Also known as: Cu; 24-hour urine copper; total copper; non-ceruloplasmin-bound copper; free copper; hepatic copper
Name: Copper – 24-hour urine, total and free blood, and hepatic
Related tests: Ceruloplasmin
Why is the test done?
To determine the concentration of copper in the blood, urine or liver.
To help diagnose and monitor Wilson’s disease.
Sometimes to detect a deficiency or excess of the metal in the body
When is the test done?
When there is jaundice, tiredness, abdominal pain, mood changes, tremors or other symptoms that may lead your doctor to suspect Wilson’s disease or a deficiency or excess of copper in the body. Periodically, during treatment for conditions related to copper metabolism.
What samples are required?
A blood sample taken from a vein in the arm and/or a 24-hour urine sample. In special cases, a liver biopsy sample.
What is being tested?
This test measures the concentration of copper in the blood, urine or liver.
Copper is an essential mineral used by the body as a component of certain enzymes.
These enzymes are involved in regulating iron metabolism, forming connective tissue, producing energy in the cells, forming melanin, and in the functioning of the brain and nervous system.
Copper is found in many foods, including nuts, chocolate, mushrooms, shellfish, whole grains, dried fruit and liver. Drinking water and food can contain copper if the metal has been used in pipes or cookware. Normally the body absorbs copper in the intestine, makes it non-toxic by binding it to a protein and carries the complex to the liver: here some of the copper is stored and some is bound to a protein called apoceruloplasmin. By binding copper, apoceruloplasmin becomes the enzyme ceruloplasmin. About 95% of the copper in the blood is bound to ceruloplasmin. Excess copper in the liver is carried in the bile and eliminated in the stool; a smaller percentage of copper is eliminated in the urine.
Both copper deficiency and copper excess are rare. In Wilson’s disease, copper can build up to excessive levels in the liver, brain and other organs. This can cause tissue damage and symptoms such as:
- anaemia
- nausea, abdominal pain
- jaundice
- tiredness
- behavioural changes
- tremors
- difficulty walking and swallowing
- dystonia
If the kidneys are affected, urine production may decrease or stop altogether. Some of these symptoms can also be seen in copper poisoning, whether it results from acute or chronic environmental exposure to the metal or from conditions (liver disease or obstruction) that prevent or inhibit copper metabolism and excretion.
Copper deficiency may occasionally occur in patients with severe malabsorption (cystic fibrosis and coeliac disease) and in infants fed only on cow’s milk formula. Symptoms can include neutropenia, osteoporosis and microcytic anaemia.
Menkes syndrome, a rare genetic disease caused by a mutation on the X chromosome, causes copper deficiency in the brain and liver of affected children: the disease, which affects boys, causes seizures, delayed mental development, abnormal development of the arteries in the brain, and unusual sparse, brittle grey hair.
How is the sample collected?
The blood sample is obtained by inserting a needle into a vein in the arm. A 24-hour urine sample may be requested.
Sometimes a sample of liver tissue taken by biopsy is needed.
Is any special patient preparation required?
No patient preparation is required for this test.
How is the test used?
When is the test requested?
What does the test result mean?
What else should I know?
How is the test used?
Copper testing is used primarily to help diagnose Wilson’s disease. If the doctor suspects it, they should request total and/or free copper together with ceruloplasmin: if the results are abnormal or suspicious, 24-hour urine copper may be requested to measure excretion, together with an assessment of hepatic copper from a liver biopsy. In addition, genetic tests to detect mutations in the ATP7B gene can be performed, but only in specialist or research laboratories.
If the doctor suspects copper poisoning, a deficiency or a condition that inhibits copper metabolism, they may request blood and/or urine copper together with ceruloplasmin to help assess the patient’s condition. One or more tests may be requested to help monitor Wilson’s disease and copper excess or deficiency.
When is the test requested?
One or more tests, together with ceruloplasmin, are requested when the doctor thinks that signs and/or symptoms such as the following may be linked to Wilson’s disease, excess copper storage, copper deficiency or copper poisoning:
- anaemia
- nausea, abdominal pain
- jaundice
- tiredness
- behavioural changes
- tremors
- difficulty walking and swallowing
- dystonia
If monitoring copper levels is considered useful, one or more tests may be prescribed periodically.
If blood and urine test results are abnormal or suspicious, hepatic copper may be measured to study copper storage in the liver.
What does the test result mean?
Copper results must be assessed in a clinical context and, as a rule, compared with ceruloplasmin values. Concentrations outside the reference range are not enough to make a diagnosis but suggest that further investigation is needed. Interpretation can be complicated by the fact that ceruloplasmin, as an acute-phase protein, can also be raised in the presence of significant infections or inflammatory episodes.
Interpreting the results:
- Low blood copper, high urine copper, low ceruloplasmin and increased liver storage are characteristic of Wilson’s disease.
- Increased blood and urine copper with normal or high ceruloplasmin may indicate either excessive exposure to copper or a condition that reduces its excretion, such as liver disease. Increased liver storage may suggest that the condition has become chronic.
- Decreases in both blood and urine copper and in ceruloplasmin may suggest copper deficiency.
- A normal liver storage result may indicate that copper metabolism is working properly, but it may also be due to the uneven distribution of the metal in the liver: in this case the sample tested is not truly representative of the person’s condition.
If the patient is being treated with copper chelators to reduce excess copper, 24-hour urine levels may remain high until the body’s stores are reduced.
An increase in ceruloplasmin and copper levels in patients being treated for copper deficiency probably indicates a positive response to treatment.
What else should I know?
Blood copper levels may increase in patients taking medicines such as carbamazepine or phenobarbital, or in patients with rheumatoid arthritis or certain cancers; blood levels may decrease in many malabsorption conditions, such as cystic fibrosis.
Copper levels are usually low at birth and increase over the following years until they reach their peak; they then fall slightly and remain essentially stable.
Care must be taken not to contaminate samples, particularly urine, with copper from outside sources: ask your doctor or the laboratory carrying out the test for specific instructions. If blood and/or urine results are higher than expected, your doctor may ask you to repeat them for confirmation.
1. Should everyone have their copper metabolism checked?
2. Can I choose between having the copper test on blood (total and free) or on urine?
3. What happens if someone is exposed to toxic doses of copper?
4. Should I take copper supplements or try to add more copper to my diet?
1. Should everyone have their copper metabolism checked?
General screening of copper levels is neither recommended nor necessary. Many people with conditions not related to copper, such as infections or inflammation, may have temporary increases in copper levels.
2. Can I choose between having the copper test on blood (total and free) or on urine?
These tests provide complementary information. It is up to the patient and their doctor to decide which tests are needed to assess the specific situation.
3. What happens if someone is exposed to toxic doses of copper?
Copper poisoning can cause vomiting and diarrhoea and, in some cases, can damage the kidneys and liver. If you suspect you have been exposed, tell your doctor.
4. Should I take copper supplements or try to add more copper to my diet?
In most cases a normal diet meets the body’s copper needs. You should talk to your doctor before taking copper or changing your diet.