@article{SchmiedchenLongardtLouietal.2016,
  author    = {Schmiedchen, Bettina and Longardt, Ann Carolin and Loui, Andrea and Buehrer, Christoph and Raila, Jens and Schweigert, Florian J.},
  title     = {Effect of vitamin A supplementation on the urinary retinol excretion in very low birth weight infants},
  series = {European journal of pediatrics : official organ of the Belgian Pediatric Association},
  volume    = {175},
  journal   = {European journal of pediatrics : official organ of the Belgian Pediatric Association},
  publisher = {Springer},
  address   = {New York},
  issn      = {0340-6199},
  doi       = {10.1007/s00431-015-2647-9},
  pages     = {365 -- 372},
  year      = {2016},
  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). Conclusion: 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.},
  language  = {en}
}
@article{SchmiedchenLongardtBuehreretal.2014,
  author    = {Schmiedchen, Bettina and Longardt, Ann Carolin and Buehrer, Christoph and Raila, Jens and Loui, Andrea and Schweigert, Florian J.},
  title     = {The relative dose response test based on retinol-binding protein 4 is not suitable to assess vitamin A status in very low birth weight infants},
  series = {Neonatology : fetal and neonatal research},
  volume    = {105},
  journal   = {Neonatology : fetal and neonatal research},
  number    = {2},
  publisher = {Karger},
  address   = {Basel},
  issn      = {1661-7800},
  doi       = {10.1159/000356773},
  pages     = {155 -- 160},
  year      = {2014},
  language  = {en}
}
@article{LongardtSchmiedchenRailaetal.2014,
  author    = {Longardt, Ann Carolin and Schmiedchen, B. and Raila, Jens and Schweigert, Florian J. and Obladen, M. and Buehrer, Christoph and Loui, A.},
  title     = {Characterization of the vitamin A transport in preterm infants after repeated high-dose vitamin A injections},
  series = {European journal of clinical nutrition},
  volume    = {68},
  journal   = {European journal of clinical nutrition},
  number    = {12},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {0954-3007},
  doi       = {10.1038/ejcn.2014.202},
  pages     = {1300 -- 1304},
  year      = {2014},
  abstract  = {BACKGROUND/OBJECTIVES: 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. SUBJECTS/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 41 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.},
  language  = {en}
}