Copper testing is primarily used to help diagnose Wilson disease, a rare inherited disorder that can lead to excess storage of copper in the liver, brain, and other organs. Less commonly, a copper test may be used to detect copper excess due to another condition, to detect a copper deficiency, or to monitor treatment for one of these conditions.
Copper is an essential mineral but in excess, it can be toxic. In the blood, most of it is incorporated into the enzyme ceruloplasmin and only a small amount is in a "free" or unbound state. (See the "What is being tested?" section for more on this.)
Typically, a total blood copper test is ordered along with a ceruloplasmin level. If the results from these tests are abnormal or unclear, then they may be followed by a 24-hour urine copper test to measure copper elimination and/or a copper test performed on a liver biopsy to evaluate copper storage in the liver.
Sometimes a free (unbound) blood copper test is also ordered. If Wilson disease is suspected, genetic testing may be performed to detect mutations in the ATP7B gene. However, these tests have limited availability and are usually performed in special reference or research laboratories.
Rarely, a copper test may be used to help diagnose Menkes kinky hair syndrome, a rare inherited disorder of copper transport dysfunction. (See Common Questions #4.)
One or more copper tests are ordered along with ceruloplasmin when someone has signs and symptoms that a health practitioner suspects may be due to Wilson disease, excess copper storage, or copper poisoning. These signs and symptoms may include:
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.
Positive but, depending on the site sampled, may be negative
High or normal
*Excess copper in the liver is often unevenly distributed and may not be detected in a sample.
Low blood copper concentrations along with increased urine copper levels, low ceruloplasmin levels, and increased hepatic copper are typically seen with Wilson 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 chronic liver disease, or that release copper from tissues, such as acute hepatitis. 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 liver is uneven and the sample is not representative of the person's condition.
If a person is being treated for Wilson disease or copper toxicity with drugs that bind copper (chelators), then that person's 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 the person's ceruloplasmin and total copper concentrations begin to rise, then the condition is likely responding to the treatment.
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 the health practitioner and/or the laboratory that will perform the test about necessary precautions. If a urine or blood copper test result is higher than expected, the health practitioner may have the test repeated with a new sample to confirm the findings.
This article was last reviewed on March 10, 2015. | This article was last modified on March 10, 2015.
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