Copper, Serum or Plasma

Overview:

It is used, along with serum ceruloplasmin and urine copper, to test for Wilson's disease and (more often) in monitoring the nutritional adequacy of parenteral or enteral nutrition, especially when copper deficiency may be suspected because of ongoing gastrointestinal losses of the element (see table). The test is done in suspected copper toxicity in premature infants when they are acutely ill and may not be able to assimilate the copper in their prescribed nutrition; in acute copper intoxications; or in “Indian childhood cirrhosis,” an illness not limited to Indian children.1 Serum copper is low in Menkes syndrome. Copper in the CSF is reported to mirror the neurotoxicity of copper in Wilson's disease.2 Liver copper is used to confirm Wilson's disease and Menkes syndrome and may be measured in liver disease of uncertain etiology. It can confirm ICC in the right setting. Liver copper rises with time in biliary cirrhosis, but does not confirm the diagnosis.

Serum ceruloplasmin is an acute-phase reactant type protein, and since it binds a large portion of serum copper, both serum copper and ceruloplasmin increase under the influence of inflammatory conditions and estrogen. Serum copper is, therefore, elevated in pregnancy, in patients on estrogens and estrogen-containing contraceptive drugs, in rheumatoid arthritis, and a number of other pathologic entities. It may be low with low serum proteins as in nephrosis, malabsorption, and malnutrition without necessarily reflecting inadequate liver copper stores. It is reduced under the influence of ACTH or glucocorticoids, or valproate3 therapy. Although serum copper levels are usually ordered to work up possible cases of Wilson's disease, Menkes syndrome, and ICC, serum copper alone is of only limited value. Elevations in liver tissue copper are found in Wilson's disease but may occur also in other types of liver disease, especially in primary biliary cirrhosis.4

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

The demand for sensitive noninvasive tests for Wilson's disease, especially for children in families where the disease is known to occur, has stimulated search for newer indices of copper metabolism. Urine copper after penicillamine load has recently been proposed.5

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