RESUMO
To determine the intravenous zinc and copper intakes required to build up body stores in the preterm infant and achieve positive retention in full-term infants, balance studies were completed in 38 preterm, full-term, and full-term SGA infants who received complete intravenously delivered nutrient formulations excluding zinc and copper. Zinc as ZnSo4 and copper as CuCl2 were then added to individual infants' formulations, with intakes ranging from 91 to 824 micrograms/kg/day (zinc) and 8 to 92 micrograms/kg/day (copper). Samples of infusate as well as urine, stool, and aspirate were collected for 72 hours and analyzed for zinc and copper by atomic absorption spectrophotometry. Zinc and copper retention correlated significantly with intake (r = 0.89; 0.82, P less than 0.01) and were independent of gestational age, postnatal age, and birth weight. In full-term and full-term SGA infants, intakes of zinc at greater than 150 and copper at greater than 16 micrograms/kg/day were adequate to replace ongoing losses and prevent acute deficiencies. The dosage for copper is similar to the current recommendation of the American Medical Association; the zinc dosage is 50% higher. Preterm infants receiving intakes of zinc at 438 and copper at 63 micrograms/kg/day achieve in utero retention rates. These dosages are significantly higher than AMA recommendations. Both combinations can be delivered by peripheral or central line without complications.