Serum copper and zinc concentration in premature and small-for-date infants

Abstract

Serum copper (Cu) and zinc (Zn) concentrations were measured in neonates with an appropriate birth weight for gestational age (AGA) and in small-for-gestational age infants. At 7 days of age, there was a positive correlation between serum Cu concentration and gestational age (GA) (r = 0.63; P <0.001) and a negative correlation between Zn concentration and GA (r = 0.62; P <0.01). At 7 days of age, the mean (±S.E.) concentrations in AGA full-term infants (Cu, 79 ± 8 μg/dl; Zn, 84 ± 4) were similar to those in small-for-gestational age, full term infants (Cu, 78 ± 6 μg/dl; Zn, 85 ± 12). In preterm infants, there was also no difference between AGA and small-for-gestational age infants. In 23 AGA infants with a birth weight of less than 1500 g, serum Cu concentration increased from 51 ± 7 μg/dl at the age of 7 days to 86 ± 7 μg/dl at the age of 60 days (paired t-test: P < 0.05) whereas serum Zn concentration decreased from 149 ± 9 to 91 ± 5 μg/dl (P <0.01). A positive correlation was found between serum Zn concentration and daily intake of Zn (n = 39; r = 0.3458: P < 0.05), but no correlation was found for serum Cu concentration. The evolution of serum Cu and Zn concentration with total age (GA + postnatal age) in the infants with a low birth weight (i.e., <1500 g) was similar to the evolution with GA. In very-low-birth-weight infants, serum levels of Cu are influenced by the maturation whereas serum Zn concentrations depends also upon the dietary intake of Zn.