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Also known as: Cu; Urine Copper; Blood Copper; Free Copper; Hepatic Copper
Formal name: Copper, 24-hour urine, total and free blood, and liver (hepatic) tissue

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The Test Sample

What is being tested?

Copper is an essential mineral that the body incorporates into enzymes. These enzymes play a role in the regulation of iron metabolism, formation of connective tissue, energy production at the cellular level, the production of melanin (the pigment that produces skin color), and the function of the nervous system. This test measures the amount of copper in the blood, urine, or liver (hepatic).

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 food or liquids in the intestines, converts it to a non-toxic form 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 another protein called apoceruloplasmin to produce the enzyme ceruloplasmin. About 95% of the copper in the blood is bound to ceruloplasmin, and most of the rest is bound to other proteins such as albumin. Only a small amount is normally present in the blood in a free (unbound) state. The liver eliminates excess copper into the bile and it is removed from the body in the stool. Some copper is also eliminated in the urine.

Both excess and deficiency of copper are rare. Wilson disease, a rare inherited disorder, can lead to excess storage of copper in the liver, brain, and other organs. Copper excess (toxicity) can also occur when a person is exposed to and absorbs large amounts over a short period of time (acute exposure) or various amounts over a long period (chronic exposure).

Copper deficiency may occasionally occur in people who have conditions associated with severe malabsorption, such as cystic fibrosis and celiac disease, and in infants exclusively fed cow-milk formulas.

A rare X-linked genetic condition called Menkes kinky hair syndrome leads to copper deficiency 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 health practitioner performs a liver biopsy.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.