Effects of different doses of vitamin D on serum calcium, phosphorus, alkaline phosphatase and 25-hydroxyvitamin D levels in very low birth weight infants / 中华围产医学杂志

ABSTRACT

Objectives To understand the effects of different doses of vitamin D supplementation on serum calcium,phosphorus,alkaline phosphatase and 25-hydroxyvitamin D levels in very low birth weight infants (VLBWI) and to provide guidance for early prevention of metabolic bone disease in VLBWI.Methods A total of 90 VLBWI hospitalized in the Department of Neonatology,Huzhou Maternal and Child Healthcare Hospital between January 2014 and January 2016 were enrolled and randomly divided into two groupshighdose group and low dose group.High-dose group was given vitamin D 900 U/d orally and low-dose group was given 400 U/d since the eighth day after birth.Serum calcium,phosphorus and alkaline phosphatase levels were detected at 1,7,21 and 42 days of age and serum 25-hydroxyvitamin D levels were detected at 7,21and 42 days of age.Two-sample t-test,Chi-square test,one-way analysis of variance and LSD or Dunnett's T3 test were used for statistical analysis.Results No significant differences in serum calcium,phosphorus and alkaline phosphatase levels were found between the two groups at 1 and 7 days of age,nor were found in serum 25-hydroxyvitamin D level at 7 days of age (all P＞0.05).At 21 days of age,high dose group had higher serum calcium,phosphorus and 25-hydroxyvitamin D levels than low-dose group [(2.38 ± 0.09) vs (2.04 ± 0.15) mmol/L,t=2.421;(1.80±0.50) vs (1.71 ±0.60) mmol/L,t-0.637;(45.58± 18.43) vs (42.53± 16.33) nmol/L,t=0.421],but lower alkaline phosphatase level [(505.12± 185.61) vs (588.32± 168.72) U/L,t=5.314] (all P＜0.05).The same trends were found at 42 days of age.In high-dose group,serum calcium level increased at 7,21 and 42 days of age as compared with that at 1 day of age [(2.43±0.13),(2.38±0.09),(2.39±0.08) vs (2.06±0.57) mmol/L];serum phosphorus level at 7 days of age was lower than that at 1,21 and 42 days of age [(1.31 ±0.26) vs (1.89±0.39),(1.80±0.50),(1.98±0.30) mmol/L];serum alkaline phosphatase level at 7,21 and 42 days of age was higher than that at 1 day of age [(475.18± 133.73),(505.12± 185.61),(538.43 ± 168.16) vs (296.15 ± 99.41) U/L] and a significant increase was observed at 42 days of age as compared with that at 7 days of age;serum 25 hydroxyvitamin D level at 21 days of age was higher than that at 7 days of age,and that at 42 days of age was higher than that at 7 and 21 days of age [(73.55±23.65) vs (30.63± 12.66) and (45.58 ± 18.43) nmol/L];the differences were all statistically significant (LSD or Dunnett's T3 test,all P＜0.05).Conclusions Vitamin D supplementation from the eighth day after birth can improve calcium and phosphorus metabolism in VLBWI and the dose of 900 U/d is more effective than 400 U/d.