title: Response of homocysteine, cystathionine, and methylmalonic acid to vitamin treatment in dialysis patients.
abstract: BACKGROUND
  Hyperhomocysteinemia is observed in >80% of hemodialysis patients and is considered a risk factor for cardiovascular disease. Vitamin treatment lowers total homocysteine (tHcy) concentrations in plasma and may therefore reduce the associated risk. Current treatment strategies have not achieved normalization of tHcy in the majority of dialysis patients.
  
  
  METHODS
  We administered folic acid (5 mg) plus vitamin B(6) (50 mg) and B(12) (0.7 mg) intravenously to 38 hyperhomocysteinemic patients (tHcy >18 micromol/L) after each dialysis treatment. The treatment phase lasted 1 month, and serum concentrations of tHcy, methylmalonic acid (MMA), and cystathionine were measured at weeks 0, 2, 4, 6, 8, and 24.
  
  
  RESULTS
  The median serum tHcy concentration decreased significantly, from 26.1 micromol/L at baseline to 13.2 micromol/L at week 4. The median change in tHcy after 4 weeks was 13.4 micromol/L (-51%) compared with baseline. Serum MMA and cystathionine concentrations were reduced by 28% and 26%, respectively, but neither was normalized at 4 weeks. Backward-elimination stepwise regression analysis revealed that higher concentrations of tHcy, MMA, and cystathionine and lower folate at baseline predict changes of tHcy after treatment. Twenty weeks after vitamin withdrawal, tHcy concentrations returned to values comparable to baseline (median, 24.8 micromol/L).
  
  
  CONCLUSIONS
  The combination of folic acid, vitamin B(12), and vitamin B(6) used in this study normalized serum concentrations of tHcy in almost all of our hyperhomocysteinemic dialysis patients. This regimen may be used to investigate the effects of homocysteine normalization on cardiovascular outcomes in hemodialysis patients.
authors.affiliation: Department of Clinical Chemistry, Central Laboratory, Saarland University Hospital, 66421 Homburg, Germany.
authors.forename: Rima
authors.initials: R
authors.lastname: Obeid
authors.forename: Martin K
authors.initials: MK
authors.lastname: Kuhlmann
authors.forename: Hans
authors.initials: H
authors.lastname: Köhler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herrmann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003540:Cystathionine / Q000097:blood*; D004359:Drug Therapy, Combination; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood*; D008875:Middle Aged; D006435:Renal Dialysis; D014805:Vitamin B 12 / Q000627:therapeutic use*; D025101:Vitamin B 6 / Q000627:therapeutic use*
chemical_list: D006710:Homocysteine; D003540:Cystathionine; D025101:Vitamin B 6; D008764:Methylmalonic Acid; D005492:Folic Acid; D014805:Vitamin B 12