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Test Catalog

Test ID: CUS    
Copper, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of:

-Wilson disease

-Primary biliary cirrhosis

-Primary sclerosing cholangitis

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Copper (Cu) is an important trace element that is associated with a number of metalloproteins. Cu in biological material is complexed with proteins, peptides, and other organic ligands. Up to 90% of Cu exported from the liver into peripheral blood is in the protein bound form either to ceruloplasmin, transcuprein, or metallothionein. A smaller amount of Cu in plasma (<10%) is bound to albumin by specific peptide sequences, and this Cu is in equilibrium with plasma amino acids. The ceruloplasmin molecule contains 6 to 8 atoms of Cu per molecule with 6 atoms of Cu involved in the protein's ferroxidase and free radical scavenging activities. The other 1 to 2 atoms of Cu are termed "labile" and may allow ceruloplasmin to act as a Cu transporter, with a pool of Cu being exchanged between albumin, transcuprein, and the labile sites of ceruloplasmin.

 

Low serum copper, most often due to excess iron or zinc ingestion and infrequently due to dietary copper deficit, results in severe derangement in growth and impaired erythropoiesis. Low serum copper is also observed in hepatolenticular degeneration (Wilson disease) due to a decrease in the synthesis of ceruloplasmin and allelic variances in cellular metal ion transporters. In Wilson disease, the albumin-bound copper may actually be increased, but ceruloplasmin copper is low, resulting in low serum copper. However, during the acute phase of Wilson disease (fulminant hepatic failure), ceruloplasmin and copper may be normal; in this circumstance, hepatic inflammation causes increased release of ceruloplasmin. It is useful to relate the degree of liver inflammation to the ceruloplasmin and copper-see discussion on hypercupremia below. Significant hepatic inflammation with normal ceruloplasmin and copper suggest acute Wilson disease.

 

Other disorders associated with decreased serum copper concentrations include malnutrition, hypoproteinemia, malabsorption, nephrotic syndrome, Menkes disease, copper toxicity, and megadosing of zinc-containing vitamins (zinc interferes with normal copper absorption from the gastrointestinal tract).

 

Hypercupremia is found in primary biliary cirrhosis, primary sclerosing cholangitis, hemochromatosis, malignant diseases (including leukemia), thyrotoxicosis, and various infections. Serum copper concentrations are also elevated in patients taking contraceptives or estrogens and during pregnancy.

 

Since the gastrointestinal (GI) tract effectively excludes excess copper, it is the GI tract that is most affected by copper ingestion. Increased serum concentration does not, by itself, indicate copper toxicity.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

0-2 months: 0.40-1.40 mcg/mL

3-6 months: 0.40-1.60 mcg/mL

7-9 months: 0.40-1.70 mcg/mL

10-12 months: 0.80-1.70 mcg/mL

13 months-10 years: 0.80-1.80 mcg/mL

> or =11 years: 0.75-1.45 mcg/mL

Interpretation Provides information to assist in interpretation of the test results

Serum copper below the normal range is associated with Wilson disease, as well as a variety of other clinical situations (see Clinical Information). Excess use of denture cream containing zinc can cause hypocupremia.

 

Serum concentrations above the normal range are seen in primary biliary cirrhosis and primary sclerosing cholangitis, as well as a variety of other clinical situations (see Clinical Information).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. McCullough AJ, Fleming CR, Thistle JL, et al: Diagnosis of Wilson's disease presenting as fulminant hepatic failure. Gastroenterology. 1983;84:161-167

2. Wiesner RH, LaRusso NF, Ludwig J, Dickson ER: Comparison of the clinicopathologic features of primary sclerosing cholangitis and primary biliary cirrhosis. Gastroenterology. 1985;88:108-114

3. Spain RI, Leist TP, De Sousa EA: When metals compete: a case of copper-deficiency myeloneuropathy and anemia. Nat Clin Pract Neurol. 2009 Feb;5(2):106-111

4. Kale SG, Holmes CS, Goldstein DS, et al: Neonatal Diagnosis and Treatment of Menkes Disease. N Engl J Med. 2008 Feb 7;358(6):605-614

5. Nations SP, Boyer PJ, Love LA, et al: Denture cream: An unusual source of excess zinc, leading to hypocupremia and neurologic disease. Neurology. 2008;71;639-643

6. Rifai N, Horwath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018

Special Instructions Library of PDFs including pertinent information and forms related to the test