Assessment of copper status in pregnancy by means of determining the specific oxidase activity of ceruloplasmin

Background: Conditions not directly related to copper nutriture, such as pr egnancy, infections and inflammation, which increase serum copper concentra tion even during copper deprivation, may be expected to conceal changes in copper status. It has been suggested that the specific enzymatic activity o f ceruloplasmin (activity per unit mass of enzyme protein) may be a sensiti ve indicator of copper status and is not affected by factors such as hormon es or sex. In this study, we investigated the behaviour of specific oxidase activity of ceruloplasmin and the copper/ceruloplasmin ratio in pregnant w omen. Methods: Copper, immunoreactive ceruloplasmin and its oxidase activit y were determined in serum from 52 women in the last trimester of normal pr egnancy, and in 50 control women of similar age living in the same area and who were not taking oral contraceptives. The results are expressed as mean +/- S.E.M. Results: In the group of pregnant women, significantly higher s erum levels of copper, ceruloplasmin and its oxidase activity were found th an in the control group (p < 0.001). In both groups, a high correlation was found between these biochemical variables (r <greater than or equal to> 0. 905, p < 0.001). However, in the group of pregnant women the specific oxida se activity for ceruloplasmin (364.4 +/- 33 vs. 407.5 +/- 3.8 U/g) and the copper/ceruloplasmin ratio (2.82 +/- 0.03 vs. 3.19 +/- 0.04 <mu>g/mg) were significantly lower than in the control group ( p < 0.001). Conclusions: Al though pregnancy accelerates the rate of ceruloplasmin protein synthesis an d release with an increase of serum copper, the decrease in specific oxidas e activity of circulating ceruloplasmin would be an indicator of the degree of depiction of the mother's copper deposits in order to deal with the foe tus' needs. (C) 2001 Elsevier Science B.V. All rights reserved.