title: Characterization of the vitamin A transport in preterm infants after repeated high-dose vitamin A injections.
abstract: OBJECTIVE
  Preterm infants have low vitamin A stores at birth, and parenteral administration of high-dose vitamin A reduces pulmonary morbidity. The aim was to characterize vitamin A transport and status.
  
  
  METHODS
  Prospective study of 69 preterm infants (median birth weight 995 g, gestational age 28 weeks), in which 51 received 5000 IU vitamin A three times per week intramuscular (i.m.) for 4 weeks and 18 infants without i.m. vitamin A served as controls. Serum retinol, retinyl palmitate, total retinol-binding protein 4 (RBP4), retinol-unbound RBP4 (apo-RBP4) and transthyretin concentrations were determined at days 3 (D3) and 28 (D28) of life.
  
  
  RESULTS
  D3 retinol concentrations were low for the entire group (382 (285/531) nmol/l; median/interquartile range) and unrelated to gestational age. D28 retinol was unchanged in controls (382 (280/471) nmol/l), but increased in the vitamin A group (596 (480/825) nmol/l; P<0.001). A similar pattern was observed for RBP4. The calculated retinol-to-RBP4 ratio rose in vitamin A infants (D3: 0.81 (0.57/0.94), D28: 0.98 (0.77/1.26); P<0.01) but not in controls. In the vitamin A group, the retinol-to-RBP4 ratio was >1 in 15% of all infants on D3 and in 45% of infants on D28, but was ⩽1 in all, but one, controls on D28.
  
  
  CONCLUSIONS
  In preterm infants receiving a 4-week course of high-dose i.m. vitamin A, serum retinol concentrations increased by 55%, with molar concentrations of retinol exceeding those of RBP4 in 45% of the infants suggesting transport mechanisms other than RBP4.
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany.
authors.forename: A C
authors.initials: AC
authors.lastname: Longardt
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Potsdam, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schmiedchen
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Potsdam, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Raila
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Potsdam, Germany.
authors.forename: F J
authors.initials: FJ
authors.lastname: Schweigert
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Obladen
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Bührer
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Loui
mesh_terms: D004224:Diterpenes; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D007273:Injections, Intramuscular; D011228:Prealbumin / Q000032:analysis; D011446:Prospective Studies; D054839:Retinol-Binding Proteins, Plasma / Q000032:analysis; D000084562:Retinyl Esters; D018709:Statistics, Nonparametric; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology*
chemical_list: D004224:Diterpenes; D011228:Prealbumin; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate