Assessment of copper nutritional status.

Despite increased interest in the role of copper deficiency in clinical problems and an increased understanding of the physiological roles of copper, the diagnosis of a marginal deficiency has not been perfected. The use of non-standardized procedures and the effects of factors other than copper nutriture have impeded identification of the "ideal" indicator of copper nutritional status in adult humans. The specific activity of copper enzymes, or of copper-containing enzymes in blood cells, such as erythrocyte superoxide dismutase and platelet or leukocyte cytochrome c oxidase, may be a better indicator of metabolically active copper stores than the serum concentration of copper or ceruloplasmin, because the enzyme activities are sensitive to changes in copper stores and are not as sensitive to factors not related to copper nutriture. A single index, such as serum copper concentration, is inadequate for assessing the total body copper nutriture of an individual and must be supported by corroborating evidence.