Vitamin D Status In Preterm Infants And The Effects Of Calcitriol On Bone Metabolism And Diseases In VLBWI

Part I Vitamin D status in preterm infantsObjective:To investigate the vitamin D status in preterm infants and its related factors by measuring serum 25-hydroxyvitamin D[25-（OH）D]level in preterm infants with dif-ferent gestational ages within 24 hours after birth.Methods:256 preterm infants were selected from the neonatal intensive care unit（NICU）in the Affiliated Hospital of Qingdao University from January 2019 to October 2019.Ac-cording to the gestational age,they were divided into four groups:<28w（n=13）,28-31⁺⁶w（n=79）,32-33⁺⁶w（n=64）and≥34w（n=100）.Blood samples（2 ml）were taken to detect the serum 25-（OH）D level with electrochemical luminescence immunity analyzer within 24hours after birth.According to serum 25-（OH）D level,they were divided into four status:severe vitamin D deficiency（<10 ng/ml）,moderate vitamin D deficiency（≥10-<20 ng/ml）,vitamin D insufficiency（≥20-≤30 ng/ml）and vitamin D sufficiency（>30 ng/ml）.Thenperform statistical analysis.Results:1.The median serum 25-（OH）D level of preterm infants at birth was 11.10ng/ml（range 2.10～43.45 ng/ml）;the rates of severe vtimin D deficiency,moderate defi-ciency,insufficiency and sufficiency were 42.58%,44.92%,10.16%,and 2.34%,respec-tively.2.The median serum 25-（OH）D level was 8.07 ng/ml,10.26 ng/ml,12.21 ng/ml,11.59ng/ml in<28w group,28-31⁺⁶w group,32-33⁺⁶w group and≥34w group,respectively.There was no significant statistical difference among four groups（P>0.05）.The rates of severe vitamin D deficiency in the four groups were 69.23%,45.57%,32.81%,and 43.00%,respectively;the rates of moderate vitamin D deficiency were 30.77%,46.84%,48.44%and 43.00%,respectively;the rates of vitamin D insufficiency were 0.00%,7.59%,15.63%,and 10.00%respectively;the rates of vitamin D sufficiency were 0.00%,0.00%,3.13%,and 4.00%,respectively.There was no statistically significant difference among four groups（P>0.05）.3.Birth weight,head circumference and length were positively correlated with vitamin D status in preterm infants,the Spearman correlation coefficient was 0.136,0.195,0.202,respectively,P<0.05.Conclusions:1.Preterm infants are born with low 25-（OH）D level and widespread vit-amin D deficiency,nearly half of them are in severe vitamin D deficiency.2.There is no significant correlation between vitamin D status and the gestational age.3.Intrauterine development in preterm infants is positively correlated with vitamin D status at birth.Part Ⅱ The effects of calcitriol on bone metabolism and diseases in VLBWIObjective: To explore the effects of active vitamin D preparation on bone metabolism and diseases in very low birth weight infants（VLBWI）,through a clinical controlled study of calcitriol and vitamin D3 supplementation.Methods: A prospective observational study was conducted in the NICU at the Affiliated Hospital of Qingdao University between January and October 2019.The VLBWI whose parents signed an informed consent form was included in the calcitriol group（n = 40）,the next VLBWI admitted to the NICU following the calcitriol group was included in the control group（n = 40）.Both groups of premature infants were given vitamin AD（vitamin D 500 IU,vitamin A 1500IU）1 capsule per day after gestational tolerance（calcitriol group 10.26 ± 3.76 days,control group 10.65 ± 5.20 days）,the calcitriol group added calcitriol 0.125 ug per day and the control group added vitamin D3 400 IU per day.Serum 25-（OH）D,alkaline phosphatase（ALP）,calcium and phosphorus levels were measured within 24 h and 1 month after birth.The length,weight and head circumference were measured at 40 weeks of corrected gestational age.The clinical data of two groups during hospitalization were recorded and statistically processed.Results: 1.Comparability analysis:（1）There was no statistically significant difference in the basic information（such as gestational age,birth weight）and serum 25-（OH）D,ALP,calcium,phosphorus level at birth between the two groups（P> 0.05）;（2）There was no statistically significant difference in the duration of TPN,feeding type,calcium and phosphorus intake,the time of starting vitamin D preparation and the duration of caffeine use between the two groups during hospitalization.2.Comparison of bone metabolic indexes: There was no significant difference in serum 25-（OH）D level,vitamin D status,serum ALP,serum calcium and phosphorus levels between the two groups at 1 month after birth（P> 0.05）;There was no significant difference in length,weight,and head circumference between the two groups at 40 weeks of corrected gestational age（P> 0.05）.3.Comparison of perinatal comorbidities: The duration of mechanical ventilation and the length of hospital stay in the calcitriol group were shorter than those in the control group（P <0.05）;The BPD severity was slighter than that in the control group（P <0.05）;The incidence of sepsis was lower than that in the control group（P <0.05）.There was no significant difference in noninvasive ventilation time and the incidence of neonatal respiratory distress syndrome,metabolic bone disease and bronchopulmonary dysplasia between the two groups（P> 0.05）.Conclusions: 1.There is no significant difference in the effects of calcitriol supplementation and vitamin D3 supplementation on bone metabolism in very low birth weight infants.2.Calcitriol supplementation in very low birth weight infants can not only shorten the duration of mechanical ventilation and hospital stay,but also reduce the severity of BPD and the incidence of sepsis.