Plasma ascorbic acid concentrations in prevalent patients with end-stage renal disease on hemodialysis

Assessment and management of vitamin status in children with CKD stages 2-5, on dialysis and post-transplantation: clinical practice points from the Pediatric Renal Nutrition Taskforce

Children with chronic kidney disease (CKD) are at risk for vitamin deficiency or excess. Vitamin status can be affected by diet, supplements, kidney function, medications, and dialysis. Little is known about vitamin requirements in CKD, leading to practice variation.The Pediatric Renal Nutrition Taskforce (PRNT), an international team of pediatric kidney dietitians and pediatric nephrologists, was established to develop evidence-based clinical practice points (CPPs) to address challenges and to serve as a resource for nutritional care. Questions were formulated using PICO (Patient, Intervention, Comparator, Outcomes), and literature searches undertaken to explore clinical practice from assessment to management of vitamin status in children with CKD stages 2-5, on dialysis and post-transplantation (CKD2-5D&T). The CPPs were developed and finalized using a Delphi consensus approach. We present six CPPs for vitamin management for children with CKD2-5D&T. We address assessment, intervention, and monitoring. We recommend avoiding supplementation of vitamin A and suggest water-soluble vitamin supplementation for those on dialysis. In the absence of evidence, a consistent structured approach to vitamin management that considers assessment and monitoring from dietary, physical, and biochemical viewpoints is needed. Careful consideration of the impact of accumulation, losses, comorbidities, and medications needs to be explored for the individual child and vitamin before supplementation can be considered. When supplementing, care needs to be taken not to over-prescribe. Research recommendations are suggested.

Vitamin C deficiency after kidney transplantation: a cohort and cross-sectional study of the TransplantLines biobank

PURPOSE

Vitamin C deficiency is associated with excess mortality in kidney transplant recipients (KTR). We aim to evaluate plasma vitamin C status at different post-transplantation moments and assess the main characteristics associated with vitamin C deficiency in KTR.

METHODS

Plasma vitamin C was assessed in 598 KTR at 3-, 6-, 12-, 24-, and 60-months post-transplantation, 374 late KTR with a functioning graft ≥ 1 year, and 395 potential donors. Vitamin C deficiency was defined as plasma vitamin C ≤ 28 µmol/L. Diet was assessed by a 177-item food frequency questionnaire. Data on vitamin C-containing supplements use were extracted from patient records and verified with the patients.

RESULTS

Vitamin C deficiency ranged from 46% (6-months post-transplantation) to 30% (≥ 1 year post-transplantation). At all time points, KTR had lower plasma vitamin C than potential donors (30-41 µmol/L vs 58 µmol/L). In cross-sectional analyses of the 953 KTR at their first visit ≥ 12 months after transplantation (55 ± 14 years, 62% male, eGFR 55 ± 19 mL/min/1.73 m2), the characteristics with the strongest association with vitamin C deficiency were diabetes and smoking (OR 2.67 [95% CI 1.84-3.87] and OR 1.84 [95% CI 1.16-2.91], respectively). Dietary vitamin C intake and vitamin C supplementation were associated with lower odds (OR per 100 mg/day 0.38, 95% CI 0.24-0.61 and OR 0.21, 95% CI 0.09-0.44, respectively).

CONCLUSION

Vitamin C deficiency is frequent among KTR regardless of the time after transplantation, especially among those with diabetes and active smokers. The prevalence of vitamin C deficiency was lower among KTR with higher vitamin C intake, both dietary and supplemented. Further research is warranted to assess whether correcting this modifiable risk factor could improve survival in KTR.

Demand for Water-Soluble Vitamins in a Group of Patients with CKD versus Interventions and Supplementation-A Systematic Review

BACKGROUND

Increasingly, chronic kidney disease (CKD) is becoming an inevitable consequence of obesity, metabolic syndrome, and diabetes. As the disease progresses, and through dialysis, the need for and loss of water-soluble vitamins both increase. This review article looks at the benefits and possible risks of supplementing these vitamins with the treatment of CKD.

METHODS

Data in the PubMed and Embase databases were analyzed. The keywords "chronic kidney disease", in various combinations, are associated with thiamin, riboflavin, pyridoxine, pantothenic acid, folates, niacin, cobalamin, and vitamin C. This review focuses on the possible use of water-soluble vitamin supplementation to improve pharmacological responses and the overall clinical condition of patients.

RESULTS

The mechanism of supportive supplementation is based on reducing oxidative stress, covering the increased demand and losses resulting from the treatment method. In the initial period of failure (G2-G3a), it does not require intervention, but later, especially in the case of inadequate nutrition, the inclusion of supplementation with folate and cobalamin may bring benefits. Such supplementation seems to be a necessity in patients with stage G4 or G5 (uremia). Conversely, the inclusion of additional B6 supplementation to reduce CV risk may be considered. At stage 3b and beyond (stages 4-5), the inclusion of niacin at a dose of 400-1000 mg, depending on the patient's tolerance, is required to lower the phosphate level. The inclusion of supplementation with thiamine and other water-soluble vitamins, especially in peritoneal dialysis and hemodialysis patients, is necessary for reducing dialysis losses. Allowing hemodialysis patients to take low doses of oral vitamin C effectively reduces erythropoietin dose requirements and improves anemia in functional iron-deficient patients. However, it should be considered that doses of B vitamins that are several times higher than the recommended dietary allowance of consumption may exacerbate left ventricular diastolic dysfunction in CKD patients.

CONCLUSIONS

Taking into account the research conducted so far, it seems that the use of vitamin supplementation in CKD patients may have a positive impact on the treatment process and maintaining a disease-free condition.

Vitamin C deficiency and impact of vitamin C administration among pediatric patients with advanced chronic kidney disease

BACKGROUND

Vitamin C deficiency is common in chronic kidney disease (CKD) due to losses through dialysis and dietary intake below requirement. We investigated prevalence of vitamin C deficiency and impact of vitamin C treatment in deficient/insufficient patients.

METHODS

A prospective cohort study in patients aged 1-18 years with CKD stages 4 and 5D collected demographic data including underlying disease, treatment, and anthropometric assessment. Vitamin C intake was assessed using 24-h dietary recall. Hemoglobin, iron status, serum vitamin C, and serum oxalate were measured at baseline and after treatment. Vitamin C (250 mg/day) was given orally for 3 months to deficient/insufficient patients.

RESULTS

Nineteen patients (mean age 12.00 ± 4.1 years) showed prevalence of 10.6% vitamin C insufficiency and 78.9% deficiency. There were no associations between vitamin C level and daily vitamin C intake (p = 0.64) or nutritional status (p = 0.87). Median serum vitamin C was 1.51 (0.30-1.90) mg/L. In 16 patients receiving treatment, median serum vitamin C increased from 1.30 (0.23-1.78) to 3.22 (1.77-5.96) mg/L (p = 0.008) without increasing serum oxalate (79.92 (56.6-106.84) vs. 80.47 (56.88-102.95) μmol/L, p = 0.82). However, 62.5% failed to achieve normal vitamin C levels. Ordinal regression analysis revealed patients with non-oligoanuric CKD were less likely to achieve normal vitamin C levels (β = - 3.41, p = 0.03).

CONCLUSION

We describe high prevalence of vitamin C insufficiency/deficiency among pediatric CKD patients. Vitamin C levels could not be solely predicted by nutritional status or daily intake. The treatment regimen raised serum vitamin C without increasing serum oxalate; however, it was largely insufficient to normalize levels, particularly in non-oligoanuric CKD. Graphical abstract .

Vitamin C overload may contribute to systemic oxalosis in children receiving dialysis

BACKGROUND

Malnutrition and anorexia are common in children with chronic kidney disease (CKD) and gastrostomy tubes (GT) as well as nasogastric tubes (NGT) have been recommended to maximize nutritional support. The optimal requirement of vitamin C in children with CKD remains to be defined but oxalate is a breakdown product of vitamin C. Elevated vitamin C intake and bone oxalate were identified in two formula-fed dialyzed children with negative genetic testing for primary hyperoxaluria.

METHODS

We evaluated the impact of nutritional support on serum ascorbic acid and plasma oxalate levels in 13 dialyzed infants and young children.

RESULTS

All patients were fed by GT or NGT since the first months of life; overall patients were receiving between 145 and 847% of the age-specific DRI for vitamin C. Mean serum ascorbic acid and plasma oxalate levels were elevated (244.7 ± 139.7 μM/L and 44.3 ± 23.1 μM/L, respectively), and values did not differ according to the degree of residual kidney function. Ascorbic acid levels did not correlate with oxalate levels (r = 0.44, p = 0.13).

CONCLUSIONS

Excessive vitamin C intake may contribute to oxalate accumulation in dialyzed children.

The effect of increased frequency of hemodialysis on vitamin C concentrations: an ancillary study of the randomized Frequent Hemodialysis Network (FHN) daily trial

BACKGROUND

Reports on vitamin C in HD patients have shown effects of vitamin C deficiency in association with scurvy symptoms. Dialyzability of water soluble vitamins is high, and substantial losses in those who are dialyzed more frequently were hypothesized. The randomized FHN Daily Trial compared the effects of in-center HD six versus three times per week. We studied baseline correlations between vitamin C and potentially associated parameters, and the effect of more frequent HD on circulating vitamin C concentrations.

METHODS

We studied vitamin C levels at baseline and months, 3, 5 and 11. Patients enrolled between 2007 and 2009 into the randomized FHN Daily trial in the East Coast consortium were approached for participation. Predialysis plasma samples were processed with metaphosphoric acid and frozen at - 70 °C for measurement with HPLC. Regression models between baseline log-transformed vitamin C and hemoglobin, CRP, eKt/V, ePCR and PTH, and a linear mixed-effects model to estimate the effect size of more frequent HD on plasma vitamin C, were constructed.

RESULTS

We studied 44 subjects enrolled in the FHN Daily trial (50 ± 12 years, 36% female, 29% Hispanics and 64% blacks, 60% anuric). Vitamin C correlated significantly with predialysis hemoglobin (r = 0.3; P = 0.03) and PTH (r = - 0.3, P = 0.04), respectively. Vitamin C did not significantly differ at baseline (6×/week, 25.8 ± 25.9 versus 3×/week, 32.6 ± 39.4 μmol/L) and no significant treatment effect on plasma vitamin C concentrations was found [- 26.2 (95%CI -57.5 to 5.1) μmol/L at Month 4 and - 2.5 (95%CI -15.6 to 10.6) μmol/L at Month 12.

CONCLUSIONS

Based on data from this large randomized-controlled trial no significant effect of the intervention on circulating plasma vitamin C concentrations was found, allaying the concerns that more frequent HD would affect the concentrations of water-soluble vitamins and adversely affect patient's well-being. Correlations between vitamin C and hemoglobin and PTH support the importance of vitamin C for normal bone and mineral metabolism, and anemia management.

Apple intake improves antioxidant parameters in hemodialysis patients without affecting serum potassium levels

Oxidative stress (OS) is associated with increased morbidity and mortality in hemodialysis (HD) patients, and the consumption of fruits seems to improve OS due to their antioxidant properties. Therefore, we hypothesized that Fuji apple intake improves OS markers in HD patients due to its polyphenolic compounds without increasing serum potassium levels. This trial was a 1-group, pre- and posttest comparison between 16 patients who had been on hemodialysis for at least 3 months without any acute illness or hyperkalemia. Each volunteer consumed 2 Fuji apples (~360 g) per day for 1 week. Blood samples were collected at the baseline period and after 8 days for the measurement of total antioxidant status, ascorbic acid, catalase, glutathione peroxidase, superoxide dismutase, reduced glutathione, total oxidant status, oxidative stress index, potassium, phosphorus, uric acid, glucose, and fructosamine. For tolerance evaluation, participants were asked about their bowel habits. Apple intake increased glutathione peroxidase (P = .006) and superoxide dismutase activities (P = .006) and ascorbic acid levels (P = .002). No significant changes were observed in uric acid, potassium, phosphorus, glucose, and fructosamine levels. Additionally, there was a decrease in the catalase activity (P = .021) and in the total antioxidant status values (P = .004). However, increased total oxidant status (P = .003) and oxidative stress index (P = .033) levels were observed after apple intake. In conclusion, the intake of 2 Fuji apples per day for 1 week was well tolerated and improved antioxidant parameters in HD patients without affecting serum potassium levels.

Thiamine Diphosphate Status and Dialysis-Related Losses in End-Stage Kidney Disease Patients Treated with Hemodialysis

Aim: (1) To describe the whole blood content of thiamine diphosphate (TDP), a biologically active form of vitamin B1 in end-stage kidney disease patients treated with hemodialysis (HD); (2) to establish the impact of a single HD procedure on TDP blood concentrations; and (3) to describe potential explanatory variables influencing TDP dialysis related losses, including dialysis prescription, vitamin B1 dietary intake and supplementation. Methods: Single-center, cross-sectional study in 50 clinically stable maintenance HD patients. The assessment of whole blood TDP with the High Performance Liquid Chromatography method, before and after a single, middle-week dialysis session and analysis of clinical and laboratory parameters potentially influencing TDP status Results: We report a significant difference in TDP levels before and after HD sessions - 42.5 (95% CI 38.7-46.2) μg/L and 23.6 (95% CI 18.9-28.2) μg/L, respectively (p = 0.000). The magnitude of intradialytic TDP changes is highly variable among individuals and is negatively associated only with the body weight of the patients (p < 0.013). Vitamin B1 dietary intake and supplementation do not influence whole blood TDP and dialysis-related loss of TDP. Conclusions: TDP, a bioactive compound of vitamin B1, is substantially lost during the HD procedure, and the magnitude of its loss is associated with the patient's body weight but it is not influenced by vitamin B1 dietary intake and standard supplementation dose.

Vitamins and Microelement Bioavailability in Different Stages of Chronic Kidney Disease

Chronic kidney disease (CKD) predisposes one to either deficiency or toxic excess of different micronutrients. The knowledge on micronutrients—specifically water-soluble vitamins and trace elements—in CKD is very limited. Consequently, current guidelines and recommendations are mostly based on expert opinions or poor-quality evidence. Abnormalities of micronutrient resources in CKD develop for several reasons. Dietary restrictions and anorexia lead to an insufficient micronutrient intake, while diuretics use and renal replacement therapy lead to their excessive losses. Absorption is unpredictable, and metabolism impaired. Better understanding of the micronutrient needs of CKD patients could have an impact on many complications linked to vitamin and trace element disorders, including high mortality, increased risk of atherosclerosis, inflammation, oxidative stress, anemia, polyneuropathy, encephalopathy, weakness and fragility, muscle cramps, bone disease, depression, or insomnia. Here, we summarize the up-to-date knowledge on micronutrient resources in different stages of CKD, and share our experience with the assessment of micronutrient status.

Plasma vitamin C levels in ESRD patients and occurrence of hypochromic erythrocytes

INTRODUCTION

The achievement of erythropoiesis in hemodialysis (HD) patients is typically managed with erythropoiesis-stimulating-agents (ESA's) and intravenous iron (IV-iron). Using this treatment strategy, HD patients frequently show an elevated fraction of red blood cells (RBC) with hemoglobin (Hb) content per cell that is below the normal range, called hypochromic RBC. The low Hb content per RBC is the result of the clinical challenge of providing sufficient iron content to the bone marrow during erythropoiesis. Vitamin C supplements have been used to increase Hb levels in HD patients with refractory anemia, which supports the hypothesis that vitamin C mobilizes iron needed for Hb synthesis.

METHODS

We conducted a cross-sectional survey in 149 prevalent HD patients of the percent hypochromic RBC, defined as RBC with Hb < 300 ng/uL of packed RBC, in relation to plasma vitamin C levels. We also measured high-sensitivity CRP, (hs-CRP), iron, and ferritin levels. and calculated ESA dose.

FINDINGS

High plasma levels of vitamin C were negatively associated with hypochromic RBC (P < 0.003), and high ESA doses were positively associated (P < 0.001). There was no significant association of hs-CRP with percent hypochromic RBC.

DISCUSSION

This finding supports the hypothesis that vitamin C mobilizes iron stores, improves iron delivery to the bone marrow, and increase the fraction of RBC with normal Hb content. Further research is warranted on development of protocols for safe and effective use of supplemental vitamin C for management of renal anemia.

Gingival Bleeding and Bloody Dialysate: A Case Report of Scurvy in a Child With End-Stage Renal Disease Receiving Peritoneal Dialysis

Patients with chronic kidney disease (CKD) or end-stage renal disease are at risk for vitamin C deficiency and scurvy due to diet restriction, increased urinary loss of the water-soluble vitamin C with diuretics, and in case of patients who are on dialysis, through dialysates. The condition may be overlooked as the clinical manifestation of scurvy may be subtle, and some presentations may mimic clinical signs in CKD. We reported a case of scurvy presenting with gingival bleeding and blood dialysate in a 6-year-old girl with end-stage renal disease who was on continuous ambulatory peritoneal dialysis. Physical examination showed gingival hyperplasia and bleeding, and the pathognomonic bleeding of perifollicular hemorrhage. The typical radiographic changes were present. The clinical signs and symptoms resolved after ascorbic acid treatment. This case underscores the importance of awareness of the increased risk for vitamin C deficiency in patients with CKD and receiving dialysis.

Impulsive mathematical modeling of ascorbic acid metabolism in healthy subjects

In this work, we develop an impulsive mathematical model of Vitamin C (ascorbic acid) metabolism in healthy subjects for daily intake over a long period of time. The model includes the dynamics of ascorbic acid plasma concentration, the ascorbic acid absorption in the intestines and a novel approach to quantify the glomerular excretion of ascorbic acid. We investigate qualitative and quantitative dynamics. We show the existence and uniqueness of the global asymptotic stability of the periodic solution. We also perform a numerical simulation for the entire time period based on published data reporting parameters reflecting ascorbic acid metabolism at different oral doses of ascorbic acid.