RESUMO
OBJECTIVE: To monitor ultraviolet B light exposure in human milk-fed infants both with and without supplemental vitamin D2, and to measure longitudinally the bone mineral content, growth, and serum concentrations of calcium, phosphorus, 25-hydroxyvitamin D3, 25-hydroxyvitamin D2, 1,25-dihydroxyvitamin D, and parathyroid hormone. DESIGN: Longitudinal, randomized, double-blind, placebo-controlled study of 6 months' duration. SETTING: Patients from private pediatric practice, Madison, Wisconsin. PATIENTS: Sequential sampling of 46 human milk-fed white infants; 24 received 400 IU/day of vitamin D2, and 22 received placebo. An additional 12 patients were followed who received standard infant formula. Eighty-three percent of patients completed a full 6 months of the study. MEASUREMENTS AND RESULTS: Ultraviolet B light exposure and measurements of growth did not differ between groups. At 6 months, the human milk groups did not differ significantly in bone mineral content or serum concentrations of parathyroid hormone or 1,25-dihydroxyvitamin D, although total 25-hydroxyvitamin D values were significantly less in the unsupplemented human milk group (23.53 +/- 9.94 vs 36.96 +/- 11.86 ng/ml; p less than 0.01). However, 25-hydroxyvitamin D3 serum concentrations were significantly higher in the unsupplemented human milk-fed group compared with the supplemented group (21.77 +/- 9.73 vs 11.74 +/- 10.27 ng/ml, p less than 0.01) by 6 months of age. CONCLUSION: Unsupplemented, human milk-fed infants had no evidence of vitamin D deficiency during the first 6 months of life.
Assuntos
Osso e Ossos/análise , Aleitamento Materno , Calcifediol/sangue , Calcitriol/sangue , Ergocalciferóis/análogos & derivados , Ergocalciferóis/administração & dosagem , Crescimento , Minerais/análise , Raios Ultravioleta , 25-Hidroxivitamina D 2 , Cálcio/sangue , Método Duplo-Cego , Exposição Ambiental , Ergocalciferóis/sangue , Feminino , Humanos , Recém-Nascido , Masculino , Hormônio Paratireóideo/sangue , Fósforo/sangue , Distribuição Aleatória , Deficiência de Vitamina D/diagnósticoRESUMO
The circulating concentrations of calcium, phosphorus, and vitamin D metabolites were measured in 25 infants (fifteen to 30 days of age) with congenital hypothyroidism before treatment or during the first 6 months of thyroxine therapy. Five of the children before treatment and four during the early 3 months of treatment had mild hypercalcemia (10.8 to 12.4 mg/dl). Hypercalcemia before treatment did not appear to be related to the vitamin D status of the infant nor to an alteration in vitamin D metabolism, but to the presence of a residual thyroid secretion. In contrast, hypercalcemia during thyroxine therapy was related to vitamin D supplementation, even though the serum calcium concentration could not be correlated with the circulating concentration of any of the vitamin D metabolites assayed and obvious changes in vitamin D metabolism could not be demonstrated.
Assuntos
Hipotireoidismo Congênito , Hipercalcemia/complicações , Hormônios Tireóideos/sangue , Vitamina D/metabolismo , 24,25-Di-Hidroxivitamina D 3 , 25-Hidroxivitamina D 2 , Fosfatase Alcalina/sangue , Calcitriol/sangue , Cálcio/sangue , Di-Hidroxicolecalciferóis/sangue , Ergocalciferóis/administração & dosagem , Ergocalciferóis/análogos & derivados , Ergocalciferóis/sangue , Ergocalciferóis/uso terapêutico , Humanos , Hipercalcemia/sangue , Hipotireoidismo/sangue , Hipotireoidismo/complicações , Hipotireoidismo/diagnóstico , Hipotireoidismo/tratamento farmacológico , Recém-Nascido , Fósforo/sangue , Tireotropina/sangue , Tiroxina/administração & dosagem , Tiroxina/uso terapêutico , Fatores de TempoRESUMO
We assessed whether modification of vitamin D nutritional status during the last trimester of pregnancy affects maternal and neonatal calcium homeostasis. At the end of the first trimester, 40 pregnant women were randomly assigned to either of two groups, and blood taken to assess the basal values of Ca, Pi, Mg, iPTH, 25-OHD, and 1,25(OH)2D. From the sixth month on, group 1 (+D) received 1000 IU vitamin D3 daily; group 2 (-D) served as control. At the time of delivery, maternal serum 25-OHD was higher in the +D group (P less than 0.0005). Ca, Pi, iPTH, and 1,25(OH)2D were not affected. At term, venous cord 25-OHD levels were also higher in the +D group (P less than 0.0005), and 1,25(OH)2D levels slightly lower (P less than 0.05), but neither Ca, Pi, nor iPTH differed between the two groups. Serum CaT dropped significantly (P less than 0.002) at 4 days of age in the infants from both groups, although to a lesser extent in these from the +D group (P less than 0.05). Circulating iPTH increased in both groups. Serum 25-OHD remained low in the -D group, and dropped slightly in the +D group; 1,25(OH)2D remained stable during the first 4 days of life in the -D group, and increased in the +D group (P less than 0.001). Our data demonstrate the importance of providing adequate maternal vitamin D stores to ensure better perinatal handling of calcium. This is of particular importance for populations at risk for hypovitaminosis D.
Assuntos
Cálcio/sangue , Recém-Nascido , Gravidez , Vitamina D/uso terapêutico , 25-Hidroxivitamina D 2 , Ergocalciferóis/análogos & derivados , Ergocalciferóis/sangue , Feminino , Sangue Fetal/análise , Homeostase , Humanos , Magnésio/sangue , Hormônio Paratireóideo/sangue , Fosfatos/sangue , Distribuição AleatóriaRESUMO
Although abnormalities of calcium and vitamin D metabolism are recognized in children with nephrotic syndrome, longitudinal observations are not available in these patients during periods of relapse and remission. We report observations in 58 children (mean age 10.1 years) with nephrotic syndrome and normal glomerular filtration rate. Hypocalcemia, modest hyperparathyroidism, and strikingly low calcidiol levels were identified during episodes of relapse. Most alterations were transient, and normalized on remission. The plasma concentration of calcitriol, the most active metabolite of vitamin D, was found to be normal in both relapse and remission. In the presence of hypocalcemia and hyperparathyroidism, however, normal plasma calcitriol levels in relapse may be inappropriately low and reflect a state of relative deficiency. Concurrent glucocorticoid therapy did not modify the results. A corollary of our observations is that children with relapsing or protracted nephrotic syndrome are at risk of developing metabolic bone disease, even without impairment of glomerular filtration rate.
Assuntos
Cálcio/metabolismo , Síndrome Nefrótica/metabolismo , Vitamina D/metabolismo , 25-Hidroxivitamina D 2 , Adolescente , Adulto , Criança , Pré-Escolar , Ergocalciferóis/análogos & derivados , Ergocalciferóis/sangue , Taxa de Filtração Glomerular , Humanos , Hiperparatireoidismo/etiologia , Hipocalcemia/etiologia , Hipocalcemia/metabolismo , Síndrome Nefrótica/complicações , Hormônio Paratireóideo/sangue , RecidivaRESUMO
To assess mineral metabolism in patients with cystic fibrosis and to study the effects of season and sunlight exposure on generation of vitamin D metabolites, we quantified serum levels of calcidiol and calcitriol, other measures of bone metabolism, and radiographic bone mass in 20 adolescents and young adults with CF and 20 age-matched normal volunteers. Levels of calcidiol were lower in patients with CF than in controls and lower in Massachusetts than in Arizona in both study groups. Controls in Arizona had higher (P less than 0.05) levels of calcitriol than in Massachusetts throughout the year. All control subjects in both states had higher levels of calcitriol than did patients with CF. Patients in Massachusetts had significantly lower levels of calcitriol in winter than in summer. Summer levels of calcitriol in CF were significantly higher in Massachusetts than in Arizona; during winter, lower levels were found in Massachusetts than in Arizona. Mean bone density in patients with CF was 88% and 89% of normal American standards in Massachusetts and Arizona, respectively. These data indicate a seasonal, sunlight-related influence on levels of vitamin D metabolites in patients with CF receiving approximately 1000 IU vitamin D per day. Older patients with CF with progressively diminishing sunlight exposure may be at increased risk for development of osteopenia. The detected radiographic abnormalities of bone mineralization may also be related to malabsorptive deficiencies of calcium and phosphorus.
Assuntos
Calcitriol/sangue , Fibrose Cística/sangue , Ergocalciferóis/análogos & derivados , Estações do Ano , Luz Solar , 25-Hidroxivitamina D 2 , Adolescente , Adulto , Arizona , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/metabolismo , Cálcio/sangue , Criança , Cromatografia Líquida de Alta Pressão , Fibrose Cística/metabolismo , Ergocalciferóis/sangue , Feminino , Humanos , Masculino , Massachusetts , Minerais/metabolismo , RadiografiaRESUMO
A cross-sectional study was carried out of 412 healthy and 226 chronically malnourished children in Recife, Brazil. Anthropometric measurements, x-rays of hands and wrists, and biochemical data related to skeletal growth were obtained. Levels of plasma 25 hydroxyvitamin D were measured in both groups of children and both showed higher concentrations than those reported for normal European children. The high levels of 25 hydroxyvitamin D found in these two groups of Brazilian children are probably the result of the intense solar radiation in this part of Brazil and argue against the diet being an important source of vitamin D in poorly nourished children. Some bone abnormalities were seen in the underprivileged group of children but in view of our findings these were more likely to be a result of protein-energy malnutrition than rickets.
Assuntos
Fenômenos Fisiológicos da Nutrição Infantil , Distúrbios Nutricionais/metabolismo , Vitamina D/sangue , 25-Hidroxivitamina D 2 , Adolescente , Peso Corporal , Desenvolvimento Ósseo , Osso e Ossos/diagnóstico por imagem , Brasil , Criança , Ergocalciferóis/análogos & derivados , Ergocalciferóis/sangue , Feminino , Humanos , Masculino , Distúrbios Nutricionais/sangue , Distúrbios Nutricionais/epidemiologia , Radiografia , Fatores SocioeconômicosRESUMO
Serum calcidiol, calcitriol, and 24,25-dihydroxyvitamin D concentrations were measured in 20 children with vitamin D-deficiency rickets. Vitamin D metabolite concentrations were measured in 17 of 20 patients before treatment and in 14 of 20 patients after vitamin D administration. Conclusions are as follows. (1) Before treatment, serum calcidiol seems to be the best criterion of D deficiency, as it was low (less than 8 ng/ml) in 15 of 17 studied children, whereas calcitriol and 24,25-dihydroxyvitamin D concentrations ranged from undetectable to high values (350 pg/ml and 5.9 ng/ml, respectively). (2) Low calcidiol concentrations may occur despite recent vitamin D intake: low serum values were found in children given vitamin D2 up to two months after the onset of therapy (50 micrograms/day). (3) Elevated calcitriol serum concentrations were observed in all children after initiation of vitamin D therapy; these high concentrations persisted for four weeks or more, even after normalization of serum calcium, phosphorus, and parathyroid hormone values. (4) Healing of biochemical abnormalities can occur even in children with low circulating concentrations of calcidiol and 24,25-dihydroxyvitamin D.
Assuntos
Calcitriol/sangue , Ergocalciferóis/análogos & derivados , Raquitismo/sangue , 25-Hidroxivitamina D 2 , Cálcio/sangue , Criança , Pré-Escolar , Ergocalciferóis/sangue , Ergocalciferóis/uso terapêutico , Feminino , Humanos , Lactente , Masculino , Raquitismo/tratamento farmacológicoAssuntos
Cistinose/tratamento farmacológico , Nefropatias/tratamento farmacológico , Vitamina D/metabolismo , Calcifediol/sangue , Calcifediol/uso terapêutico , Calcitriol/sangue , Calcitriol/uso terapêutico , Criança , Cistinose/sangue , Cistinose/metabolismo , Di-Hidrotaquisterol/sangue , Di-Hidrotaquisterol/uso terapêutico , Ergocalciferóis/análogos & derivados , Ergocalciferóis/sangue , Ergocalciferóis/uso terapêutico , Humanos , Nefropatias/sangue , Nefropatias/metabolismo , Vitamina D/sangueRESUMO
To determine the calcium and bone mineral status of lactating adolescents, we compared 12 lactating adolescents with 11 nonlactating adolescents, 11 lactating adults, and 11 nulliparous adolescent control subjects. At two and 16 weeks, there were no differences in maternal serum concentrations of calcium, phosphorus, alkaline phosphatase, or calcidiol (25-hydroxyvitamin D). The bone mineral content at two weeks among the four groups was not different, but at 16 weeks the lactating adolescents' bone mineral content was lower than that in the other groups. The lactating adolescents' bone mineral content was decreased between two and 16 weeks (1.049 +/- 0.088 vs 0.887 +/- 0.054 gm/cm; P less than 0.02). Dietary intakes were similar among the groups for calories, protein, vitamin D, calcium, and phosphorus. However, only three of ten lactating adolescents met the recommended dietary allowance for calcium or phosphorus (1,600 mg/day), whereas eight of ten nonlactating adolescents, six of seven lactating adults, and seven of ten adolescents control subjects met the recommended dietary allowance for calcium or phosphorus (P less than 0.05). Our data suggest that during 16 weeks of lactation, the adolescent mother may be at risk for bone demineralization because of low dietary intakes of calcium or phosphorus.