Homocysteine status in hemodialysis patients receiving folic acid supplements in Imam Hossein hospital in Tehran

Hyperhomocysteinemia is an independent risk factor for cardiovascular disease (CVD) and especially atherosclerosis. Frequency of hyperhomocysteinemia in hemodialysis patients is higher than the general population. Thus near to 50 percent of the patients die due to CVD. The objective of this study is to determine the frequency of hyperhomocysteinemia in hemodialysis patients receiving 5 mg/d oral folic acid supplements in Imam Hossein hospital in Tehran. In this cross-sectional study, plasma total homocysteine (tHcy) and serum folic acid and vitamin B12 were measured in 40 hemodialysis patients receiving 5 mg/d folic acid supplements from at least three months before. Correlation between these three factors and their correlation with other confounders were determined using non-parametric tests. Dietary intake of B vitamins related to tHcy metabolism, were assessed using 24 hour recall method for 3 consecutive days. Median (median ± IQR) of plasma tHcy and serum folic acid and vitamin B12 were 20.95 ±12.17 µmol/l, 101.55 ± 113.92 ng/ml, 945 ± 526.5 pg/ml relatively. 75% of patients had high values for tHcy, 15% borderline values and only 10% normal values. Respectively,12.5% and 37.5% were in normal range of serum folic acid and vitamin B12 and 87.5 % and 62.5% had abovenormal levels. There was a significant, negative correlation between plasma tHcy and height, serum folic acid and dietary intake of vitamins B6 and B2. Mean tHcy levels were higher in women than in men. The correlation between plasma tHcy and other factors, like age, dialysis duration, dialysis efficiency, cigarette smoking, tea and coffee consumption, menopausal status, diagnosed diabetes mellitus, hypertension and hyperlipidemia, albumin, creatinin, urea and dietary intake of folic acid and vitamin B12 was not significant. Despite supplementation with folic acid, only a small proportion of patients reached normal levels of homocysteine. This, shows the necessity of supplementation with higher doses of folic acid combined with other B-vitamins like B12 and B6. Elevated serum level of folic acid is probably due to the effect of uremic environment on intracellular availability of folic acid. High level of serum B12 is the result of it's restricted conversion to the active form, in the most important conversion site, the kidneys.