Intravenous administration of vitamin B12 in the treatment of hyperhomocysteinemia associated with end-stage renal disease.

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.