title: Effect of vitamin A supplementation on the urinary retinol excretion in very low birth weight infants.
abstract: Despite high-dose vitamin A supplementation of very low birth weight infants (VLBW, <1500 g), their vitamin A status does not improve substantially. Unknown is the impact of urinary retinol excretion on the serum retinol concentration in these infants. Therefore, the effect of high-dose vitamin A supplementation on the urinary vitamin A excretion in VLBW infants was investigated. Sixty-three VLBW infants were treated with vitamin A (5000 IU intramuscular, 3 times/week for 4 weeks); 38 untreated infants were classified as control group. On days 3 and 28 of life, retinol, retinol-binding protein 4 (RBP4), glomerular filtration rate, proteinuria, and Tamm-Horsfall protein were quantified in urine. On day 3 of life, substantial retinol and RBP4 losses were found in both groups, which significantly decreased until day 28. Notwithstanding, the retinol excretion was higher (P < 0.01) under vitamin A supplementation as compared to infants of the control group. On day 28 of life, the urinary retinol concentrations were predictive for serum retinol concentrations in the vitamin A treated (P < 0.01), but not in the control group (P = 0.570).
  
  
  CONCLUSIONS
  High urinary retinol excretion may limit the vitamin A supplementation efficacy in VLBW infants. Advanced age and thus postnatal kidney maturation seems to be an important contributor in the prevention of urinary retinol losses.
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany. bettina.schmiedchen@uni-potsdam.de.
authors.forename: Bettina
authors.initials: B
authors.lastname: Schmiedchen
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany. Ann-Carolin.Longardt@charite.de.
authors.forename: Ann Carolin
authors.initials: AC
authors.lastname: Longardt
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany. Andrea.Loui@charite.de.
authors.forename: Andrea
authors.initials: A
authors.lastname: Loui
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany. Christoph.Buehrer@charite.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bührer
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany. Jens.Raila@uni-potsdam.de.
authors.forename: Jens
authors.initials: J
authors.lastname: Raila
authors.affiliation: Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany. Florian.Schweigert@uni-potsdam.de.
authors.forename: Florian J
authors.initials: FJ
authors.lastname: Schweigert
mesh_terms: D019587:Dietary Supplements; D005919:Glomerular Filtration Rate; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000652:urine*; D011507:Proteinuria; D012044:Regression Analysis; D012177:Retinol-Binding Proteins / Q000652:urine*; D014801:Vitamin A / Q000008:administration & dosage* / Q000652:urine; D014815:Vitamins / Q000008:administration & dosage* / Q000652:urine
chemical_list: D012177:Retinol-Binding Proteins; D014815:Vitamins; D014801:Vitamin A
keywords: RBP4; Urine excretion; Very low birth weight infant; Vitamin A supplementation