Jutta Dierkes

DACH-LIGA Homocystein (German, Austrian and Swiss Homocysteine Society): Consensus Paper on the Rational Clinical Use of Homocysteine, Folic Acid and B-Vitamins in Cardiovascular and Thrombotic Diseases: Guidelines and Recommendations

Abstract About half of all deaths are due to cardiovascular disease and its complications. The economic burden on society and the healthcare system from cardiovascular disability, complications, and treatments is huge and getting larger in the rapidly aging populations of developed countries. As conventional risk factors fail to account for part of the cases, homocysteine, a “new” risk factor, is being viewed with mounting interest. Homocysteine is a sulfur-containing intermediate product in the normal metabolism of methionine, an essential amino acid. Folic acid, vitamin B12, and vitamin B6 deficiencies and reduced enzyme activities inhibit the breakdown of homocysteine, thus increasing the intracellular homocysteine concentration. Numerous retrospective and prospective studies have consistently found an independent relationship between mild hyperhomocysteinemia and cardiovascular disease or all-cause mortality. Starting at a plasma homocysteine concentration of approximately 10 μmol/l, the risk increase follows a linear dose-response relationship with no specific threshold level. Hyperhomocysteinemia as an independent risk factor for cardiovascular disease is thought to be responsible for about 10% of total risk. Elevated plasma homocysteine levels (>12 μmol/l; moderate hyperhomocysteinemia) are considered cytotoxic and are found in 5 to 10% of the general population and in up to 40% of patients with vascular disease. Additional risk factors (smoking, arterial hypertension, diabetes, and hyperlipidemia) may additively or, by interacting with homocysteine, synergistically (and hence over-proportionally) increase overall risk. Hyperhomocysteinemia is associated with alterations in vascular morphology, loss of endothelial anti-thrombotic function, and induction of a procoagulant environment. Most known forms of damage or injury are due to homocysteinemediated oxidative stress. Especially when acting as direct or indirect antagonists of cofactors and enzyme activities, numerous agents, drugs, diseases, and lifestyle factors have an impact on homocysteine metabolism. Folic acid deficiency is considered the most common cause of hyperhomocysteinemia. An adequate intake of at least 400 μg of folate per day is difficult to maintain even with a balanced diet, and highrisk groups often find it impossible to meet these folate requirements. Based on the available evidence, there is an increasing call for the diagnosis and treatment of elevated homocysteine levels in high-risk individuals in general and patients with manifest vascular disease in particular. Subjects of both populations should first have a baseline homocysteine assay. Except where manifestations are already present, intervention, if any, should be guided by the severity of hyperhomocysteinemia. Consistent with other working parties and consensus groups, we recommend a target plasma homocysteine level of <10 μmol/l. Based on various calculation models, reduction of elevated plasma homocysteine concentrations may theoretically prevent up to 25% of cardiovascular events. Supplementation is inexpensive, potentially effective, and devoid of adverse effects and, therefore, has an exceptionally favorable benefit/risk ratio. The results of ongoing randomized controlled intervention trials must be available before screening for, and treatment of, hyperhomocysteinemia can be recommended for the apparently healthy general population.

Cardiac troponin T predicts mortality in patients with end-stage renal disease

BackgroundPatients with end-stage renal disease have a high risk of premature death, mainly as the result of cardiovascular disease (CVD), which is not sufficiently explained by the conventional risk factors. We therefore prospectively investigated total mortality and cardiovascular events in 102 patients on hemodialysis and assessed the prognostic value of baseline disease status and laboratory variables including total homocysteine and cardiac troponin T. Methods and ResultsPatients were followed for 2 years or until their first event of CVD (for outcome variable cardiovascular events, n=33) or death (for outcome variable total mortality, n=28). Survival was computed by the Kaplan-Meier method. Cox proportional hazards model was used to determine independent predictors of CVD events or total mortality. Cardiac troponin T emerged as the most powerful predictor of mortality, resulting in an almost 7-fold risk increase at concentrations >0.10 ng/mL (hazard ratio 6.85, 95% CI 3.04 to 15.45). Total homocysteine level greater than median was also associated with mortality (hazard ratio 2.44, 95% CI 1.10 to 5.40). These hazard ratios did not change substantially after adjustment for other risk factors. Significant predictors for CVD events were baseline diabetes, cerebrovascular disease, serum glucose, and triglycerides. After adjustment, only glucose and triglycerides remained significantly related to CVD events (hazard ratio with 95% CI 1.33 [1.12 to 1.57] and 1.14 [1.04 to 1.26], respectively, for a 1-mmol/L increase in concentration). ConclusionsWe conclude that total homocysteine and particularly cardiac troponin T are important predictors of mortality in patients with end-stage renal disease, whereas other laboratory variables and baseline disease status have less prognostic value.

B Vitamins and the Risk of Total Mortality and Cardiovascular Disease in End-Stage Renal Disease Results of a Randomized Controlled Trial

Background— In observational studies, hyperhomocysteinemia has been found to be a risk factor for total mortality and cardiovascular events in patients with end-stage renal disease. These patients have grossly elevated homocysteine levels that can be lowered by supplementation with folic acid and vitamin B12. We conducted a randomized clinical trial with B vitamins to reduce homocysteine levels and therefore cardiovascular events and total mortality. Methods and Results— This randomized, double-blind multicenter study was conducted in 33 dialysis centers in north and east Germany between July 2002 and July 2008. We randomly assigned 650 patients with end-stage renal disease who were undergoing hemodialysis to 2 postdialysis treatments: 5 mg folic acid, 50 &mgr;g vitamin B12, and 20 mg vitamin B6 (active treatment) or 0.2 mg folic acid, 4 &mgr;g vitamin B12, and 1.0 mg vitamin B6 (placebo) given 3 times per week for an average of 2 years. The primary outcome was total mortality; the secondary outcome was fatal and nonfatal cardiovascular events. The primary outcome occurred in 102 patients (31%) receiving the active treatment and in 92 (28%) receiving placebo (hazard ratio, 1.13; 95% confidence interval, 0.85 to 1.50; P=0.51). The secondary outcome occurred in 83 patients (25%) receiving the active treatment and in 98 (30%) receiving placebo (hazard ratio, 0.80; 95% confidence interval, 0.60 to 1.07; P=0.13). Conclusions— Increased intake of folic acid, vitamin B12, and vitamin B6 did not reduce total mortality and had no significant effect on the risk of cardiovascular events in patients with end-stage renal disease. Clinical Trial Registration— URL: www.anzctr.org.au. Unique identifier: ACTRN12609000911291. URL: www.cochrane-renal.org. Unique identifier: CRG010600027.

Detection of Recent Ethanol Intake With New Markers: Comparison of Fatty Acid Ethyl Esters in Serum and of Ethyl Glucuronide and the Ratio of 5-Hydroxytryptophol to 5-Hydroxyindole Acetic Acid in Urine

BACKGROUND At present, recent ethanol consumption can be routinely detected with certainty only by direct measurement of ethanol concentration in blood or urine. Because ethanol is rapidly eliminated from the circulation, however, the time span for this detection is in the range of hours. Several new markers have been proposed to extend the detection interval, but their characteristics have not yet justified their use in routine clinical practice. We therefore investigated three new markers and compared their kinetics and sensitivities: (1) fatty acid ethyl esters (FAEEs) in serum, (2) ethyl glucuronide (EtG) in urine, and (3) the ratio of 5-hydroxytryptophol to 5-hydroxyindole acetic acid (5-HTOL/5-HIAA) in urine. METHODS Seventeen healthy men participated in a drinking experiment. Blood and urine samples were collected twice daily on three consecutive days and once daily on days 4 and 5. Ethanol concentration was determined by gas chromatography, FAEE levels, by gas chromatography with mass spectrometry, EtG concentration, by liquid chromatography-tandem mass spectrometry, and 5-HTOL/5-HIAA ratio, by high-performance liquid chromatography. RESULTS The peak serum ethanol concentrations of the subjects ranged from 5.4 to 44.7 mmol/liter (mean +/- SD, 30.1 +/- 9.1 mmol/liter). In the case of the serum ethanol determination, 100% sensitivity was reached only immediately after the end of the drinking experiment, and in the case of FAEE levels and 5-HTOL/5-HIAA ratio, it tested for 6.7 hr after the end of the ethanol intake. Thereafter, these latter parameters declined until 15.3 hr (FAEEs) and 29.4 hr (5-HTOL/5-HIAA), subsequently remaining in a stable range until 78.5 hr without further decrease. In contrast, EtG concentration showed 100% sensitivity until 39.3 hr and thereafter decreased, falling to below the limit of quantification of 0.1 mg/liter at 102.5 hr. CONCLUSION After moderate drinking, EtG in the urine proved to be a superior marker of recent ethanol consumption in healthy subjects. This is because EtG is a direct ethanol metabolite, it occurs in the urine only when ethanol has been consumed, and its sensitivity remains at the level of 100% for 39.3 hr.

The Number of Lymph Node Metastases in Gastric Cancer Correlates with the Angiotensin I–Converting Enzyme Gene Insertion/Deletion Polymorphism

Purpose: In the present study, we aimed to substantiate the putative significance of angiotensin I–converting enzyme (ACE) on gastric cancer biology by investigating the influence of its gene polymorphism on gastric cancer progression. Experimental Design: Genomic DNA was purified from peripheral blood mononuclear cells or tissue specimens. Amplified ACE gene fragments were separated on agarose gels. D or I alleles were identified by the presence of 190- or 490-bp fragments, respectively. Local expression of ACE was investigated by immunohistochemistry. Results: Twenty-four of 113 (21%) gastric cancer patients had the II, 57 (51%) the ID, and 32 (28%) the DD genotype. The distribution of the ACE genotypes did not differ significantly from the control group of 189 patients without gastric cancer. However, the ACE genotypes correlated with the number of lymph node metastases and the Unio Internationale Contra Cancrum (UICC) tumor stage. Patients with the II genotype had a highly significantly smaller number of lymph node metastases (P < 0.001) and a significantly lower UICC tumor stage (P = 0.01) than patients with the DD genotype. No correlation was found between tumor type, tumor location, local tumor growth, distant metastases, and the ACE genotype. The expression of ACE in gastric cancer was investigated by immunohistochemistry in 100 of 113 patients. ACE was expressed by endothelial cells in all (100%) specimens and by tumor cells in 56 (56%) specimens. Conclusions: Our study shows that ACE is expressed locally in gastric cancer and that the gene polymorphism influences metastatic behavior.

Relation between homocysteinaemia and diabetic neuropathy in patients with Type 2 diabetes mellitus

Aims  Limited data are available on determinants of diabetic neuropathy as its pathogenesis is multifactorial. Since homocysteine exhibits toxic effects on vascular endothelial cells, the association between homocysteine and the prevalence of neuropathy in Type 2 diabetes mellitus was investigated.

Homocysteine as a Risk Factor for Cardiovascular Disease in Patients Treated by Dialysis: A Meta–analysis

BACKGROUND In the general population, increased homocysteine concentrations are a risk factor for cardiovascular disease and mortality. However, it is not known whether this also applies to patients with end-stage renal disease. STUDY DESIGN Meta-analysis of retrospective (11 studies including 1,506 individuals), prospective observational studies (12 studies including 1,975 individuals), and intervention trials (5 studies including 1,642 dialysis patients). Analyses were carried out separately, according to the study design. SETTING & POPULATION Studies of patients with end-stage renal disease treated by means of hemodialysis or peritoneal dialysis. SELECTION CRITERIA FOR STUDIES Studies investigating the association between total homocysteine level and cardiovascular disease or total mortality or the influence of vitamin supplementation on cardiovascular or mortality risk. INTERVENTION In intervention studies, vitamin preparations with folic acid alone or in combination with other vitamins, such as vitamin B(12) and B(6), were used. OUTCOMES In retrospective studies, cases are patients with cardiovascular diseases. Outcomes for prospective observational and intervention studies are cardiovascular events and total mortality. RESULTS In retrospective studies, there was no significant overall difference in homocysteine concentrations between cases and controls (weighted mean difference in homocysteine, 2.82 micromol/L; 95% confidence interval [CI], -2.22 to 7.86; P = 0.3). The pooled overall risk estimate for prospective observational studies suggests no association between homocysteine level (5-micromol/L increase) and total mortality (hazard ratio [HR], 1.02; 95% CI, 0.93 to 1.12; P = 0.7), but there was an association with cardiovascular events (HR, 1.09; 95% CI, 1.03 to 1.14; P = 0.001). In subgroup analysis of patients not receiving vitamins, an increase in homocysteine level was associated with increased mortality (HR, 1.07; 95% CI, 1.02 to 1.13; P = 0.01). For intervention trials with B vitamins, there was a significant risk reduction for cardiovascular disease (relative risk, 0.73; 95% CI, 0.56 to 0.94; P = 0.02), but no risk reduction for total mortality or the composite end point including total mortality (relative risk, 1.01; 95% CI, 0.88 to 1.15; P = 0.9). LIMITATIONS Many studies are small, which may lead to the observed heterogeneity. Some intervention trials are neither placebo controlled nor randomized. Separate analyses for specific end points and patients treated by means of hemodialysis or peritoneal dialysis were not possible. CONCLUSION Total homocysteine level may be a risk factor for cardiovascular events and total mortality in patients with end-stage renal disease not receiving vitamin supplementation or folic acid food fortification. There may be a potential for reducing cardiovascular disease in this population by folic acid supplementation.

Supplementation with vitamin B12 decreases homocysteine and methylmalonic acid but also serum folate in patients with end-stage renal disease

Hyperhomocysteinemia is frequently found in patients with end-stage renal disease (ESRD). Plasma total homocysteine (tHcy) concentrations may be reduced by supplementation with folic acid or combinations of folic acid, vitamin B12, and vitamin B6. Supplementation studies with vitamin B12 alone in patients with ESRD have not yet been published. In this study, we investigated the effects of intravenous injection of cyanocobalamin (1 mg/wk for 4 weeks) in ESRD patients (N = 14) with low serum cobalamin concentrations (<180 pmol/L). All patients had elevated levels of plasma tHcy, methylmalonic acid (MMA), and cystathionine before supplementation. After supplementation, plasma tHcy and MMA decreased 35% and 48%, respectively; however, cystathionine levels were unchanged. The extent of the plasma tHcy reduction tended to be influenced by the C677T polymorphism of methylenetetrahydrofolate reductase (MTHFR). Serum cobalamin increased significantly upon supplementation, whereas serum folate levels were substantially reduced by 47%. In contrast, red blood cell (RBC) folate was unchanged. This study shows that vitamin B12 supplementation effectively decreases both MMA and plasma tHcy in ESRD patients with low B12 levels. Furthermore, it illustrates the close interrelation between vitamin B12 and folate metabolism.

The Angiotensin I–Converting Enzyme Gene Insertion/Deletion Polymorphism Is Linked to Early Gastric Cancer

The insertion/deletion polymorphism of the angiotensin I–converting enzyme (ACE) gene has recently been linked to the pathogenesis and progression of human cancers. Using genomic DNA from 88 patients with early gastric cancer confined either to mucosa (pT1a) or submucosa (pT1b), we assessed the insertion (I) and deletion (D) polymorphism by PCR analysis and compared it with a large noncancer control population (n = 145). In the noncancer control group, the II genotype was observed in 33 (23%) individuals, whereas the ID and DD genotypes were found in 72 (50%) and 40 (27%) individuals, respectively. Interestingly, in the cancer group, we found the II genotype in six (7%) patients and the ID genotype in 46 (52%) individuals, whereas the DD genotype was observed in 36 (41%) individuals (P = 0.0034). Accordingly, the odds ratio for the II genotype was 0.20 [95% confidence interval (95% CI), 0.08-0.54; P = 0.009] and 0.55 for the ID/II genotype (95% CI, 0.31-0.96; P = 0.044) using the high-activity genotype DD as the reference category. No correlation was found among tumor type, tumor stage, the presence of Helicobacter pylori, and the ACE genotype. Our study provides further evidence that the ACE insertion/deletion gene polymorphism may be linked to the development of early gastric cancer. (Cancer Epidemiol Biomarkers Prev 2005;14(12):2987–9)

Prevalences of hyperhomocysteinemia, unfavorable cholesterol profile and hypertension in European populations

BackgroundHyperhomocysteinemia (HHCY) is a risk factor for cardiovascular diseases (CVD). HHCY may interact with hypertension (HTEN) and an unfavorable cholesterol profile (UNFAVCHOL) to alter the risk of CVD.ObjectivesTo estimate the prevalences of HHCY (1) isolated and (2) in combination with UNFAVCHOL and/or HTEN in different age categories. To provide information that may improve the screening and treatment of subjects at risk of CVD.DesignCross-sectional data on 12 541 men and 12 948 women aged 20+ y were used from nine European studies.ResultsThe prevalence of isolated HHCY was 8.5% in subjects aged 20–40 y, 4.7% in subjects aged 40–60 y and 5.9% in subjects aged over 60 y. When combining all age groups, 5.3% had isolated HHCY and an additional 5.6% had HHCY in combination with HTEN and/or UNFAVCHOL. The combinations of risk factors increased with age and, except for HHCY&UNFAVCHOL, were more prevalent than predicted by chance. Of the young subjects (20–40 y), 24% suffered from one or more of the investigated CVD risk factors. This figure was 75.1% in the old subjects (60+ years).ConclusionsA substantial number of subjects in selected European populations have HHCY (10.9%). In half of these cases, subjects suffer also from other CVD risk factors like UNFAVCHOL and HTEN. Older people in particular tend to have more than one risk factor. Healthcare professionals should be aware of this when screening and treating older people not only for the conventional CVD risk factors like UNFAVCHOL and HTEN but also HHCY, as this can easily be reduced through increased intake of folic acid via supplement or foods fortified with folic acid.