Journal Article

Treatment with different doses of folic acid in haemodialysis patients: effects on folate distribution and aminothiol concentrations

Margret Arnadottir, Vilmundur Gudnason and Björn Hultberg

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 15, issue 4, pages 524-528
Published in print April 2000 | ISSN: 0931-0509
Published online April 2000 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/15.4.524
Treatment with different doses of folic acid in haemodialysis patients: effects on folate distribution and aminothiol concentrations

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Background. Hyperhomocysteinaemia is highly prevalent among haemodialysis patients and may contribute to their increased cardiovascular risk. Treatment with pharmacological doses of folic acid lowers the plasma homocysteine concentration in these patients. The purpose of the present study was to expand the knowledge about such treatment by testing the effects of stepwise increases in the dose of folic acid on the concentrations of plasma and red blood cell folate as well as the total plasma concentrations of homocysteine (tHcy), cysteine (tCys), and glutathione (tGSH) in patients on chronic hemodialysis.

Methods. Fourteen stable haemodialysis patients completed the study which consisted of four consecutive periods, each of 6 weeks duration: (i) no treatment with folic acid (control period); (ii) 5 mg of folic acid three times per week (15 mg/week); (iii) 5 mg of folic acid daily (35 mg/week); (iv) 10 mg of folic acid daily (70 mg/week).

Results. Neither plasma or red cell folate nor plasma aminothiol concentrations changed significantly during the control period. The mean red cell folate concentration doubled during the administration of folic acid at the dose of 15 mg/week but at higher doses the further rise was only marginal. The mean folate concentration in plasma increased steeply especially at the higher doses of folic acid. During treatment with 15 mg/week of folic acid, tHcy fell by a mean of 36%, tGSH increased by a mean of 34%, but tCys was unaffected. Increases in the dose of folic acid did not augment these responses.

Conclusions. The maximal effect on tHcy seemed to be obtained already at the lowest given dose of folic acid (15 mg/week). At that dose, the red blood cells approached folate saturation, which may reflect the situation in other cells that participate in homocysteine metabolism and explain why further increases in the dose of folic acid are not effective from a tHcy-lowering point of view.

Keywords: cysteine; folate; glutathione; haemodialysis; homocysteine; renal failure

Journal Article.  3464 words.  Illustrated.

Subjects: Nephrology

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