title: Vitamin D metabolism in the premature newborn: A randomized trial.
abstract: Vitamin D status during infancy has been associated with important pediatric health outcomes; however concentrations of many vitamin D metabolites in premature infants are not yet described. The objective of this study was to evaluate concentrations of 25(OH)D3, 24,25(OH)2D3, and 3-epi-25(OH)D3 in premature infants.
  
  
  
  32 infants <32 weeks gestation were randomized to receive 400 or 800IU/day of vitamin D3 orally. Vitamin D metabolites from serum obtained monthly were analyzed in triplicate using a novel, very sensitive Liquid Chromatography-Tandem Mass Spectrometry-based method. Statistical analysis was conducted using the Fisher's exact test, Wilcoxon Rank Sum test, and Spearman correlation coefficients. Measurements over time were fit with linear mixed effect models. A p-value of <0.05 was considered statistically significant.
  
  
  
  Mean serum 25(OH)D3 concentrations in cord blood were 17.3 ng/mL; mean 3-epi-25(OH)D3 were 1.3 ng/mL, mean 24,25(OH)2D3 were 1.4 ng/mL. Both 25(OH)D3 and 3-epi-25(OH)D3 increased significantly over time, and the percent of total 25(OH)D3 concentration that was 3-epi-25(OH)D3 also increased significantly (7.2% vs. 29.7%, p < 0.0001 for cord blood vs. 8 weeks). Serum 25(OH)D3:24,25(OH)2D3 ratios at weeks 4 and 8 were higher than ratios reported in older children and adults.
  
  
  
  Vitamin D metabolism in infants appears to have distinct differences from adults. Vitamin D supplementation was effective in raising 25(OH)D3 concentrations; however significant increases in 3-epi-25(OH)D3 also occurred. Increased 25(OH)D3: 24,25(OH)2D3 ratios in premature infants may be due to immature expression of CYP24A1. Further work is necessary to determine if there are developmental advantages to this unique vitamin D metabolism.
authors: University of Nebraska Medical Center, School of Allied Health Professionals, Medical Nutrition Education, 984045 Nebraska Medical Center, Omaha, NE 68198-4045, USA. Electronic address: ckhanson@unmc.edu.
authors: Corrine
authors: C
authors: Hanson
authors: Queen's University, Department of Biomedical and Molecular Sciences Kingston, Ontario K7L 3N6, Canada. Electronic address: gj1@queensu.ca.
authors: Glenville
authors: G
authors: Jones
authors: University of Nebraska Medical Center, College of Public Health, 984375 Nebraska Medical Center, Omaha, NE 68198-4375, USA. Electronic address: elyden@unmc.edu.
authors: Elizabeth
authors: E
authors: Lyden
authors: Queen's University, Department of Biomedical and Molecular Sciences Kingston, Ontario K7L 3N6, Canada. Electronic address: Martin.kaufmann@queensu.ca.
authors: Martin
authors: M
authors: Kaufmann
authors: Creighton Osteoporosis Research Center, Creighton University 601 N 30th Street, Omaha, NE 68131, USA. Electronic address: larmas@creighton.edu.
authors: Laura
authors: L
authors: Armas
authors: University of Nebraska Medical Center, Pediatrics, 981205 Nebraska Medical Center, Omaha, NE 68198-1205, USA. Electronic address: alanders@unmc.edu.
authors: Ann
authors: A
authors: Anderson-Berry
mesh_terms: D000284:Administration, Oral; D002762:Cholecalciferol / Q000097:blood*; D002853:Chromatography, Liquid; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005312:Fetal Blood / Q000737:chemistry / Q000187:drug effects; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008297:Male; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D; D002762:Cholecalciferol
keywords: Infant nutrition; Prematurity; Vitamin D; Vitamin D metabolism