Assessment of liver copper status in cattle from plasma copper and plasma copper enzymes

Copper status determined by liver biopsy was also assessed by 3 plasma parameters: total plasma copper (Cu) as well as ceruloplasmin (Cp) and amine oxidase E.C.1.4.3.6. (AO) activities. While 14 out of the 98 cattle, all kept in field conditions, had liver copper levels of less than 20 mg/kg only 5 of these could be distinguished by low plasma Cu and 3 by low Cp activity. In addition, some animals with apparently adequate liver copper had relatively low plasma Cu values, ca 0.5-0.6 mg/l. None of the cattle had decreased AO activity. When all 3 plasma parameters were combined in the form [AO] divided by ([Cp] x [Cu]), detection of the low liver copper was improved in that 9 out of 14 could be distinguished, whereas animals with more than 20 mg/kg DM liver Cu could not. It is suggested that this relationship, tentatively called an index, would merit examination in other situations, since it might provide a better guide to copper status and indicate whether copper repletion therapy was worthwhile.