Copper

Copper testing is often used to help diagnose Wilson disease. If a doctor suspects Wilson disease, then he/she would typically use a total and/or free (unbound) blood copper test alongside the caeruloplasmin concentration. 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 Wilson disease is suspected. However, these tests have limited availability and are usually performed in special reference or research laboratories.

If your healthcare professional suspects copper toxicity, copper deficiency, or a disorder that is inhibiting copper metabolism, then he/she may use blood and/or urine copper tests along with caeruloplasmin to help evaluate the patient’s condition. One or more copper tests may be requested to help monitor the effectiveness of treatment for Wilson disease, copper excess or copper deficiency.

One or more copper tests are requested along with caeruloplasmin when someone has signs and symptoms that a doctor suspects may be due to Wilson disease, excess copper storage, copper poisoning, or due to a copper deficiency. These signs and symptoms may include:

• anaemia
• nausea
• abdominal pain
• jaundice
• fatigue
• behavioural changes
• tremor
• difficulty walking and/or swallowing
• dystonia

One or more of the copper tests may be requested periodically when monitoring is recommended.

A hepatic copper test may be requested to further investigate copper storage when copper and ceruloplasmin results are abnormal or equivocal.

Copper test results must be evaluated in context and are usually assessed alongside caeruloplasmin concentration. 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 caeruloplasmin may be elevated whenever inflammation or severe infections are present. Both caeruloplasmin and copper are also increased during pregnancy and with oestrogen and oral contraceptive use.

Test results may include:

Low blood copper concentrations along with increased urine copper excretion, low caeruloplasmin concentrations, and increased hepatic copper are typically seen with Wilson disease.

Increased blood and urine copper concentrations and normal or increased caeruloplasmin concentration 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 caeruloplasmin may indicate a copper deficiency.

Normal hepatic copper may indicate that copper metabolism is functioning properly or that the distribution of copper in the patient’s liver is uneven and the sample is not representative of the person’s condition.  

If a patient is being treated for excess copper storage with chelators, then the 24-hour urine copper concentrations may be high until body copper stores decrease. Eventually, blood copper and 24-hour urine copper concentrations should normalise.

If someone is being treated for a condition related to copper deficiency and his caeruloplasmin and total copper concentrations begin to rise, then it is likely that the condition is responding to the treatment.

Medications such as oral contraceptives, carbamazepine and phenobarbital can increase blood copper concentration. 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 expected, then you may have to repeat the test to confirm the findings.

General screening for copper concentrations is not recommended or necessary. Many people with conditions not associated with copper, such as people with infections or inflammation, may have temporarily increased concentrations.