title: Assessment of vitamin A nutritional status in newborn preterm infants.
abstract: OBJECTIVE
  This study assessed the vitamin A nutritional status of preterm infants determined by the vitamin A relative dose-response test (RDR) compared with serum levels of vitamin A, retinol-binding protein (RBP), transthyretin (TTR), and retinol relations with carrier proteins.
  
  
  METHODS
  Serum levels of retinol, RBP, and TTR and retinol/RBP, retinol/TTR, and RBP/TTR molar ratios were determined in 120 infants at 7 d and in 92 at 28 d. For the determination of the performance of the tests, the RDR was considered the reference method. The sensitivity and specificity for all possible cutoff values were determined by constructing receiver operator characteristic curves. The areas under the curves were used to estimate the overall accuracy of the tests. The best cutoff values to be used for the calculation of sensitivity and specificity were determined with 95% confidence intervals.
  
  
  RESULTS
  RDR indicated vitamin A deficiency in 60% of the infants at 7 d and in 51.1% at 28 d. In the receiver operator characteristic curves, the best area under the curve was 0.710 obtained for serum retinol at 28 d of postnatal age and considered moderately accurate. The least inadequate cutoff level was set at 25 mg/dL, but no value was considered adequate due to low sensitivity and/or low specificity.
  
  
  CONCLUSIONS
  Compared with RDR, the determination of serum levels of retinol, RBP, and TTR and their molar ratios are not adequate to assess nutritional vitamin A status in preterm infants.
authors.affiliation: Department of Pediatrics, School of Medicine of Santa Maria, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
authors.forename: Angela Regina Maciel
authors.initials: AR
authors.lastname: Weinman
authors.forename: Salim Moysés
authors.initials: SM
authors.lastname: Jorge
authors.forename: Antonio Roberto
authors.initials: AR
authors.lastname: Martins
authors.forename: Maria das Graças Elias
authors.initials: Md
authors.lastname: de Assis
authors.forename: Francisco Eulógio
authors.initials: FE
authors.lastname: Martinez
authors.forename: José Simon
authors.initials: JS
authors.lastname: Camelo
mesh_terms: D019540:Area Under Curve; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007227:Infant Nutritional Physiological Phenomena / Q000502:physiology*; D007231:Infant, Newborn; D008297:Male; D015596:Nutrition Assessment; D009752:Nutritional Status; D011228:Prealbumin / Q000032:analysis / Q000378:metabolism; D011446:Prospective Studies; D012016:Reference Values; D012177:Retinol-Binding Proteins / Q000032:analysis / Q000378:metabolism; D012680:Sensitivity and Specificity; D014801:Vitamin A / Q000097:blood*; D014802:Vitamin A Deficiency / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D011228:Prealbumin; D012177:Retinol-Binding Proteins; D014801:Vitamin A