Serum zinc and copper concentrations in low birth weight infants during first three months of life: correlation to birth weight and different feedings.

Serum zinc (Zn) and copper (Cu) concentrations were measured in infants weighing 740 g to 2,500 g at birth. They were divided into three groups depending on their birth weight; Group I ranged from 740 to 1,500 g (N = 35), Group II from 1,501 to 2,000 g (N = 26), and Group III from 2,001 to 2,500 g (N = 19). They were fed breast milk (N = 24), commercially available non-supplemented formula with low Zn and low Cu content (N = 42), or Zn- and Cu-supplemented formula (N = 14). Serum Zn levels of breast fed infants were apparently higher than those of the other two different formula fed infants, the difference being significant at 1 month of age in Group I. After the decline of serum Zn level during the first month of life, the level in Groups II and III remained unchanged, whereas the level in Group I further declined progressively until 3 months of age. An incidence of hypozincemia (0.65 micrograms/ml) was highest in Group I, medium in Group II, and lowest in Group III. The serum Cu level was elevated progressively after birth in all groups, but the mean level was consistently highest in Group III, medium in Group II and lowest in Group I. No difference in serum Cu level was found among the infants with different feedings.