Does online hemodiafiltration lead to reduction in trace elements and vitamins?

Prevalence and determinants of low plasma zinc levels in adult peritoneal dialysis patients

OBJECTIVE

Zinc is an essential trace element, being a cofactor for almost 300 enzymes. As zinc is widely available in the diet, the European Best Practice Guidelines do not recommend routine supplementation in dialysis patients. However, some medicines prescribed to dialysis patients may potentially reduce absorption, and there may be increased losses with dialysis. As older and co-morbid patients are now treated by peritoneal dialysis (PD) we wished to determine the prevalence of patients with low plasma zinc levels.

DESIGN AND METHODS

We prospectively measured plasma zinc in 550 PD patients attending for their first peritoneal membrane assessment using atomic absorption spectroscopy. Body composition was determined by bioimpedance.

RESULTS

Plasma zinc was measured in 550 patients, mean age 58.7 years, 60.6% male, mean value 10.8 ± 2.2 umol/L, with 66.5% having low zinc levels (<11.5 umol/L). Normal plasma zinc was associated with haemoglobin (odds ratio (OR) 1.41 (95% confidence limits (95%CL) 1.22-1.63), serum albumin (OR 1.04 (95%CL 1.002-1.087), higher glucose dialysates L/day (OR 1.06 (1.001-1.129), and negatively with 24-hour urinary protein losses (OR 0.786 (95%CL 0.673-0.918) and age (OR 0.985 (95%CL 0.972-1.0). There was no association with dialysis adequacy, original renal disease or dietary protein estimation. Prescription of phosphate binders had no effect on zinc levels (10.7 ± 2.2 vs 10.8 ± 2.3 umol/L).

CONCLUSIONS

Most PD patients had low plasma zinc levels, associated with older age, probably reflecting reduced intake, urinary protein losses, and lower albumin and haemoglobin most likely linked to greater co-morbidity, low grade inflammation and volume expansion requiring higher glucose dialysates.

Water-Soluble Vitamins and Trace Elements Losses during On-Line Hemodiafiltration

Maintenance hemodialysis induces water-soluble vitamins and trace elements losses, which is why recommendations regarding potential supplementation were provided, but mainly based on conventional hemodialysis. This study′s aim was to measure the water–soluble vitamins and trace element losses during one on-line post-dilution hemodiafiltration (HDF) session. Thirty-nine patients under maintenance HDF were enrolled. We used the Theraflux^® sampler (Theradial Corp., Orvault, France) to analyze the full session dialysate mass transfer. Blood and dialysate samples were collected before and after one HDF session to measure B1, B2, B6, B9, B12, C vitamins, zinc, and selenium concentrations. Values significantly decreased for B1 (20.2%), B2 (13%), B6 (25.4%), B9 (32.6%), C (66.6%) and selenium (6.7%). No significant differences were found for vitamin B12 and zinc. The dialysate losses per session were 1.12 ± 0.88 mg for vitamin B1, 0.28 ± 0.30 mg for B2, 0.33 ± 0.09 mg for B6, 0.3 ± 0.18 mg for B9, 147.5 ± 145.50 mg for C and 25.75 ± 6.91 mg for zinc. Vitamin B12 and selenium were under detection values. In conclusion, during a standard 4hr-HDF session, we found important losses for vitamin B1, B6, B9, C and zinc, suggesting the need for regular monitoring of plasma levels and systematic supplementation of these compounds.

Water-Soluble Vitamin Levels and Supplementation in Chronic Online Hemodiafiltration Patients

Introduction

Supplementation of water-soluble vitamins is a common practice in hemodialysis patients, but dosages are largely based on conventional hemodialysis techniques. The aim of this study was to assess the status of water-soluble vitamins in patients on hemodiafiltration (HDF), and attempt to determine optimal dose of vitamin supplements.

Methods

This monocentric study included 40 patients on thrice-weekly chronic HDF. At baseline, all patients received 2 tablets of Dialvit containing B and C vitamins after each dialysis session. Predialysis samples of B and C vitamins were measured in both blood (n = 40) and a subgroup of dialysate (n = 6) samples. A second blood sample was obtained in 24 patients 3 months after dose adjustment of the vitamin supplement.

Results

At baseline, B-vitamin levels were high with, respectively, 0.4%, 10.0%, and 89.6% of patients in the low, normal, and high reference range. For vitamin C, most patients were in the normal range (5.0%, 82.5%, and 12.5% in low, normal, and high reference range). Three months after dose reduction, B vitamin levels decreased but stayed mostly at or above the normal range (1.4%, 25.7%, 72.9% in low, normal, and high reference range). Three patients (12.5%) developed vitamin C deficiency on low-dose substititon.

Conclusion

This study shows that the levels of most vitamins are above the normal range in patients on HDF receiving a classic dose of vitamin supplements, vitamin C excepted. Our study suggests that the classic dose of postdialysis vitamin B supplements may be reduced.

Serum trace metal association with response to erythropoiesis stimulating agents in incident and prevalent hemodialysis patients

Alterations in hemodialysis patients' serum trace metals have been documented. Early studies addressing associations levels of serum trace metals with erythropoietic responses and/or hematocrit generated mixed results. These studies were conducted prior to current approaches for erythropoiesis stimulating agent (ESA) drug dosing guidelines or without consideration of inflammation markers (e.g. hepcidin) important for regulation of iron availability. This study sought to determine if the serum trace metal concentrations of incident or chronic hemodialysis patients associated with the observed ESA response variability and with consideration to ESA dose response, hepcidin, and high sensitivity C-reactive protein levels. Inductively-coupled plasma-mass spectrometry was used to measure 14 serum trace metals in 29 incident and 79 prevalent dialysis patients recruited prospectively. We compared these data to three measures of ESA dose response, sex, and dialysis incidence versus dialysis prevalence. Hemoglobin was negatively associated with ESA dose and cadmium while positively associated with antimony, arsenic and lead. ESA dose was negatively associated with achieved hemoglobin and vanadium while positively associated with arsenic. ESA response was positively associated with arsenic. Vanadium, nickel, cadmium, and tin were increased in prevalent patients. Manganese was increased in incident patients. Vanadium, nickel, and arsenic increased with time on dialysis while manganese decreased. Changes in vanadium and manganese were largest and appeared to have some effect on anemia. Incident and prevalent patients' chromium and antimony levels exceeded established accepted upper limits of normal.

Efficiency and nutritional parameters in an elderly high risk population on hemodialysis and hemodiafiltration in Italy and France: different treatments with similar names?

Background

Choice of dialysis is context sensitive, explored for PD and extracorporeal dialysis, but less studied for haemodialysis (HD) and hemodiafiltration (HDF), both widely employed in Italy and France; reasons of choice and differences in prescriptions may impact on dialysis-related variables, particularly relevant in elderly, high-comorbidity patients.

Methods

The study involved two high-comorbidity in-hospital cohorts, treated in Centers with similar characteristics, in Italy (Cagliari) and France (Le Mans). All patients (204) agreed to participate. Stable cases on thrice-weekly dialysis, with at least 2 months follow-up were selected (180 patients, Males 59.4%, median age 71 years, vintage 4.3 years, Charlson index 9). Univariate and multivariate correlations between baseline data, HD-HDF, dialysis efficiency and nutritional markers were assessed.

Results

In Le Mans HDF was mainly chosen to increase efficiency (large surface dialysers, high convective volume; 76.3% of the patients), in Cagliari to improve tolerance (smaller surfaces, lower convective volume; 59% of patients). Kt/V was similar in HD and HDF, and in both settings(median Kt/V Daugirdas 2: 1.6); in the setting of high efficiency no correlation was found between Kt/V, BMI, urea, creatinine, n-PCR and phosphate. The relationship between Kt/V and albumin was divergent: a weak consensual increase was present in Cagliari, a decrease in Le Mans, suggesting a role of albumin losses with high convective volumes. In the multivariate analysis, after adjustment for other covariates (including comorbidity and type of treatment) low albumin level < 3.5 g/dl was highly correlated with setting of study: Le Mans (OR: 7.155 (2.955–17.324)). The multivariate analysis confirmed a role of type of treatment, with higher risk of low albumin levels in HDF (OR: 3.592 (1.466–8.801)), and of comorbidity (Charlson index> = 7 (OR: 3.153 (1.311–7.582)), MIS index> = 7 (OR: 5.916 (2.457–14.241)).

Conclusions

The different prescriptions of HD and HDF may have similar effects on dialysis efficiency, but diverging effects on crucial nutritional markers, such as albumin levels, probably more evident in high-comorbidity populations.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

High convection volume in online post-dilution haemodiafiltration: relevance, safety and costs

Increasing evidence suggests that treatment with online post-dilution haemodiafiltration (HDF) improves clinical outcome in patients with end-stage kidney disease, if compared with haemodialysis (HD). Although the primary analyses of three large randomized controlled trials (RCTs) showed inconclusive results, post hoc analyses of these and previous observational studies comparing online post-dilution HDF with HD showed that the risk of overall and cardiovascular mortality is lowest in patients who are treated with high-volume HDF. As such, the magnitude of the convection volume seems crucial and can be considered as the ‘dose’ of HDF. In this narrative review, the relevance of high convection volume in online post-dilution HDF is discussed. In addition, we briefly touch upon some safety and cost issues.

Variation of clinical and laboratory features in chronic dialysis patients treated with high-flux hemodialysis after switching to online hemodiafiltration

PURPOSE

The study of online hemodiafiltration (HDF) benefits over high-flux hemodialysis (HD) raises great interest. The purpose was to compare clinical and laboratory parameters in patients treated with HD who were switched to HDF.

METHODS

Forty-eight HD patients (study group) were switched to HDF, while other 521 patients remained on HD as a control group. During last 6 HD months and during first year of HDF, we determined in both groups the following parameters: monthly-weekly dialysis time, systolic and diastolic blood pressure, body mass index (BMI), interdialytic body weight gain (IBWG), blood flow rate (Qb), weekly erythropoietin-stimulating agents dose (EPO), single-pool Kt/V, calcium, phosphorus (P), hemoglobin and normalized protein catabolic ration (nPCR), plus every 3 months--albumin, parathormone (PTH), ferritin and transferrin saturation (TSAT). In both groups, parameters in the last 6 HD months were compared to those in the first 6 months and, respectively, to those in the first year of HDF.

RESULTS

In the study group, albumin and nPCR were significantly higher in the HD period not only compared to the first 6 months of HDF, but also compared to the first year of HDF. IBWG and P were higher with HD compared to the first year of HDF, but not with the first 6 months. PTH, Kt/V, Qb and EPO were higher in both HDF periods. In the control group, albumin was significantly higher in the first 6 months after the switch, but it was significantly lower in the first year. BMI, ferritin, PTH, Kt/V, Qb, TSAT and weekly dialysis time were higher in both HDF periods, while nPCR, EPO, SBP and DBP were lower. IBWG and Hb rose only during the first year after the switch, while P was lower in the first year, but not in the first 6 months.

CONCLUSIONS

Nutrition, assessed by albumin, nPCR and BMI, was not improved by HDF compared to HD. With HDF, Kt/V and phosphorus control were better, similar results were observed in the control group. A larger EPO dose was needed with HDF for maintaining a similar hemoglobin level.