Difference in the homocysteine-lowering effect of folic acid in haemodialysis patients with and without occlusive vascular disease

Background. Hyperhomocysteinaemia has been identified as an independent car diovascular risk factor and is found in more than 85% of patients on mainte nance haemodialysis. Previous studies have shown that folic acid can lower circulating homocysteine in dialysis patients. We evaluated prospectively t he effect of increasing the folic acid dosage from 1 to 6 mg per dialysis o n plasma total homocysteine levels of haemodialysis patients with and witho ut a history of occlusive vascular artery disease (OVD). Methods. Thirty-nine stable patients on high-flux dialysis were studied. Th eir mean age was 63 +/- 11 years and 17 (43%) had a history of OVD, either coronary and/or cerebral and/or peripheral occlusive disease. For several y ears prior to the study, the patients had received an oral post-dialysis mu ltivitamin supplement including 1 mg of folic acid per dialysis. After base line determinations, the folic acid dose was increased from 1 to 6 mg/dialy sis for 3 months. Results. After 3 months, plasma homocysteine had decreased significantly by approximate to 23% from 31.1 +/- 12.7 to 24.5 +/- 9 mu mol/l (P = 0.0005), while folic acid concentrations had increased from 6.5 +/- 2.5 to 14.4 +/- 2.5 mug/l (P < 0.0001). However, the decrease of homocysteine was quite di fferent in patients with and in those without OVD. In patients with OVD, ho mocysteine decreased only marginally by <approximate to>2.5% (from 29.0 +/- 10.3 to 28.3 +/- 8.4 mu mol/l, P = 0.74), whereas in patients without OVD there was a significant reduction of approximate to 34% (from 32.7 +/- 14.4 to 21.6 +/- 8.6 mu mol/l, P = 0.0008). Plasma homocysteine levels were red uced by >15% in three patients (18%) in the group with OVD compared with 19 (86%) in the group without OVD (P = 0.001), and by > 30% in none of the pa tients (0%) in the former group compared with 13 (59%) in the latter (P = 0 .001). Conclusions. These results indicate that the homocysteine-lowering effect o f folic acid administration appears to be less effective in haemodialysis p atients having occlusive vascular disease than in those without evidence of such disease.