Folic acid, pyridoxine, cobalamin, and homocysteine and their relationship to cardiovascular disease in end-stage renal disease

α1-Acid Glycoprotein and Dietary Intake in End-Stage Renal Disease Patients

Management of end-stage renal disease (ESRD) patients requires monitoring each of the components of malnutrition–inflammation–atherosclerosis (MIA) syndrome. Restrictive diet can negatively affect nutritional status and inflammation. An acute-phase protein—α₁-acid glycoprotein (AGP), has been associated with energy metabolism in animal and human studies. The aim of our study was to look for a relationship between serum AGP concentrations, laboratory parameters, and nutrient intake in ESRD patients. The study included 59 patients treated with maintenance hemodialysis. A 24 h recall assessed dietary intake during four non-consecutive days—two days in the post-summer period, and two post-winter. Selected laboratory tests were performed: complete blood count, serum iron, total iron biding capacity (TIBC) and unsaturated iron biding capacity (UIBC), vitamin D, AGP, C-reactive protein (CRP), albumin, prealbumin, and phosphate–calcium metabolism markers (intact parathyroid hormone, calcium, phosphate). Recorded dietary intake was highly deficient. A majority of patients did not meet recommended daily requirements for energy, protein, fiber, iron, magnesium, folate, and vitamin D. AGP correlated positively with CRP (R = 0.66), platelets (R = 0.29), and negatively with iron (R = −0.27) and TIBC (R = −0.30). AGP correlated negatively with the dietary intake of plant protein (R = −0.40), potassium (R = −0.27), copper (R = −0.30), vitamin B₆ (R = −0.27), and folates (R = −0.27), p < 0.05. However, in multiple regression adjusted for confounders, only CRP was significantly associated with AGP. Our results indicate that in hemodialyzed patients, serum AGP is weakly associated with dietary intake of several nutrients, including plant protein.

Guidelines by An AD HOC European Committee on the Assessment of Growth and Nutrition Status in Children on Chronic Peritoneal Dialysis

If children are to thrive and grow on chronic peritoneal dialysis (CPD), close attention to their nutrition needs is required, with dietetic support being an essential part of the multidisciplinary team approach. This paper offers a practical approach to the assessment of growth and nutrition status in children on CPD under a combined medical and dietetic strategy.

Vitamin and trace element deficiencies in the pediatric dialysis patient

Pediatric dialysis patients are at risk of nutritional illness secondary to deficiencies in water-soluble vitamins and trace elements. Unlike 25-OH vitamin D, most other vitamins and trace elements are not routinely monitored in the blood and, consequently, the detection of any deficiency may not occur until significant complications develop. Causes of vitamin and trace element deficiency in patients on maintenance dialysis patient are multifactorial, ranging from diminished nutritional intake to altered metabolism as well as dialysate-driven losses of water-soluble vitamins and select trace elements. In this review we summarize the nutritional sources of key water-soluble vitamins and trace elements with a focus on the biological roles and clinical manifestations of their respective deficiency to augment awareness of potential nutritional illness in pediatric patients receiving maintenance dialysis. The limited pediatric data on the topic of clearance of water-soluble vitamins and trace elements by individual dialysis modality are reviewed, including a brief discussion on clearance of water-soluble vitamins and trace elements with continuous renal replacement therapy.

Fuzzy role of hyperhomocysteinemia in hemodialysis patients’ mortality

Recent studies give contradictory data regarding the role of hyperhomocysteinemia (hyperHcy) in cardiovascular (CV) morbidity and mortality in hemodialysis (HD) patients. The aims of the present study were to detect the most powerful variables associated with hyperHcy as well as to evaluate the relationship between hyperHcy and CV morbidity and mortality. The prospective follow-up study of 113 patients (52 males, aged 55.2+/-13.1 years) maintained by HD for 81.9+/-56.9 months at our Institute was carried out over 55 months. Fifty-seven (50.4%) of the examined patients were supplemented with water-soluble vitamins including folic acid and vitamin B complex pills or ampoules. Total serum Hcy level was determined by high-performance liquid chromatography, while serum folic acid and vitamin B(12) were measured by radioimmunoassay. The multivariate analysis showed HD duration (r=0.608; P=0.02) and folic acid serum level (r=-0.580; P=0.03) to be significant predictors of serum tHcy concentration. The multivariate Cox regression analysis of CV mortality revealed diabetes mellitus and heart failure as the most powerful positive predictors, while creatinine, albumin and vitamins intake therapy were negative predictors of CV mortality. Long-term supplementation with the usual doses of vitamins is followed with increased survival in hemodialysis patients. Although total serum Hcy level was not found to be a predictor of overall and CV mortality, the role of hyperHcy. as risk factor for CVD cannot be excluded in hemodialysis patients.

International variation in vitamin prescription and association with mortality in the dialysis outcomes and practice patterns study (DOPPS)

BACKGROUND

The prevalence of water-soluble vitamin use among hemodialysis (HD) patients and whether mortality and hospitalization are associated with water-soluble vitamin use by HD patients have not previously been reported. The present study investigates patterns of water-soluble vitamin use among HD patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) I and evaluates outcomes associated with vitamin use.

METHODS

The study sample came from the DOPPS I, a prospective observational study of adult HD patients (N = 16,345) randomly selected from 308 representative dialysis facilities in France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States. Time-dependent Cox regression models were used to assess relative risk (RR) for mortality and hospitalization for patients administered water-soluble vitamins versus those not administered water-soluble vitamins.

RESULTS

There was large variation by region in the percentage of patients administered water-soluble vitamins: Europe ranged from a low of 3.7% in the United Kingdom to a high of 37.9% in Spain; 5.6% in Japan; and 71.9% in the United States. Patient use of water-soluble vitamins was associated with a substantially and significantly lower risk for mortality (RR, 0.84; P = 0.001). Lower RR for facility-level mortality also was associated with greater water-soluble vitamin use (RR, 0.98; P = 0.05 per 10% more patients administered water-soluble vitamins at the facility).

CONCLUSION

Although only a randomized trial could prove that water-soluble vitamins improve outcomes, use of water-soluble vitamins is a minimal-risk practice pattern associated with improved outcomes in this prospective observational study.

Comparison of two micronutrient supplements in children with chronic renal failure

OBJECTIVE

To compare a newly formulated renal-specific micronutrient (RSM) supplement (vitamins C, E, K, and B complex, copper, zinc) with Ketovite (Paines & Byrnes, Middlesex, UK) tablets (vitamins C, E, K, and B complex) in children with chronic renal failure (glomerular filtration rate [GFR] < 25 mL/min/1.73 m(2)) or on chronic peritoneal dialysis (CPD) and hemodialysis (HD).

DESIGN

Children currently prescribed Ketovite tablets were changed to RSM for 3 months. Questionnaires on palatability, acceptability, and ease of administration were assessed while on Ketovite and after 3 months on RSM along with plasma levels of zinc, copper, folate (serum, red cell), vitamin B(12), and homocysteine.

SETTING

Regional pediatric nephrology unit.

PATIENTS

Fifteen children (10 male) with a mean age of 10.4 years (range, 1.1 to 16 y) were recruited (11 had GFR < 25 mL/min/1.73 m(2), 2 CPD, 2 HD). Two children received overnight gastrostomy button feeding.

MAIN OUTCOME MEASURES

Fourteen children (1 child refused RSM after 1 week) and their families completed questionnaires using a Likert scale: 1 (liked) to 7 (disliked). Plasma levels were analyzed at baseline on Ketovite and after 3 months on RSM.

RESULTS

Children disliked the smell of Ketovite compared with RSM (P =.004). The size of Ketovite was preferable to the size of the RSM (P =.015) and was believed to be easier to administer (P =.046). There were no differences in patient/parent rating of appearance, texture, or taste, but 8 of 15 patients (53%) expressed a preference for the RSM if available. Plasma values of copper, zinc, folate, and vitamin B(12) were within the normal reference range on Ketovite and showed no significant change on RSM. Mean plasma homocysteine levels were above normal reference ranges in all groups (GFR < 25 mL/min/1.73 m(2), 7.6 [SD, 3.1]; CPD, 11.5 [SD, 1.6]; HD, 12 [SD, 8.7]) on Ketovite and were unchanged after 3 months on RSM.

CONCLUSIONS

This pilot study confirms the acceptability of the RSM, particularly in relation to its smell and chewability, but the current size may preclude its widespread use. The incorporation of zinc and copper will be beneficial for many children, but reduction in homocysteine levels may necessitate an increase in folic acid content.

An MTHFR variant, homocysteine, and cardiovascular comorbidity in renal disease

BACKGROUND

It is unclear whether total serum homocysteine (tHcy) and the C677T mutation of methylenetetrahydrofolate reductase (MTHFR) are associated with cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD).

METHODS

A cross-sectional sample of 459 patients with ESRD on chronic dialysis was assessed to determine whether tHcy and the C677T mutation are associated with CVD prevalence in multiple logistic regression. As CVD mortality is high, we examined the relationship between homozygosity and duration of dialysis.

RESULTS

Mean tHcy was higher in patients without a history of CVD (35.2 micromol/L vs. 30.4 micromol/L, P = 0.02). In multivariate models, CVD was negatively associated with tHcy and positively associated with TT genotype, male gender, and body mass index. Mean tHcy levels were higher among those with the TT genotype compared with those with the CC genotype when adjusted for age, folate, creatinine, and albumin (37.9 micromol/L vs. 31.9 micromol/L, P = 0.005). Among whites, the prevalence of the TT genotype was higher in those having undergone less than one year of dialysis (P = 0.002).

CONCLUSIONS

The C677T genotype of MTHFR is associated with CVD in ESRD and may be a more meaningful marker than tHcy for abnormal homocysteine metabolism in ESRD. Prospective data from ongoing clinical trials are needed to improve our understanding of these findings. Screening for this polymorphism may help guide prevention measures.

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 cardiovascular risk factor and is found in more than 85% of patients on maintenance haemodialysis. Previous studies have shown that folic acid can lower circulating homocysteine in dialysis patients. We evaluated prospectively the effect of increasing the folic acid dosage from 1 to 6 mg per dialysis on plasma total homocysteine levels of haemodialysis patients with and without a history of occlusive vascular artery disease (OVD).

METHODS

Thirty-nine stable patients on high-flux dialysis were studied. Their 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 years prior to the study, the patients had received an oral post-dialysis multivitamin supplement including 1 mg of folic acid per dialysis. After baseline determinations, the folic acid dose was increased from 1 to 6 mg/dialysis for 3 months.

RESULTS

After 3 months, plasma homocysteine had decreased significantly by approximately 23% from 31.1 +/- 12.7 to 24.5 +/- 9 micromol/l (P = 0.0005), while folic acid concentrations had increased from 6.5 +/- 2.5 to 14.4+/-2.5 microg/l (P < 0.0001). However, the decrease of homocysteine was quite different in patients with and in those without OVD. In patients with OVD, homocysteine decreased only marginally by approximately 2.5% (from 29.0 +/- 10.3 to 28.3 +/- 8.4 micromol/l, P = 0.74), whereas in patients without OVD there was a significant reduction of approximately 34% (from 32.7+/-14.4 to 21.6+/-8.6 micromol/l, P = 0.0008). Plasma homocysteine levels were reduced 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 patients (0%) in the former group compared with 13 (59%) in the latter (P = 0.001).

CONCLUSIONS

These results indicate that the homocysteine-lowering effect of folic acid administration appears to be less effective in haemodialysis patients having occlusive vascular disease than in those without evidence of such disease.

Hyperhomocysteinemia in hemodialysis patients: effects of 12-month supplementation with hydrosoluble vitamins

BACKGROUND

High-efficiency hemodialysis may induce a deficiency in hydrosoluble vitamins. Supplementation with B-complex vitamins has been shown to lower serum homocysteine concentrations in several groups, but relatively few studies have concerned hemodialysis patients. Our objectives were to determine the status in B-complex vitamins in a large cohort of unsupplemented hemodialysis patients and to assess the effects of supplementation with hydrosoluble vitamins on serum homocysteine over one year.

METHODS

Serum total homocysteine (tHcy), vitamin B12, folate, pyridoxal-5'-phosphate (P-5'-P; the active moiety of vitamin B6), as well as red blood cell folate concentrations, were measured in 168 chronic dialysis patients on three times weekly high-efficiency hemodialysis and not supplemented with hydrosoluble vitamins. Their methylenetetrahydrofolate reductase C677T (MTHFR) genotypes were also determined (homozygotes TT, heterozygotes CT, without mutation CC). All involved patients were then supplemented with hydrosoluble vitamins (once daily by mouth, DiaVite; R&D Laboratories, Minneapolis, MN, USA), and half of them were randomized to receive in addition 10 mg intravenously of folic acid posthemodialysis (30 mg intravenously per week). Serum tHcy was monitored after 6 and 12 months of supplementation in the 140 and 128 patients available for follow-up.

RESULTS

At baseline, serum and red blood cell folate concentrations were within normal limits in all patients except for two with borderline serum folate (mean values of 21 +/- 8 and 1195 +/- 454 nmol/L), whereas serum vitamin B12 and P-5'-P were below normal in 11 and 65 patients, respectively (mean values of 327 +/- 215 pmol/L and 19 +/- 16 nmol/L for the 168 patients). Initial tHcy levels were increased in all patients (mean 33.3 +/- 16.6 for a normal below 11.8 +/- 1.5 micromol/L); tHcy significantly decreased to 23.5 +/- 7.6 micromol/L after six months (P < 0.0001 vs. baseline) and to 21.7 +/- 6.1 micromol/L after 12 months (P < 0.0001 vs. baseline) for the entire group, but was normalized in only four patients at 12 months. After six months, the mean reduction in tHcy was slightly but significantly greater for patients receiving intravenous folic acid (12.2 +/- 18.5 micromol/L) compared with patients not receiving it (8.3 +/- 9.8 micromol/L, P < 0.05). However, at 12 months, no difference between both subgroups persisted. When considering the different genotypes, tHcy at baseline tended to be higher for TT than CT and CC (39.8 +/- 30.9 vs. 31.4 +/- 10.5 vs. 31.6 +/- 11.8 micromol/L) and decreased to respective values of 21.1 +/- 6.9 versus 21.4 +/- 6.1 versus 22.2 +/- 5.9 micromol/L at 12 months. The impact of the addition of folic acid to DiaVite appeared particularly significant in TT patients at six months.

CONCLUSIONS

(1) Hyperhomocysteinemia was present in 100% of our hemodialysis patients. (2) Nearly 40% of our unsupplemented hemodialysis patients were deficient in vitamin B6. (3) Supplementation with DiaVite(R) has resulted in significant tHcy reductions for all three genotypes. (4) The impact of the proposed supplementation protocol was found after six months and was maintained, but did not increase further after 12 months of the same regimen. (5) The addition of intravenous folic acid has been associated with a more pronounced decrease in tHcy in TT patients.