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. Copper, Serum or Plasma Deficiency, Nutritional Menkes Syndrome Acute Copper Toxicity ICC and Chronic Copper Toxicity Wilson's Disease Smoking, Inflammatory Conditions, Pregnancy, Estrogens N = normal, ↑ = increase, ↑↑ = large increase, ↓ = decrease. Serum copper ↓ ↓ ↑, ↑↑ ↑ N or ↓ ↑, ↑↑ Serum ceruloplasmin ↓ ↓ N (early) ↑ Usually ↓; may be N in children ↑, ↑↑ Urine copper ↓ ↑ ↑ ↑ ↑, ↑↑ N CSF copper N or ↑ N Liver copper ↓ ↓ N (early) ↑, ↑↑ ↑↑ N