Effect of age and gender on plasma copper and ceruloplasmin in healthy people

Metalloenzymes are very important in humans. Controversy remains about the dietary allowance and the metabolic differences with respect to age and gender. The aim of the study was to clarify the influence of aging and gender on haematic levels of copper (Cu) and ceruloplasmin (Cer) in healthy subjects. Criteria of inclusion: healthy subjects, males (M) and females (F), of every age. Cu (70-140 mcg/dl for M, 85-155 mcg/dl for F) was measured by atomic absorption spectrophotometry and Cer (15-60 mg/dl) by nefelometry. Statistical analysis: Student's test for unpaired data, Chi-square. One hundred forty-three subjects (20-102 years, yrs) were enrolled in two groups, cut-off 65 yrs: 107 youngers (Y, 67 M, 43.8±11.7 yrs and 40 F, 40.2±10.1 yrs), and 36 elderly (E, 22 M, 70.5±5.5yrs and 14 F, 87.7±10.5 yrs) with homogeneous sex distribution (Chi-square 0.97; p=n.s.). Cu levels were higher in the E than in the Y: 117.5±17.0 mcg/dl and 102.5±19.6 (p<0.001). We found abnormal levels of Cu in 5%, homogeneously distributed in the 2 groups (Chi-square 0.08, p=ns). In the total population F had Cu levels higher than M (111.9±22.9 mcg/dl vs 103.1±17.4 mcg/dl; p=.05), while Cer levels were not significantly different (F vs M: 28.5±9.6 mg/dl vs 26.3±4.8 mg/dl; p=n.s.). Older M had Cu and ceruloplasmin higher than younger M (respectively 112.9±11.4 vs 99.7±17.9 mcg/dl, p<.01; 22.3±3.2 vs 25.3±4.9 mg/dl, p=.001). Older F had Cu levels higher than younger F (124.7±21.8 vs 107.1±21.7 mcg/dl; p<.05) while Cer values were not significantly different (24.7±2.1 vs 29.2±10.2 mg/dl, p=n.s.). In the Y, Cu levels were homogeneous in the two sexes (F vs M 107.1±21.7 vs 99.7±17.9 mcg/dl, p=n.s.), and Cer higher in F (29.2±10.2 vs 25.3±4.9 mg/dl, p<.05). In the E, Cu was higher in F (124.7±21.8 vs 112.9±11.4 mcg/dl, p<.05), and Cer higher in M (29.3±3.2 vs 24.7±2.1 mg/dl, p<.01). In the literature, an age-related increase of Cu and higher Cu levels in F have been reported. Studies in pregnant F and oral contraceptives users link the Cu difference between M and F to estrogens. Our results agree with published reports with respect to aging, but not with respect to gender. Our data on the relationship among Cu/Cer levels and gender cannot be explained by the hormone influence alone. Rather, suggest that haematic Cu and Cer levels may not be the real markers of copper status.