The biliary system is the major pathway of copper excretion. Biliary excretion of copper requires a copper transport protein, which is encoded by the gene ATP7B.
Variants in this gene impair the incorporation of copper into apoceruloplasmin and the excretion of copper into bile, resulting in hepatolenticular degeneration (Wilson disease), an autosomal recessive condition. Copper accumulates in the liver, causing progressive liver damage and subsequently overflows into other tissues, especially the brain. While urinary excretion of copper from this pool of free serum copper increases, it is not able to fully compensate for the decreased biliary excretion. The classical presentation is of adults with progressive neurological symptoms, low serum concentrations of caeruloplasmin, raised urinary copper excretion, and characteristic copper deposits in the corneas (Kayser-Fleischer rings). Children and adolescents frequently present with a variety of hepatic symptoms including hepatic failure. Further investigations may include a liver biopsy for quantification of copper concertation and/or testing for ATP7B variants.
Increased urinary copper can also occur in obstructive biliary disease, proteinuria, and contaminated specimens. Urine copper concentrations may also be elevated during pregnancy and in patients taking contraceptives or estrogens. Low urine copper levels may be seen in malnutrition or malabsorption.
Measuring urine copper for occupational exposure is not recommended as in normal patients it is not excreted in the urine.
Lipids/Trace Metals
UCU
Send to separating if ambient on arrival. Send to trace metals if frozen on arrival.
Aliquot to Core laboratory for UCRN. Send primary sample to trace metals.
Ambient 14 days, refrigerated (preferred) 28 days, frozen 28 days
14 days
4256