Hoogenboezem T, Degenhart H J, de Muinck Keizer-Schrama S M, Bouillon R, Grose W F, Hackeng W H, Visser H K
Department of Paediatrics, Erasmus University, Rotterdam, The Netherlands.
Pediatr Res. 1989 Jun;25(6):623-8. doi: 10.1203/00006450-198906000-00014.
The aim of this longitudinal study was to examine vitamin D metabolism in exclusively breast-fed infants. The four common vitamin D metabolites--25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D [1,25(OH)2D], 24,25-dihydroxyvitamin D [24,25(OH)2D], and 25,26-dihydroxyvitamin D [25,26(OH)2D]--as well as vitamin D binding protein (DBP) were determined simultaneously in mothers and their children from delivery to several months of age. Maternal blood samples, drawn approximately 6 wk before the expected date of delivery, were also analyzed. At delivery, total vitamin D metabolites in maternal and fetal plasma were closely correlated, maternal levels being higher. Unbound (free) vitamin D metabolite concentrations were higher in fetal than in maternal plasma, with the exception of free 1,25(OH)2D levels, which were equal. This suggests a rapid placental transfer of 1,25(OH)2D. 24,25(OH)2D and 25,26(OH)2D levels both in mothers and children were closely correlated with the precursor sterol 25OHD. For 1,25(OH)2D, no correlation could be demonstrated with any of the other vitamin D metabolites. DBP concentrations in maternal plasma at the time of delivery were about twice the mean adult reference value. In cord blood, DBP levels were in the lower part of the adult reference range. Maternal total 1,25(OH)2D levels, which were twice the reference mean during pregnancy, fell sharply after delivery but free 1,25(OH)2D levels much less. Analogous to the biochemical changes in the mother, the infants' DBP levels fell after birth, as a result of the sudden disappearance of the estrogen stimulus. At the same time, the mineral supply via the placenta was cut off.(ABSTRACT TRUNCATED AT 250 WORDS)
这项纵向研究的目的是检测纯母乳喂养婴儿的维生素D代谢情况。在母亲及其孩子从分娩到几个月大的期间，同时测定了四种常见的维生素D代谢产物——25-羟基维生素D（25OHD）、1,25-二羟基维生素D [1,25(OH)₂D]、24,25-二羟基维生素D [24,25(OH)₂D] 和25,26-二羟基维生素D [25,26(OH)₂D]——以及维生素D结合蛋白（DBP）。还对预计分娩日期前约6周采集的母亲血液样本进行了分析。分娩时，母亲和胎儿血浆中的总维生素D代谢产物密切相关，母亲的水平更高。除了游离1,25(OH)₂D水平相等外，胎儿血浆中未结合（游离）维生素D代谢产物的浓度高于母亲血浆。这表明1,25(OH)₂D通过胎盘快速转运。母亲和孩子体内的24,25(OH)₂D和25,26(OH)₂D水平均与前体固醇25OHD密切相关。对于1,25(OH)₂D，未发现与其他任何维生素D代谢产物存在相关性。分娩时母亲血浆中的DBP浓度约为成人平均参考值的两倍。脐血中的DBP水平处于成人参考范围的下限。母亲的总1,25(OH)₂D水平在孕期是参考平均值的两倍，分娩后急剧下降，但游离1,25(OH)₂D水平下降幅度较小。与母亲的生化变化类似，婴儿出生后DBP水平下降，这是雌激素刺激突然消失的结果。与此同时，通过胎盘的矿物质供应被切断。（摘要截选至250词）
