Reduction of the homocysteine plasma concentration by intravenously administered folinic acid and vitamin B-12 in uraemic patients on maintenance haemodialysis

Background. Hyperhomocysteinaemia is an independent cardiovascular risk fac tor which can induce vascular lesions, thus contributing to the early devel opment of atherosclerosis. Low-dose folic acid supplementation reduces the pretreatment homocysteine plasma levels by 25-35%. Recent studies report th at higher intravenous or oral administration of the active form of folic ac id reduces the homocysteine plasma concentration by nearly 70%. The reducti on could also be influenced by the thermolabile variant of methylenetetrahy drofolate reductase (tMTHFR) and by the dialysis modality. Methods: A cross -sectional clinical study was performed to evaluate the effect of a drug co ntaining folinic acid and vitamin B-12 on the plasma homocysteine concentra tion and whether this variable could also be influenced by the presence of a genetic variant of the methionine pathway and the use of different dialys is modalities. The plasma homocysteine concentration was measured in 55 pat ients undergoing haemodialysis, 27 of whom have been treated intravenously for megaloblastic anaemia using a drug containing low concentrations of fol inic acid and vitamin B12 at the end of each dialysis session for 6 months. The presence of tMTHFR was sought by molecular analysis, and the role of t he dialysis modality was also investigated. Results. The patients given the folic acid treatment had lower homocysteine plasma levels than those not s o treated. The plasma homocysteine concentration was significantly higher i n the tMRHFR homozygotes than in the patients with a normal genotype, signi ficantly lower in the treated than in the untreated homozygotes, and signif icantly higher in the untreated homozygotes than in the untreated subgroup with a normal genotype. The homocysteine level was also significantly lower in the patients who underwent convective haemodialysis than in those who r eceived standard bicarbonate dialysis. Conclusions: A drug containing low c oncentrations of folinic acid combined with vitamin B-12 using an intermitt ent intravenous regimen is effective in reducing the homocysteine plasma co ncentration in uraemic patients. The homocysteine levels seem also to depen d on genotype and dialysis modality. Copyright (C) 2001 S.Karger AG, Basel.