title: Controlled comparison of L-5-methyltetrahydrofolate versus folic acid for the treatment of hyperhomocysteinemia in hemodialysis patients.
abstract: BACKGROUND
  The hyperhomocysteinemia regularly found in hemodialysis patients is largely refractory to combined oral B-vitamin supplementation featuring supraphysiological doses of folic acid. We evaluated whether a high-dose L-5-methyltetrahydrofolate-based regimen provided improved total homocysteine (tHcy)-lowering efficacy in chronic hemodialysis patients.
  
  
  RESULTS
  We block-randomized 50 chronic, stable hemodialysis patients on the basis of their screening predialysis tHcy levels, sex, and dialysis center into 2 groups of 25 subjects treated for 12 weeks with oral folic acid at 15 mg/d (FA group) or an equimolar amount (17 mg/d) of oral L-5-methyltetrahydrofolate (MTHF group). All 50 subjects also received 50 mg/d of oral vitamin B(6) and 1.0 mg/d of oral vitamin B(12). The mean percent reductions (+/-95% CIs) in predialysis tHcy were not significantly different: MTHF, 17.0% (12.0% to 22.0%); FA, 14.8% (9.6% to 20.1%); P=0.444 by matched ANCOVA adjusted for pretreatment tHcy. Final on-treatment values (mean with 95% CI) were MTHF, 20.0 micromol/L (18.8 to 21.2 micromol/L); FA, 19.5 micromol/L (18.3 to 20.7 micromol/L). Moreover, neither treatment resulted in "normalization" of tHcy levels (ie, final on-treatment values <12 micromol/L) among a significantly different or clinically meaningful number of patients: MTHF, 2 of 25 (8%); FA, 0 of 25 (0%); Fisher's exact test of between-groups difference, P=0.490.
  
  
  CONCLUSIONS
  Relative to high-dose folic acid, high-dose oral L-5-methyltetrahydrofolate-based supplementation does not afford improved tHcy-lowering efficacy in hemodialysis patients. The preponderance of hemodialysis patients (ie, >90%) exhibit mild hyperhomocysteinemia refractory to treatment with either regimen. This treatment refractoriness is not related to defects in folate absorption or circulating plasma and tissue distribution.
authors.affiliation: Division of General Internal Medicine, Memorial Hospital of Rhode Island, Pawtucket 02860, USA. abostom@loa.com
authors.forename: A G
authors.initials: AG
authors.lastname: Bostom
authors.forename: D
authors.initials: D
authors.lastname: Shemin
authors.forename: P
authors.initials: P
authors.lastname: Bagley
authors.forename: Z A
authors.initials: ZA
authors.lastname: Massy
authors.forename: A
authors.initials: A
authors.lastname: Zanabli
authors.forename: K
authors.initials: K
authors.lastname: Christopher
authors.forename: P
authors.initials: P
authors.lastname: Spiegel
authors.forename: P F
authors.initials: PF
authors.lastname: Jacques
authors.forename: L
authors.initials: L
authors.lastname: Dworkin
authors.forename: J
authors.initials: J
authors.lastname: Selhub
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004305:Dose-Response Relationship, Drug; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000188:drug therapy* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000009:adverse effects*; D013763:Tetrahydrofolates / Q000008:administration & dosage / Q000627:therapeutic use*; D017211:Treatment Failure
chemical_list: D013763:Tetrahydrofolates; D006710:Homocysteine; D005492:Folic Acid; C005984:5-methyltetrahydrofolate