title: Oral vitamin C supplementation reduces erythropoietin requirement in hemodialysis patients with functional iron deficiency.
abstract: OBJECTIVE
  Functional iron deficiency (FID) is a major cause of persistent anemia in dialysis patients and also contributes to a suboptimal response to erythropoietin (Epo) administration. Vitamin C acts as an enzyme cofactor and enhances mobilization of the ferrous form of iron to transferrin thus increasing its bioavailability. High-dose intravenous vitamin C has been shown to decrease the Epo requirement and improve hemoglobin levels in previous studies. This study assessed the effect of low-dose oral vitamin C on possible reduction in Epo dose requirements in stable hemodialysis patients with FID.
  
  
  METHODS
  This prospective study included 22 stable hemodialysis patients with FID defined as transferrin saturation (T sat) <30 % and ferritin levels of >100 mcg/L with Epo requirement of ≥4000 U/HD session. Patients received oral vitamin C 250 mg daily for 3 months. Hemoglobin, iron and T sat levels were recorded monthly. No one received iron supplementation during the study period.
  
  
  RESULTS
  There was a significant reduction in median Epo dose requirement in the 15 patients who completed the study, from 203.1 U/kg/week (95 % CI 188.4-270.6) to 172.8 U/kg/week (95 % CI 160.2-214.8), (P = 0.01). In the seven responders, there was 33 % reduction in Epo dose from their baseline. Despite adjustment of Epo dose, the mean hemoglobin level was significantly increased from 10.1 ± 0.6 to 10.7 ± 0.6 mg/dL (P = 0.03). No adverse effects of oral vitamin C were observed.
  
  
  CONCLUSIONS
  Daily low-dose oral vitamin C supplementation reduced Epo dose requirements in hemodialysis patients with FID. Limitations of this study include a small sample size and the lack of measurements of vitamin C and oxalate levels. Despite concerns regarding oral vitamin C absorption in dialysis patients, this study indicates vitamin C was well tolerated by all participants without reported adverse effect.
authors.affiliation: Division of Nephrology, Lenox Hill Hospital, New York, NY, USA. drtanjimsultana@yahoo.com.
authors.forename: Tanjim
authors.initials: T
authors.lastname: Sultana
authors.affiliation: Division of Nephrology, Lenox Hill Hospital, New York, NY, USA.
authors.forename: Maria V
authors.initials: MV
authors.lastname: DeVita
authors.affiliation: Division of Nephrology, Lenox Hill Hospital, New York, NY, USA.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Michelis
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001205:Ascorbic Acid / Q000008:administration & dosage*; D019587:Dietary Supplements; D004920:Erythropoiesis / Q000187:drug effects; D004921:Erythropoietin / Q000008:administration & dosage*; D005260:Female; D005293:Ferritins / Q000097:blood; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000097:blood*; D000090463:Iron Deficiencies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects; D051436:Renal Insufficiency, Chronic / Q000628:therapy*; D014168:Transferrin / Q000378:metabolism; D014815:Vitamins / Q000008:administration & dosage*
chemical_list: D006454:Hemoglobins; D014168:Transferrin; D014815:Vitamins; D004921:Erythropoietin; D005293:Ferritins; D007501:Iron; D001205:Ascorbic Acid
keywords: Anemia; Erythropoietin; Functional iron deficiency; Vitamin C