Copper is found in many foods including nuts, chocolate, mushrooms, shellfish, whole grains, dried fruits, and liver. Drinking water may acquire copper as it flows through copper pipes, and food may acquire it when people cook or serve food in copper dishes. Normally, the body absorbs copper from the intestines, makes it nontoxic by binding it to a protein, and transports it to the liver. The liver stores some of the copper and binds most of the rest to a protein called apoceruloplasmin that, when copper is attached, becomes the enzyme ceruloplasmin. About 95% of the copper in the blood is bound to ceruloplasmin. The liver excretes excess copper into the bile and it is removed from the body in the stool. Some copper is also excreted in the urine.
Both excesses and deficiencies of copper are rare. Wilsons disease, an inherited disorder, can lead to excess storage of copper in the liver, brain, and other organs. This can cause tissue damage and signs and symptoms such as:
If the kidneys are involved, then urine production may be decreased or absent. Some of these symptoms may also be seen with copper poisoning that is due to acute or chronic environmental exposure to copper or due to conditions such as liver disease or obstructions that prevent or inhibit copper metabolism and excretion.
Copper deficiencies may occasionally occur in patients who have conditions associated with severe malabsorption, such as cystic fibrosis and celiac disease, and in infants exclusively fed cow-milk formulas. Symptoms may include neutropenia, osteoporosis, and microcytic anemia. A rare X-linked genetic condition called Menkes kinky hair syndrome leads to copper deficiencies in the brain and liver of affected infants. The disease, which affects primarily males, is associated with seizures, delayed development, abnormal artery development in the brain, and unusual gray brittle kinky hair.
How is the sample collected for testing?A blood sample is obtained by inserting a needle into a vein in the arm and/or a 24-hour urine sample is collected. Sometimes a doctor performs a liver biopsy.
Is any test preparation needed to ensure the quality of the sample?No test preparation is needed.
How is it used?Copper testing is primarily ordered to help diagnose Wilsons disease. If a doctor suspects Wilsons, then he would typically order a total and/or free (unbound) blood copper test along with a ceruloplasmin level. If these tests are abnormal or equivocal, then they may be followed by a 24-hour urine copper test to measure copper excretion and a hepatic (liver) copper test to evaluate copper storage. Genetic testing may also be performed to detect mutations in the ATP7B gene if Wilsons disease is suspected. However, these tests have limited availability and are usually performed in special reference or research laboratories.
If a doctor suspects copper toxicity, copper deficiency, or a disorder that is inhibiting copper metabolism, then he may order blood and/or urine copper tests along with ceruloplasmin to help evaluate the patients condition. One or more copper tests may be ordered to help monitor the effectiveness of treatment for Wilsons disease, copper excess, or copper deficiency.
When is it ordered?One or more copper tests are ordered along with ceruloplasmin when someone has signs and symptoms that a doctor suspects may be due to Wilsons disease, excess copper storage, copper poisoning, or due to a copper deficiency. These signs and symptoms may include:
- nausea, abdominal pain
- behavioral changes
- difficulty walking and/or swallowing
One or more of the copper tests may be ordered periodically when monitoring is recommended.
A hepatic copper test may be ordered to further investigate copper storage when copper and ceruloplasmin results are abnormal or equivocal.
What does the test result mean?Copper test results must be evaluated in context and are usually compared to ceruloplasmin levels. Abnormal copper results are not diagnostic of a specific condition; they indicate the need for further investigation. Interpretation can be complicated by the fact that ceruloplasmin is an acute phase reactant it may be elevated whenever inflammation or severe infections are present. Both ceruloplasmin and copper are also increased during pregnancy and with estrogen and oral contraceptive use.
Test results may include:
- Low blood copper concentrations along with increased urine copper levels, low ceruloplasmin levels, and increased hepatic copper are typically seen with Wilsons disease.
- Increased blood and urine copper concentrations and normal or increased ceruloplasmin levels may indicate exposure to excess copper or may be associated with conditions that decrease copper excretion such as liver disease. Increased hepatic copper may be present with chronic conditions.
- Decreased blood and urine copper concentrations and decreased ceruloplasmin may indicate a copper deficiency.
- A normal hepatic copper test may indicate that copper metabolism is functioning properly or that the distribution of copper in the patients liver is uneven and the sample is not representative of the persons condition.
If a patient is being treated for excess copper storage with chelators, then his 24-hour urine copper levels may be high until body copper stores decrease. Eventually, blood copper and 24-hour urine copper concentrations should normalize.
If someone is being treated for a condition related to copper deficiency and his ceruloplasmin and total copper concentrations begin to rise, then the condition is likely responding to the treatment.
Is there anything else I should know?Medications such as carbamazepine and phenobarbital can increase blood copper levels. They may also be elevated with rheumatoid arthritis and with some cancers, and decreased with a variety of conditions associated with malabsorption, such as cystic fibrosis.
Total serum copper concentrations are normally low at birth, rise over the next few years, peak, and then decline slightly to a relatively stable level.
Care must be taken, especially with a 24-hour urine sample, not to contaminate the sample with an external source of copper. Talk to your doctor and/or the laboratory that will perform your test about necessary precautions. If a urine or blood copper test result is higher than the doctor expects, then he may have you repeat the test to confirm the findings.
Should everyones copper metabolism be evaluated?
Can I choose either a blood (total or free) or urine copper test?
What happens if I am exposed to toxic amounts of copper?
Should I be taking copper supplements or trying to get more copper in my diet?