title: Hypervitaminosis A is prevalent in children with CKD and contributes to hypercalcemia.
abstract: BACKGROUND
  Vitamin A accumulates in renal failure, but the prevalence of hypervitaminosis A in children with predialysis chronic kidney disease (CKD) is not known. Hypervitaminosis A has been associated with hypercalcemia. In this study we compared dietary vitamin A intake with serum retinoid levels and their associations with hypercalcemia.
  
  
  METHODS
  We studied the relationship between vitamin A intake, serum retinoid levels, and serum calcium in 105 children with CKD stages 2-5 on dialysis and posttransplant. Serum retinoid measures included retinol (ROH), its active retinoic acid (RA) metabolites [all-trans RA (at-RA) and 13-cis RA] and carrier proteins [retinol-binding protein-4 (RBP4) and transthyretin (TTR)]. Dietary vitamin A intake was assessed using a food diary.
  
  
  RESULTS
  Twenty-five children were in CKD 2-3, 35 in CKD 4-5, 23 on dialysis and 22 posttransplant; 53 % had vitamin A intake above the Reference Nutrient Intake (RNI) value. Children receiving supplemental feeds compared with diet alone had higher vitamin A intake (p = 0.02) and higher serum ROH (p < 0.001). Notably, increased ROH was seen as early as CKD stage 2. For every 10 ml/min/1.73 m(2) fall in estimated glomerular filtration rate (eGFR), there was a 13 % increase in ROH. RBP4 levels were increased in CKD 3-5 and dialysis patients. The lowest ratios of ROH:RBP4 were seen in dialysis compared with CKD 2-3 (p = 0.03), suggesting a relative increase in circulating RBP4. Serum ROH, RBP4 and at-RA were associated with serum calcium. On multivariable analysis RBP4 levels and alfacalcidol dose were significant predictors of serum calcium (model R (2) 32 %) in dialysis patients.
  
  
  CONCLUSIONS
  Hypervitaminosis A is seen in early CKD, with highest levels in children on supplemental feeds compared with diet alone. Serum retinoid levels significantly predict hypercalcemia.
authors.affiliation: Department of Dietetics, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom.
authors.forename: Baheerathi
authors.initials: B
authors.lastname: Manickavasagar
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: McArdle
authors.forename: Pallavi
authors.initials: P
authors.lastname: Yadav
authors.forename: Vanessa
authors.initials: V
authors.lastname: Shaw
authors.forename: Marjorie
authors.initials: M
authors.lastname: Dixon
authors.forename: Rune
authors.initials: R
authors.lastname: Blomhoff
authors.forename: Graeme O'
authors.initials: GO
authors.lastname: Connor
authors.forename: Lesley
authors.initials: L
authors.lastname: Rees
authors.forename: Sarah
authors.initials: S
authors.lastname: Ledermann
authors.forename: William
authors.initials: W
authors.lastname: Van't Hoff
authors.forename: Rukshana
authors.initials: R
authors.lastname: Shroff
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000209:etiology*; D006986:Hypervitaminosis A / Q000150:complications*; D007223:Infant; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications*