摘要：Background The pivotal role of vitamin D (vit D) in skeletal health is well known. Neonatal vit D storage at birth is dependent on maternal levels, and newborns receive 50–70% of their mother’s 25-hydroxyvitamin D [25(OH)D]. Deficiency of vit D can lead to prematurity bone disease, with an incidence of up to 55% in infants weighing Methods/design Preterm infants born at 24–32 weeks of gestation will be recruited within the first 7 days of life. Depending on the type of feeding, and after reaching partial enteral feeding or at 7 days of life, vit D supplementation will consist of 500 IU and an additional 150–300 IU/kg included in human milk fortifiers (if fed exclusively with breast milk) or 190 IU/kg in milk formulas. Subjects will be randomised to either monitored (with an option of dose modification based on 25(OH)D levels as per protocol) or standard therapy up to 52 weeks of post-conceptional age (PCA). The primary outcome measure will be the number of neonates with deficiency or excess levels of 25(OH)D at 40 ±2 weeks of PCA. Additional 25(OH)D levels will be measured at birth, at 4 and 8 weeks of age, and/or at 35 and 52 ±2 weeks of PCA. Secondary objectives will include the incidence of osteopenia, nephrocalcinosis and nephrolithiasis. Serum parameters of calcium phosphorus metabolism will also be measured. Discussion Despite multiple years of research and numerous publications, there is still a lack of consensus in regard to how much vit D infants should receive and how long they should receive it. Because 80% of calcium and phosphorus placental transfer occurs between 24 and 40 weeks of gestation, preterm infants are especially prone to adverse effects of vit D insufficiency. However, both inadequate and excessive amounts of vit D may be unsafe and lead to serious health issues. The results of our study may shed new light on these concerns and contribute to optimising vit D supplementation. Trial registration ClinicalTrials.gov, NCT03087149 . Registered on 15 March 2017.
