmin is rarely requested alone. It is almost always used alongside: 

• serum copper — measures the total amount of copper in the blood 
• 24-hour urine copper — measures how much copper the kidneys are excreting over a full day; raised in Wilson’s disease 
• liver function tests — to check for liver damage 
• liver biopsy — may be needed if Wilson’s disease is strongly suspected, to measure copper content in the liver tissue directly 
• eye examination — to look for Kayser-Fleischer rings, which are copper deposits in the outer rim of the cornea and are a hallmark sign of Wilson’s disease affecting the nervous system 

Wilson’s disease is a rare inherited condition in which the body cannot remove excess copper properly. Copper builds up in the liver, brain, and other organs and can cause serious damage if left untreated. It usually becomes apparent in childhood or early adulthood. Treatment is effective and most people with Wilson’s disease can live a normal life with the right care.