This test measures the amount of copper in blood. It is used to check for a deficiency or toxic level of copper in the body. This test is also used when disorders of copper metabolism, such as Wilson's disease, are suspected. Wilson’s disease is an autosomal recessive disease due to accumulation of copper in the body in toxic amounts. It presents usually at age 5–20 with unexplained liver disease, neurological or psychiatric symptoms. There is an increased excretion of urine copper, but reduced serum copper. This is because ceruloplasmin, the protein which transports copper in serum, is reduced in Wilson’s disease even though the total body load of copper, and its urinary excretion, are markedly elevated. Copper test are ordered along with ceruloplasmin when someone has signs and symptoms that may be due to Wilson disease, excess copper storage, copper poisoning, or due to a copper deficiency.