Submitted to: International Society For Trace Elements Research In Humans
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/2002
Publication Date: N/A
Technical Abstract: Marginal copper (Cu) deficiency is difficult to study, in part because its effects may be small, but also because feeding of a deficient diet may not cause a discernable change in Cu status. The key to resolution of effects may be in the choice of Cu status index. In this study, liver Cu concentration, a commonly used index of Cu status, was compared with activity of ceruloplasmin (CP), a circulating Cu-dependent enzyme, and kidney Cu concentration for their utility in resolving effects of marginal Cu deficiency. Seventy male, weanling rats were fed diets containing, nominally, 0, 1.5, 3, 4.5 or 6 ug Cu/g of diet for 5 weeks. All three indices showed strong depression with severe deficiency (dietary Cu=0). The indices' abilities to statistically differentiate among adequate and marginal dietary Cu levels were in the order kidney Cu>liver Cu>CP. The three indices were plotted against six variables known to change with severe Cu deficiency: heart weight/body weight, hematocrit, red cell distribution width, neutrophil count, glycated hemoglobin and platelet count. Linear regression of points representing marginally-deficient rats showed that none of the variables showed significant regression with liver Cu, three showed significant regression with CP and three showed significant regression with kidney Cu. Regression coefficients with kidney Cu were always greater than those with CP. These findings indicate that kidney Cu is preferable to liver Cu as an index of Cu status in marginal deficiency and that linear regression is a possible way of testing for effects of marginal Cu deficiency, especially when effects are subtle.