RESUMO
The effect of low or borderline vitamin D status on bone mineralization of exclusively breast milk-fed infants has not been studied. The low vitamin D status of Korean breast milk-fed infants may theoretically have adverse effects on bone mineralization. Assuming that bone mineral content (BMC) relates in part to vitamin D status, we hypothesized that serum 25-hydroxyvitamin D (25-OHD) concentration and BMC would be low, and serum osteocalcin concentration high, reflecting active bone turnover, in breast milk- versus formula-fed infants born in the winter. Eighteen breast milk- and 17 formula-fed infants were recruited at ages 2 to 5 months. The BMC of the lumbar1-4 spine region was measured by using dual energy x-ray absorptiometry. The BMC and serum osteocalcin levels were similar for both groups. The serum 25-OHD level was significantly lower in breast milk- than formula-fed infants; 44% of the breast milk group versus 6% of the formula group had serum 25-OHD levels less than 28 nmol/L (11 ng/ml), the lower limit of normal. The BMC did not correlate with the serum 25-OHD level. Thus BMC and serum osteocalcin levels in 2- to 5-month-old infants were not different by type of feeding, despite low vitamin D status in breast milk-fed infants. We speculate that adequate mineral absorption occurs during this period from a predominantly (vitamin D independent) passive transport mechanism.
Assuntos
Densidade Óssea , Alimentação com Mamadeira , Aleitamento Materno , Alimentos Infantis , Vitamina D/análogos & derivados , Absorciometria de Fóton , Animais , Remodelação Óssea/fisiologia , Bovinos , Feminino , Humanos , Lactente , Vértebras Lombares/diagnóstico por imagem , Masculino , Leite , Leite Humano , Osteocalcina/sangue , Vitamina D/sangueRESUMO
Seasonal differences in newborn total body bone mineral content (TBBMC) have not been studied, particularly in relation to alterations in vitamin D status in winter. In vitamin D deficiency bone resorption may be high and bone mineralization low. Bone resorption may be assessed by serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) measures. Because vitamin D supplements throughout pregnancy are uncommon in Korea, we hypothesized that in Korean winter newborns, TBBMC is low and serum ICTP high from high bone resorption and low 25-hydroxyvitamin D (25-OHD) compared with those in summer newborns. Seventy-one Korean term infants were studied prospectively in summer (July through September, n = 37) versus winter (January through March, n = 34); TBBMC was measured before 3 days of age by dual-energy x-ray absorptiometry. Significant seasonal differences were found: winter newborns had 6% lower TBBMC (least squares means +/- SD; 86.7 +/- 7.7 gm vs 93.9 +/- 7.8 gm, p = 0.0002), lower cord serum 25-OHD (10.7 +/- 8 nm vs 30 +/- 15 nm, p = 0.0001) and 1,25-dihydroxyvitamin D, and higher ICTP (96.4 +/- 20.3 microg/L vs 74.8 +/- 24 microg/L, p = 0.0002) and calcium than summer newborns. TBBMC correlated with serum 25-OHD (r = 0.243, p = 0.047) and inversely with ICTP (r = -0.333, p = 0.008). We suggest that in Korea low maternal vitamin D status in winter results in marked reduction in newborn TBBMC.
Assuntos
Densidade Óssea , Reabsorção Óssea , Cálcio/sangue , Recém-Nascido/fisiologia , Absorciometria de Fóton , Feminino , Sangue Fetal/química , Humanos , Hidroxicolecalciferóis/sangue , Recém-Nascido/sangue , Coreia (Geográfico) , Masculino , Hormônio Paratireóideo/sangue , Gravidez , Estudos Prospectivos , Estações do AnoRESUMO
Infants of diabetic mothers (IDMs) have lower bone mineral content than control subjects at birth. We measured cord blood propeptide of type I procollagen (PICP), a marker of bone formation, and telopeptide of type I collagen (ICTP), a marker of bone resorption, in 25 term IDMs and 20 term control subjects. Concentrations of ICTP were higher in IDMs than in control subjects; there was no difference in PICP concentrations. We conclude that osteoclastic activity appears to be higher in IDMs than in control subjects in utero.
Assuntos
Reabsorção Óssea/sangue , Diabetes Mellitus Tipo 1/sangue , Doenças Fetais/sangue , Gravidez em Diabéticas/sangue , Adulto , Análise de Variância , Biomarcadores/sangue , Peso ao Nascer , Densidade Óssea , Estudos de Casos e Controles , Colágeno/análise , Colágeno Tipo I , Feminino , Sangue Fetal/metabolismo , Humanos , Recém-Nascido , Fragmentos de Peptídeos/sangue , Peptídeos/análise , Gravidez , Pró-Colágeno/sangue , Estudos ProspectivosRESUMO
OBJECTIVE: To test the hypotheses that (1) bone mineral content (BMC) is similar in infants fed soy-based formula (SBF) and human milk (HM) and higher in infants fed cow milk-based formula (CBF) and (2) serum 1,25-dihydroxyvitamin D, an index of mineral sufficiency, is similar in infants fed formula and infants fed HM. DESIGN: Randomized, prospective study of formula-fed group only. SETTING: Recruitment was in a normal newborn nursery. PATIENTS: 72 infants: 10 given HM, 20 given CBF (Similac), 21 given SBF (Isomil), and 21 given SBF (Prosobee). MEASUREMENTS: BMC and 1,25-dihydroxyvitamin D levels at baseline (days 2 through 7 of life) and at 8, 16, 26, and 52 weeks of age. The BMC was similar in all groups at all times; serum 1,25-dihydroxyvitamin D levels were similar in all groups, except that they were elevated at 8, 16, and 26 weeks in those fed Prosobee. CONCLUSIONS: (1) BMC is similar in SBF-, CBF-, and HM-fed infants and (2) compensatory elevation of serum 1,25-dihydroxyvitamin D concentrations may occur in SBF-fed infants.
Assuntos
Calcificação Fisiológica/fisiologia , Alimentos Infantis , Leite Humano , Leite , Vitamina D/sangue , Animais , Estatura/fisiologia , Peso Corporal/fisiologia , Calcitriol/sangue , Cefalometria , Seguimentos , Crescimento/fisiologia , Humanos , Recém-Nascido , Fósforo/sangue , Estudos Prospectivos , Método Simples-CegoRESUMO
In small for gestational age (SGA) infants, bone mineral content (BMC) is low but the reasons are unclear and the possible relationships between calcium-regulating hormones and BMC have not been studied. We hypothesized that BMC would be lower and concentrations of serum parathyroid hormone and 1,25-dihydroxyvitamin D would be higher at birth in SGA infants than in appropriate for gestational age (AGA) infants. Forty-two term SGA infants and 126 term AGA infants, matched 1:3 specifically by gestation (+/- 1 week) and birth month, were studied prospectively. The BMC of the distal one third of the radius was measured before 3 days of age by photon absorptiometry. The BMC was lower in SGA than in AGA infants. Both SGA and AGA infants had lower BMC in summer or spring than in winter; BMC differences between groups remained significant after adjustment for season (p = 0.0001). Cord serum osteocalcin and 1,25-dihydroxyvitamin D values were lower in SGA than in AGA infants. There were no differences between groups in cord serum levels of intact parathyroid hormone, 25-hydroxyvitamin D, calcium, phosphorus, and magnesium. Relationships were positive between BMC and birth weight and were inverse between BMC and intact parathyroid hormone values. We suggest that reduced uteroplacental blood flow in SGA infants may result in reduced fetal-placental production of 1,25-dihydroxyvitamin D, which results in low BMC and low serum osteocalcin values; fetal serum parathyroid hormone values may be relatively elevated because of reduced placental mineral supply.
Assuntos
Densidade Óssea , Calcitriol/sangue , Recém-Nascido Pequeno para a Idade Gestacional/sangue , Recém-Nascido Pequeno para a Idade Gestacional/metabolismo , Osteocalcina/sangue , Osteogênese , Peso ao Nascer , Osso e Ossos/metabolismo , Cálcio/sangue , Cálcio/metabolismo , Feminino , Sangue Fetal/química , Retardo do Crescimento Fetal/metabolismo , Idade Gestacional , Humanos , Recém-Nascido , Magnésio/sangue , Masculino , Hormônio Paratireóideo/sangue , Fósforo/sangue , Placenta/metabolismo , Estações do AnoRESUMO
To determine whether amounts of vitamin D lower than recommended doses are effective in preventing rickets, 256 term infants from two northern and two southern cities in China were studied in a randomized trial of vitamin D supplementation (100, 200, or 400 IU/day) during the first 6 months of life. Cord blood and 6-month blood samples were collected and radiographs were obtained at 3 to 5 days and at 6 months of age. Cord serum 25-hydroxyvitamin D concentrations were lower in the north than in the south (5 vs 14 ng/ml (12.5 vs 35.0 nmol/L); p less than 0.01). Wrist ossification centers were less likely to be present at birth in the northern children than in the southern children (p = 0.009) and were more likely to be present in infants born in the fall who had higher cord serum concentrations of 25-hydroxyvitamin D (p = 0.04). Serum 25-hydroxyvitamin D concentrations were lower in northern children 6 months of age than in southern children (p = 0.005) and were higher with an increasing supplemental dosage of vitamin D (p less than 0.001), particularly in infants in the north. None of the infants had rickets at 6 months of age. Because of the low serum 25-hydroxyvitamin D concentrations, especially among infants in the north, it may be prudent to supplement the diet with vitamin D at a dose of 400 IU/day.
Assuntos
Raquitismo/prevenção & controle , Vitamina D/uso terapêutico , China/epidemiologia , Relação Dose-Resposta a Droga , Feminino , Sangue Fetal/química , Humanos , Hidroxicolecalciferóis/sangue , Lactente , Recém-Nascido , Masculino , Prevalência , Estudos Prospectivos , Raquitismo/epidemiologia , Vitamina D/administração & dosagemRESUMO
Seventy-one very low birth weight (less than or equal to 1500 gm) infants were studied to determine the sequential changes in serum vitamin D metabolite concentrations between infants with and without radiographically documented rickets, fractures, or both (R/F). Usual intake of vitamin D included 20 IU/kg/day from parenteral nutrition or 400 IU/day supplementation with enteral feeding. Radiographs of both forearms and serum samples were obtained at 3, 6, 9, and 12 months. Twenty-two infants had R/F. At 3 months, significantly lower mean (+/- SEM) serum phosphorus levels (4.5 +/- 0.4 vs 6.1 +/- 0.2 mg/dl), higher 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations (96 +/- 5 vs 77 +/- 4 pg/ml), and higher free 1,25-(OH)2D index (1,25-[OH]2D:vitamin D binding protein ratio; 5.2 +/- 0.3 x 10(5) vs 4.0 +/- 0.2 x 10(5] were found in the R/F group. These values returned to normal and were similar between groups on subsequent measurements. Serum calcium, magnesium, and 25-hydroxyvitamin D (25-OHD) concentrations were normal and similar between groups. In both groups, serum vitamin D binding concentrations increased initially but remained stable and normal beyond 6 months. We conclude that in very low birth weight infants with R/F, the vitamin D status (as indicated by serum 25-OHD concentrations) is normal, and that lowered serum phosphorus levels, higher serum 1,25-(OH)2D levels, and a higher free 1,25-(OH)2D index support the thesis that mineral deficiency (especially of phosphorus) may be important in the pathogenesis of R/F in small preterm infants.