title: Intravenous administration of vitamin B12 in the treatment of hyperhomocysteinemia associated with end-stage renal disease.
abstract: BACKGROUND
  High serum levels of total homocysteine (tHcy) are common in dialysis patients with end-stage renal disease (ESRD). We assumed that these patients may have decreased response to conventional folic acid (FOL) and vitamin B12 (B12) administered orally. This study aimed to evaluate the efficacy of an intravenous (i.v.) B12 regimen in ESRD patients and compare it with the conventional regimen.
  
  
  METHODS
  We designed an open label, crossover, non-randomized study of 72 ESRD patients. Our patients were hemodialyzed in two hospitals (HOSP1 and HOSP2). In HOSP1, patients were on 1 mg of FOL and 600 micog of B12 orally for 3 months, and then switching to 1 mg of B12 i.v. for 3 additional months, while the FOL dosage was constant. In HOSP2, patients received the same treatment in reverse.
  
  
  RESULTS
  Patients in HOSP1 (n = 37) after i.v. B12 treatment, had significantly lower tHcy (p < 0.001) and FOL (p < 0.05) serum levels, compared with those at the end of oral B12 treatment. On the contrary in HOSP2 patients, serum tHcy levels increased significantly (n = 35, p < 0.0001) when i.v. was switched to oral treatment. There was a significant inverse correlation between tHcy and B12 (p < 0.0001) at the end of the i.v. treatment period; while treatment there was no correlation between tHcy and FOL serum levels. At the end of the oral treatment period, there was no significant correlation between tHcy and B12 serum levels, while tHcy and FOL serum levels had a significant inverse correlation (p = 0.002).
  
  
  CONCLUSIONS
  Our results suggest that ESRD patients on dialysis have 'B12 resistance', and that they should have, in addition to their FOL therapeutic regimen, i.v. B12 treatment to reduce their elevated tHcy levels.
authors.affiliation: Department of Internal Medicine, University Hospital of Crete, Crete, Greece.
authors.forename: George E
authors.initials: GE
authors.lastname: Vrentzos
authors.forename: John A
authors.initials: JA
authors.lastname: Papadakis
authors.forename: Konstantinos E
authors.initials: KE
authors.lastname: Vardakis
authors.forename: Niki
authors.initials: N
authors.lastname: Maliaraki
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Stilianou
authors.forename: Antonios
authors.initials: A
authors.lastname: Arvanitis
authors.forename: Spiridon
authors.initials: S
authors.lastname: Sratigis
authors.forename: Polychronis
authors.initials: P
authors.lastname: Alivanis
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Margioris
authors.forename: Emmanuel S
authors.initials: ES
authors.lastname: Ganotakis
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage; D005500:Follow-Up Studies; D006801:Humans; D020138:Hyperhomocysteinemia / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology*; D007262:Infusions, Intravenous; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011336:Probability; D012016:Reference Values; D006435:Renal Dialysis / Q000009:adverse effects* / Q000379:methods; D018570:Risk Assessment; D012720:Severity of Illness Index; D016037:Single-Blind Method; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014805:Vitamin B 12 / Q000008:administration & dosage*
chemical_list: D005492:Folic Acid; D014805:Vitamin B 12