Water-Soluble Vitamin Status in Patients With Renal Disease Treated With Hemodialysis or Peritoneal Dialysis

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.

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.

Folic acid supplementation and cardiac and stroke mortality among hemodialysis patients

OBJECTIVE

We sought to assess whether the use of folic acid vitamin supplements reduced cardiac and stroke mortality in hemodialysis patients. Further, we examined whether the consumption of folic acid from vitamin supplements >1000 microg compared with the standard 1000 microg, and 1000 microg compared with either a lower dose or no consumption, were associated with reduced cardiac and stroke mortality risk.

DESIGN

We performed a secondary analysis of data from the Hemodialysis Study, a randomized clinical trial examining dialysis treatment regimens over a 3-year follow-up.

PARTICIPANTS

Participants included 1846 hemodialysis patients previously participating in the Hemodialysis Study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURE

Cardiac and stroke mortality were our main outcome measures.

RESULTS

Based on time-dependent Cox proportional hazard regression models, folic acid consumption from vitamin supplements, above or below the standard 1000-microg dose, was not associated with a decrease or increase in cardiac mortality (P = .53, above vs. standard dose; P = .46, below vs. standard dose). There was also no association between folic acid consumption and mortality from stroke (P = .27, above vs. standard dose; P = .64, below vs. standard dose).

CONCLUSION

The consumption of higher than the standard 1000-microg prescribed dose of folic acid was not beneficial in reducing cardiac or stroke mortality in hemodialysis patients. Similarly, the consumption of less than the standard dose was not associated with an increase in either cardiac or stroke mortality.

Medical nutrition therapy in chronic kidney failure: Integrating clinical practice guidelines

This review updates earlier published recommendations and integrates current clinical practice guidelines for nutritional care in chronic kidney disease as recommended by the National Kidney Foundation Kidney Dialysis Outcome Quality Initiative (K/DOQI). The scope covers chronic kidney disease in adults prior to kidney failure (Stages 1-4), chronic kidney failure with hemodialysis or peritoneal dialysis replacement therapy (Stage 5), and management after kidney transplantation. Multiple diet parameters are necessary to provide optimal nutritional health, including monitoring of calories, protein, sodium, fluid, potassium, calcium, and phosphorus, as well as other individualized nutrients. Emphasis is placed on continuity of care within changing kidney function and treatment modality status. The rising incidence of chronic kidney disease will increase the probability of the non-renal specialist dietetics professional delivering care to this patient population.

Hyperhomocysteinemia in chronic renal failure patients: relation to nutritional status and cardiovascular disease

A moderate increase in plasma total homocysteine (tHcy) is considered to be an independent risk factor for cardiovascular disease (CVD) in the general population. Almost all chronic renal failure (CRF) patients have plasma concentration of tHcy that is elevated 3 to 4 times above normal. The prevalence of CVD, diabetes mellitus, malnutrition and hypoalbuminemia is high in CRF patients. Previous investigations have focused on the role of vitamin status on plasma tHcy in CRF patients, but little information exists on the influence of nutritional status and hypoalbuminemia on plasma tHcy in CRF, although a substantial fraction of tHcy (>70%) is protein-bound, mainly to albumin. Our study in patients with end-stage renal disease showed that more than 90% of the patients had elevated plasma tHcy levels, which were higher in patients with normal nutritional status than in malnourished patients. Moreover, plasma tHcy was inversely correlated with subjective global nutritional assessment (high values denote malnutrition) and positively correlated with serum albumin and protein intake. Hence, it seems likely that serum-albumin is a strong determinant of plasma tHcy in CRF patients and this may contribute to the lower tHcy levels in malnourished patients. Patients with diabetes mellitus had lower serum-albumin and plasma tHcy than non-diabetic patients, irrespective whether they were malnourished or not. Patients with CVD had lower (although still elevated) plasma tHcy levels than those without CVD. An explanation may be that the prevalence of diabetes mellitus, malnutrition and hypoalbuminema, i.e. factors that decrease tHcy, was higher in patients with CVD, which may explain why they had less elevated values. Assuming that hyperhomocysteinemia carries an independent risk of CVD, this implies that almost all CRF patients are exposed to this risk. CRF patients with CVD had a higher prevalence of malnutrition, hypoalbuminemia and diabetes mellitus, which was associated with a lower plasma Hcy level. This may explain why plasma tHcy was lower (although still abnormally high) in patients with CVD than in patients without CVD. The lower tHcy levels in CVD patients do not contradict the assumption that hyperhomocysteinemia is a risk factor for CVD since almost all patients are exposed to this risk, and other factors might be present that confound the relationship between the absolute tHcy levels and CVD. Our findings imply that nutritional status and serum albumin, as well as the presence of diabetes mellitus, should be taken into consideration when evaluating tHcy as a risk factor for CVD in CRF patients.

The role of the dietitian in a multicenter clinical trial of dialysis therapy: the Hemodialysis (HEMO) Study

The Hemodialysis (HEMO) Study is a randomized multicenter prospective clinical trial, supported by the National Institute of Diabetes, Digestive, and Kidney Diseases of the National Institutes of Health. The trial is designed to assess the effects of a standard versus higher dialysis dose and low versus high dialysis membrane flux on morbidity and mortality of chronic hemodialysis patients. The role of the dietitian in the HEMO Study is to support and maintain the nutritional status of randomized participants. To ensure participant safety, nutritional status is closely monitored by a variety of biochemical and participant-reported parameters. Serum albumin and equilibrated normalized protein catabolic rates are obtained monthly. Appetite assessment and dietary energy and protein intakes using a 2-day diet diary assisted recall are ascertained at baseline and on a yearly basis. Consumption of vitamins, minerals, and nutritional supplements, including oral enterals, tube feedings, and parenteral nutrition, is obtained at least once a year. In addition, anthropometry is performed at baseline and on a yearly basis. Prespecified changes in serum albumin level or body weight trigger action by the dietitian to prevent protein calorie malnutrition. The HEMO Study dietitians play a vital role in carrying out the nutrition program for the trial. The HEMO Study should provide important information about the natural history of the nutritional status of chronic hemodialysis patients and the impact of dialysis dose and dialysis membrane flux on these parameters.

Water-soluble vitamin levels in patients undergoing high-flux hemodialysis and receiving long-term oral postdialysis vitamin supplementation

The prescription of multivitamin supplements for dialysis patients is routine practice, but the doses prescribed differ greatly from one dialysis center to another. Few data are available concerning long-term vitamin supplementation and its effects on patients either on high-flux hemodialysis or receiving postdialysis supplementation. For several years, we have systematically prescribed to our patients an oral postdialysis multivitamin supplement containing thiamine hydrochloride 100 mg, riboflavin 20 mg, pyridoxine hydrochloride 50 mg, folic acid 6 mg, and ascorbic acid 500 mg. The aim of this study was to perform a cross-sectional long-term evaluation of the vitamin levels in patients who received this vitamin supplement for at least 12 months. We also were interested in investigating the plasma oxalic acid and total homocysteine levels associated with the long-term prescription of these vitamin supplements. Thirty-three patients on high-flux dialysis were studied. Vitamin levels and/or vitamin-dependent enzymatic activities were within the normal range (N) in all patients. The mean results (+/-SD) were plasma ascorbic acid 13.6 +/- 6.4 mg/L (N > 4), plasma folate 14.1 +/- 1.1 microg/L (N > 3), for vitamin B1, alpha-ETK 1.02 +/- 0.02 (N < 1.18) and ETKo 100 +/- 13 U/L (N > 70), for vitamin B2, alpha-EGR 1.00 +/- 0.07 (N < 1.52) and EGRo 1282 +/- 213 U/L (N > 672), and for vitamin B6, alpha-EGOT 1.34 +/- 0.10 (N < 1.8) and EGOTo 380 +/- 84 U/L (N > 228). Plasma oxalic acid was higher than normal in all patients (mean = 61 +/- 15 micromol/L, N < 33). However, all patients had oxalic acid levels within the range reported in the literature for patients not taking extra ascorbic acid. Mean total homocysteine was 24 +/- 8 micromol/L with only 4 patients (12%) having normal levels (N < 15). In conclusion, the postdialysis supplement given provides adequate vitamin levels in almost all patients in the long term. Postdialysis prescription allows an optimal compliance with the treatment, is well accepted by the patients, and is cost-effective.

Vitamin B6 supplementation can improve peripheral polyneuropathy in patients with chronic renal failure on high-flux haemodialysis and human recombinant erythropoietin

BACKGROUND

High-flux haemodialysis (HD) has recently been vigorously promoted as a novel standard, and it can indeed efficiently reduce the occurrence of most uraemic symptoms due to middle molecular toxins and/or underdialysis. However, some symptoms remain problematical, particularly peripheral polyneuropathy (PPN). One of the possible reasons for this is that the patients may have low concentrations of some nutrients, e.g. vitamin B(6), necessary for normal peripheral neuron function.

METHODS

Predialysis serum pyridoxal-5'-phosphate (P5P) level was determined in 36 chronic HD patients who were undergoing high-flux HD and receiving human recombinant erythropoietin. Among them, 26 patients suffered from PPN. Prior to supplementation, these 26 patients were examined and their neurological symptoms were ranked according to our PPN symptom score. Vitamin B(6) (60 mg/day) was randomly prescribed to 14 of them, and vitamin B(12) (500 microg/day) was prescribed to the others. After 4 weeks, all the patients were re-examined.

RESULTS

We found that predialysis serum P5P levels of HD patients with PPN were not significantly lower than those of matched HD patients without PPN. Nonetheless, it was demonstrated that supplementation with vitamin B(6) for 4 weeks significantly increased the predialysis level of P5P and dramatically attenuated PPN symptoms compared with initial symptoms. No improvement was observed in response to vitamin B(12) supplementation.

CONCLUSION

This result suggests that although vitamin B(6) deficiency could not be demonstrated in patients with chronic renal failure on high-flux HD, vitamin B(6) supplementation was effective in improving PPN symptoms of various aetiologies, possibly because of vitamin B(6) resistance to PPN in these patients.

Disintegration performance of renal multivitamin supplements

OBJECTIVE

Vitamins have traditionally been regulated as dietary supplements and have not been required to meet the same rigorous product quality performance standards as drug products. Impaired product performance, such as failure to disintegrate and/or dissolve in the gastrointestinal tract, could limit the absorption of vitamins. Furthermore, patients with renal disease have been reported to experience a wide range in gastrointestinal pH, which could influence a product's performance. The purpose of this study was to determine the effect of pH on the in vitro disintegration of renal multivitamin supplements.

DESIGN

Products were studied using the United States Pharmacopeial Convention standard disintegration apparatus. Products were tested in simulated gastric fluid, neutral fluid, and intestinal fluid. Product failure was defined as two or more individual tablets or capsules failing to disintegrate completely within compendial limits.

RESULTS

Of 11 products tested, 4 products failed the disintegration study test in all pH conditions. Sixty-four percent of the products showed statistically significant differences in disintegration time (DT) based on pH. As pH increased, time to disintegration increased.

CONCLUSION

The DT of commercially available renal multivitamin supplements was highly variable. Poorest product performance was shown in simulated intestinal fluid. The pH significantly affected in vitro disintegration in greater than half the products tested. How this affects dissolution and in vivo performance has yet to be studied.

The hemodialysis pilot study: nutrition program and participant characteristics at baseline. The HEMO Study Group

OBJECTIVE

Describe the nutrition program (assessments and interventions) and the participants' baseline nutritional characteristics in the Hemodialysis Pilot Study.

DESIGN

Cross sectional survey in which hemodialysis patients were examined during 10 weeks of baseline (BL), before randomization study interventions (dose and flux).

SETTING

Four hemodialysis centers (eight dialysis units in total).

PATIENTS

Twenty-nine male (mean age, 63 years; range, 34 to 75) and 20 female (mean age, 61 years; range, 29 to 73) hemodialysis patients.

INTERVENTIONS

None during BL.

MAIN OUTCOME MEASURES

Feasibility of implementing the proposed nutrition program before conducting the full-scale trial, and description of baseline characteristics related to nutrition.

RESULTS

A nutrition program was developed to assess nutritional status during BL and follow-up periods and to intervene in patients with weight loss or decreasing serum albumin. Methods for collecting biochemical, dietary and anthropometric data were implemented at four clinical centers. At baseline, mean protein intake estimated by single pool normalized protein catabolic rate was 0.95 +/- 0.21 gm/kg adjusted body weight (ABW) (n = 42) and by diet record assisted recalls (n = 47) 0.94 +/- 0.36 gm/kg ABW/d, respectively. Mean energy intake was 22.8 +/- 8 kcal/kg ABW/day (n = 39). Mean serum albumin concentration using the bromcresol green method was 3.8 +/- 0.4 gm/dL (n = 40). Mean body mass index was within the normal limits of 19-27 kg/m2. Mean skinfold thicknesses in females, but not males, were shifted toward the lower end of usual distributions for healthy individuals.

CONCLUSIONS

The goal of designing, developing, and implementing the diet and nutrition component, and related data collection for the HEMO pilot study was accomplished at four separate clinical centers. Baseline mean protein and energy intake were low, suggesting that continuing dietary surveillance is needed. The ongoing full-scale HEMO study will provide the first prospective analysis of dietary intake, nutritional status, and outcome in maintenance hemodialysis patients as a function of dialysis dose and membrane flux.

Vitamin B6 and hemodialysis: the impact of high-flux/high-efficiency dialysis and review of the literature

High-flux/high-efficiency (HF/HE) dialysis is associated with improved clearance for larger molecules, which include a wide variety of middle molecules and water-soluble vitamins. Our study attempted to measure in vivo clearances of serum pyridoxal-5'-phosphate (PLP), the active metabolite of vitamin B6, on standard cuprophan versus cellulose triacetate HF/HE dialysis for patients maintained on 10 mg daily pyridoxine supplements. A longitudinal evaluation of PLP after 3 months on HF/HE dialysis was performed simultaneously. The average in vivo PLP clearance for six patients on standard hemodialysis increased by more than 50%, from 86 +/- 61.7 mL/min using a cuprophan membrane to 173 +/- 90.2 mL/min using a cellulose triacetate dialyzer, at average blood flows of 375 mL/min (P < 0.05). Levels of PLP decreased from a baseline of 50 +/- 13.8 ng/mL to 24 +/- 9.7 ng/mL (P < 0.05) after 3 months of HF/HE treatments; the levels returned to 45 +/- 6.4 ng/mL on resumption of standard dialysis treatments. Although not achieving statistical significance, the average hematocrit increased from 31.2% +/- 1.66% to 32.7% +/- 1.24% while on HF/HE dialysis without an increase in erythropoietin requirements. We conclude that HF/HE dialysis treatments can have a dramatic impact on vitamin B6 homeostasis. Further investigation to evaluate the effects of different membranes and reprocessing should be performed on more heterogeneous patient populations in whom compliance problems with diet and vitamin supplementation may exist. The increased clearance of vitamin B6 may have significantly more detrimental effects in these settings.

Which diet for which renal failure: making sense of the options

This review describes categories of renal function (normal, renal insufficiency, end-stage renal failure), types of treatment modalities (renal insufficiency management, dialysis, transplantation), and corresponding dietary parameters (protein, energy, fiber, sodium, fluid, potassium, phosphorus, calcium, vitamins, minerals). The focus is directed toward general and nonrenal specialty practitioners, who are encountering a growing number of geriatric patients and patients who have undergone renal transplantation or are in early renal failure. The findings indicate that early intervention may delay or prevent rapid progression of renal disease in some patients, that treatment modalities continue to need individualized dietary support to maintain nutritional status, and that transplant goals should include control of obesity and hyperlipidemia to reduce cardiovascular mortality.

Vitamin status of infants receiving long-term peritoneal dialysis

The oral vitamin intakes and blood vitamin concentrations of seven infants receiving long-term peritoneal dialysis were measured. The serum concentrations of vitamin A, vitamin B12, vitamin C and folic acid were determined. Thiamine and riboflavin were assessed by the activation of erythrocyte transketolase and erythrocyte glutathione reductase, respectively. Vitamin B6 was measured as plasma pyridoxal phosphate. All patients received a daily vitamin supplement devoid of vitamin A. Dietary vitamin intake was derived from infant formula. In all cases, the patients' blood concentrations of the water-soluble vitamins were equal to or greater than normal infant values. Serum vitamin A levels were elevated despite the lack of supplementation. The combined dietary/supplemental water-soluble vitamin intake of the patients exceeded the recommended daily allowance in all but one patient. These preliminary data emphasize the need to further evaluate the vitamin requirements of infants receiving long-term peritoneal dialysis.