The Quandary of vitamin D in the newborn infant
1983
Tsang, Reginald C.
Special features of vitamin D metabolism in the newborn infant are examined; these include: perinatal 1,25-dihydroxy-vitamin D (1,25-DHD) metabolism, vitamin D metabolism of breast-fed infants, and the problem of osteopenia of prematurity. In perinatal vitamin D metabolism, calcium (Ca) and phosphorous (P) are actively transported across the placenta from mother to fetus. Several factors (e.g., maternal loss of Ca and P) increase the hormonal form of vitamin D (1,25-DHD) which increases Ca and P retention, but the role of placental (1,25-DHD) production is unclear. Hence, the maternal-fetal transfer of vitamin D and its metabolites in humans is uncertain. In addition, very little is known about skin synthesis of vitamin D in infancy. It has been suggested that vitamin D metabolic defects may contribute to the development of osteopenia or rickets, in preterm infants, but recent studies indicate that vitamin D is well-absorbed and metabolized in such infants. Recent research findings concerning vitamin D in newborns are reviewed, including the ability for human milk vitamin D to prevent rickets. (wz)
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