Objective: The authors found considerably lower plasma total homocysteine (tHcy) concentrations in patients with end-stage renal disease (ESRD) on maintenance hemodialysis, who routinely received high-dose parenteral vitamin B12, than in comparable patients receiving much higher doses of folic acid but only replacement-dose oral vitamin B12. They therefore sought prospective evidence that high-dose parenterally administered vitamin B12 may partially ameliorate renal failure-associated hyperhomocysteinemia.
Design: Open phase 2 clinical trial.
Setting: Outpatient hemodialysis unit.
Patients: Fourteen clinically stable patients on maintenance hemodialysis with normal baseline serum vitamin B12 concentrations.
Intervention: Three parenteral injections of 1 mg vitamin B12 given at 4-week intervals.
Outcome measures: Plasma tHcy and serum vitamin B12 concentrations were measured before, during and 7 months after the termination of vitamin B12 therapy.
Results: The mean (and standard error) baseline plasma tHcy was 26.5 (1.8) micromol/L. The plasma tHcy value fell successively after each vitamin injection to reach a value of 23.6 (1.6) micromol/L 1 month after the final injection (p < 0.05), while the serum vitamin B12 concentration increased from 471 (42) pmol/L to 890 (74) pmol/L (p < 0.05). Seven months after the final injection, the serum B12 concentration had fallen and tHcy had risen to near their original values.
Conclusions: Three monthly vitamin B12 injections modestly but distinctly reduced tHcy concentrations in hemodialysis patients whose prior vitamin B12 status was normal. Randomized placebo-controlled clinical trials of longer duration and using larger or more frequent parenteral doses are indicated to determine whether administration of this safe and inexpensive vitamin can improve hyperhomocysteinemia in ESRD.