title: Vitamin A deficiency associated with urinary retinol binding protein wasting in Dent's disease.
abstract: BACKGROUND
  Three patients with Dent's disease presented with complaints of impaired night vision or xerophthalmia and were found to have severely decreased serum retinol concentrations. Retinol, bound to its carrier retinol-binding protein (RBP), is filtered at the glomerulus and reabsorbed at the proximal tubule. We hypothesized that urinary loss of retinol-RBP complex is responsible for decreased serum retinol.
  
  
  OBJECTIVE
  The study aim was to investigate vitamin A status and RBP in serum and urine of patients with genetically confirmed Dent's disease.
  
  
  RESULTS
  Eight patients were studied, three boys had clinical vitamin A deficiency, three had asymptomatic deficiency, and two young men with Dent's disease and impaired renal function had normal retinol values. Serum RBP concentrations were low in patients with vitamin A deficiency and were correlated with vitamin A levels. Urinary RBP concentrations were increased in all patients (2,000-fold), regardless of vitamin A status. This was in contrast to patients with glomerular proteinuria who had only mildly increased urinary RBP with normal serum RBP and vitamin A, and patients with cystinosis with impaired renal function who had massive urinary RBP losses but without a decrease in serum RBP or vitamin A levels. Treatment with vitamin A supplements in patients with retinol deficiency resulted in rapid resolution of ocular symptoms and an increase in serum retinol concentrations.
  
  
  CONCLUSIONS
  Vitamin A deficiency is common in patients with Dent's disease and preserved renal function. We therefore recommend screening these patients for retinol deficiency and treating them before visual symptoms develop.
authors.affiliation: Division of Pediatric Nephrology, Shaare Zedek Medical Center, POB 3235, Jerusalem, 93031, Israel. rbeckercohen@yahoo.com
authors.forename: Rachel
authors.initials: R
authors.lastname: Becker-Cohen
authors.forename: Choni
authors.initials: C
authors.lastname: Rinat
authors.forename: Efrat
authors.initials: E
authors.lastname: Ben-Shalom
authors.forename: Sofia
authors.initials: S
authors.lastname: Feinstein
authors.forename: Heftziba
authors.initials: H
authors.lastname: Ivgi
authors.forename: Yaacov
authors.initials: Y
authors.lastname: Frishberg
mesh_terms: D002648:Child; D002675:Child, Preschool; D018118:Chloride Channels / Q000235:genetics; D004252:DNA Mutational Analysis; D057973:Dent Disease / Q000150:complications* / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D008297:Male; D009154:Mutation; D009755:Night Blindness / Q000209:etiology; D012177:Retinol-Binding Proteins / Q000652:urine*; D014801:Vitamin A / Q000627:therapeutic use / Q000652:urine; D014802:Vitamin A Deficiency / Q000209:etiology* / Q000378:metabolism* / Q000503:physiopathology; D014815:Vitamins / Q000627:therapeutic use
chemical_list: C097503:CLC-5 chloride channel; D018118:Chloride Channels; D012177:Retinol-Binding Proteins; D014815:Vitamins; D014801:Vitamin A