RESUMO
OBJECTIVE: To evaluate the effects of early bronchopulmonary dysplasia (BPD) on calcium (Ca) metabolism and growth in very low birth weight (VLBW) infants. STUDY DESIGN: A dual-tracer, stable isotope method was used to assess Ca absorption in VLBW infants. Infants with early BPD received energy-dense feedings and mild fluid restriction. RESULTS: Sixteen of 41 preterm infants were classified as having early BPD. Fractional Ca absorption (early BPD, 58.4 ± 4.6% versus no early BPD, 50.3 ± 4.0%, P = .2), total Ca absorption (early BPD, 127 ± 14 mg/kg/d versus no early BPD, 104 ± 9 mg/kg/d, P = .9), and Ca retention (early BPD, 99.6 ± 10.0 mg/kg/d versus no early BPD, 91.0 ± 9.8 mg/kg/d, P = .2) were similar among groups. There was no significant difference in weight gain, linear growth, or head circumference growth between groups. CONCLUSIONS: The ability of VLBW infants with early BPD and fluid restriction to grow and accrete calcium is similar to those without early BPD. The use of high caloric density feedings in VLBW infants with early BPD can help achieve bone and overall growth outcomes close to those achievable in utero.
Assuntos
Displasia Broncopulmonar/complicações , Displasia Broncopulmonar/metabolismo , Cálcio/farmacocinética , Recém-Nascido de muito Baixo Peso/metabolismo , Absorção , Animais , Bovinos , Humanos , Fórmulas Infantis , Recém-Nascido , Recém-Nascido Prematuro , Terapia Intensiva Neonatal , Espectrometria de Massas/métodos , Leite , Leite Humano , Fósforo/metabolismoRESUMO
Iron absorption in adults is regulated by homeostatic mechanisms that decrease absorption when iron status is high. There are few data, however, regarding the existence of a similar homeostatic regulation in infants. We studied 2 groups of human milk-fed infants using (57)Fe (given as ferrous sulfate without any milk) and (58)Fe (given at the time of a breast-milk feeding) stable isotopes to determine whether healthy infants at risk for iron deficiency would regulate their iron absorption based on their iron status. We studied 20 Peruvian infants at 5-6 mo of age and 18 infants at 9-10 mo of age. We found no effect of infant hemoglobin concentration on iron absorption with 5-6 mo-old infants absorbing 19.2 +/- 2.1% and 9- to 10-mo-old infants absorbing 25.8 +/- 2.6% of the (57)Fe dose. For (58)Fe, 5- to 6-mo-old infants absorbed 42.6 +/- 5.0% and 9 to 10-mo-old infants absorbed 51.9 +/- 10.3%. Following log transformation, iron absorption from (57)Fe (r = -0.61, P = < 0.001) and (58)Fe (r = -0.61, P = < 0.001) were inversely correlated to serum ferritin (S-Ft). For both the (57)Fe and (58)Fe doses, infants with S-Ft <12 mg/L (n = 11) had significantly higher iron absorption than those with S-Ft >12 mg/L. We concluded that iron absorption in infants is related to iron status as assessed by serum ferritin but not hemoglobin concentration. Infants with low iron status upregulate iron absorption from breast milk at both 5-6 and 9-10 mo of age.