Parenteral ascorbic acid in haemodialysis patients

Relationship between anti-erythropoietin receptor autoantibodies and responsiveness to erythropoiesis-stimulating agents in patients on hemodialysis: a multi-center cross-sectional study

BACKGROUND

A decreased response to erythropoiesis-stimulating agents (ESAs) leads to refractory anemia and worse prognosis in patients with chronic kidney disease. We examined the association between autoantibodies to the erythropoietin receptor (EPOR) and responsiveness to ESAs in patients on maintenance hemodialysis.

METHODS

A total of 108 Japanese patients on maintenance hemodialysis at three institutions were enrolled. Sera from these patients were screened for anti-EPOR antibodies using an enzyme-linked immunosorbent assay. An ESA resistance index (ERI) was calculated, and patients in the highest ERI quartile were defined as ESA hyporesponsive.

RESULTS

Anti-EPOR antibodies were detected in 11 patients (10%). Body mass index and hemoglobin, platelet, magnesium, and ferritin levels decreased with higher ERI levels. On the other hand, C-reactive protein (CRP) levels and the prevalence of anti-EPOR antibodies increased with higher ERI levels. In multivariate analysis, the presence of anti-EPOR antibodies together with CRP was a significant risk factor for ESA hyporesponsiveness.

CONCLUSIONS

Anti-EPOR antibodies were detected in patients on maintenance hemodialysis, and these autoantibodies were independent factors for hyporesponsiveness to ESAs in these patients.

Ascorbate- and zinc-responsive parkinsonism

OBJECTIVE

To report a case of Parkinsonism rapidly responsive to intravenous replacement of vitamin C and zinc.

CASE SUMMARY

A 66-year-old man with Parkinsonism, pleural effusion, and bipolar disorder was found to have low serum vitamin C and zinc levels. Intravenous replacement of these micronutrients led to resolution of the movement disorder in less than 24 hours.

DISCUSSION

Parkinsonism has been associated with vitamin C deficiency, and recent cases of scurvy complicated by Parkinsonism have responded well to intravenous replacement of vitamin C. In this case, deficiency of zinc may have contributed to the development of a movement disorder. The likely pathophysiology of, and treatment recommendations for, Parkinsonism linked to deficiencies of vitamin C and zinc are reviewed.

CONCLUSIONS

Whereas vitamin C has a strong link with Parkinsonism, the potential role of zinc has only been suspected. This case report highlights some of the potential links between zinc deficiency and Parkinsonism.

Water-soluble vitamins in people with low glomerular filtration rate or on dialysis: a review

People with low glomerular filtration rate and people on dialysis are spontaneously at risk for vitamin deficiency because of the potential for problems with decreased appetite and decreased sense of smell and taste, leading to decreased intake, and because decreased energy or decreased cognitive ability results in difficulties in shopping and cooking. Imposed dietary restrictions because of their renal dysfunction and because of comorbidities such as hypertension and diabetes exacerbate this problem. Finally, particularly for water-soluble vitamins, loss may occur into the dialysate. We did not identify any randomized trials of administering daily doses close to the recommended daily allowances of these vitamins. In people who are eating at all, deficiencies of B5 and B7 seem unlikely. It is unclear whether supplements of B2 and B3 are necessary. Because of dialyzability and documented evidence of insufficiency in dialysis patients, B1 supplementation is likely to be helpful. B6, B9, and B12 are implicated in the hyperhomocysteinemia observed in patients on dialysis. These vitamins have been studied in combinations, in high doses, with the hope of reducing cardiovascular outcomes. No reductions in patient-important outcomes were seen in adequately powered randomized trials. Because of their involvement in the homocysteine pathway, however, supplementation with lower doses, close to the recommended daily allowances, may be helpful. Vitamin C deficiency is common in patients on dialysis who are not taking supplements: low-dose supplements are warranted. Vitamins for dialysis patients contain most or all of the B vitamins and low-dose vitamin C. We are not aware of any medical reasons to choose one over another.

Effect of short-term intravenous ascorbic acid on reducing ferritin in hemodialysis patients

Resistance to recombinant erythropoietin (rEPO) in hemodialysis patients may be due to inadequate iron recruitment and defect in iron use. In this cross over randomized clinical trial, 30 hemodialysis patients with serum ferritin levels of ≥500 ng/ml, hemoglobin ≤11.0 g/dl, and transferrin saturation (TSAT) of 20% or less were administrated intravenous iron (50-100 mg/wk) and rEPO (120-360 U/kg/wk) for 6 months. Patients were excluded if there was a clear explanation for rEPO hyporesponsiveness. Patients were divided into two groups. Group1 received standard care and 500 mg of intravenous ascorbic acid (IVAA) with each dialysis session in the first week of each month for a total of 3 months. Group 2 received standard care only. After 2 month washout period, groups were crossed over. Each month hemoglobin (Hb) was assessed. Iron, TIBC (transferrin iron binding capacity), TSAT, iPTH (intact parathyroid hormone), liver enzymes, albumin and cholesterol levels were measured every 3 months. After 3 months of intervention, Hb significantly increased from 10.11 to 12.19 g/dl (P <0 0.001; 95% confidence interval [CI] 2.7-1.4) and TSAT increased from 18.9 to 28.1% (P = 0.008; 95% CI 0.09-3), while ferritin and serum iron declined significantly from 1391 to 938 ng/ml (P = 0.001; 95% CI 216-689), 97.2 to 64.6 (P = 0.001; 95% CI 14.8-50.4) in the study group. Change of Hb over time in IVAA group was significant (P < 0.0005). There were significant differences between two groups in change of Hb level over time (P < 0.0005) and treatment effect (P = 0.002). Baseline laboratory tests were similar in the two groups and there was no carry over effect at phase 2. We showed that low amount of IVAA could reduce ferritin level and enhance Hb and TSAT, suggesting improved iron utilization.

Vitamin C affects the expression of hepcidin and erythropoietin receptor in HepG2 cells

BACKGROUNDS

Hepcidin modulates the de novo absorption of iron from the duodenum and the recycling of iron released from the reticuloendothelial system. In patients with chronic renal failure, administration of higher doses of erythropoietin (EPO) or vitamin C (Vit C) can correct the functional iron deficiency. While EPO-regulated hepcidin expression within hepatocytes has been recently identified, the relation between vitamin C with hepcidin expression is still uncertain.

METHODS

Hepcidin-producing HepG2 cells (a human liver carcinoma cell line) were cultured with 50- to 100-μg/mL vitamin C or 0.25- to 1.0-U/mL EPO for 6 hours. Reverse transcription polymerase chain reaction was performed for quantitative measurements of hepcidin, EPO, and EPO receptor (EPOR) expression.

RESULTS

EPO and vitamin C inhibited hepcidin expression within HepG2 cells; the EPO effect was dose dependent. EPO downregulated EPOR and vitamin C and upregulated EPOR. However, vitamin C had little effect on the expression of EPO.

CONCLUSIONS

EPO is capable of downregulating EPOR when it acts early. Vitamin C directly inhibits hepcidin expression within HepG2 cells. Moreover, by enhancing EPOR production, vitamin C may correct the downregulating EPOR from EPO, which has additional effect with EPO in treating anemia.

Oral manifestations of hematologic and nutritional diseases

Oral manifestations of hematologic and nutritional deficiencies can affect the mucous membranes, teeth, periodontal tissues, salivary glands, and perioral skin. This article reviews common oral manifestations of hematologic conditions starting with disorders of the white blood cells including cyclic hematopoiesis (cyclic neutropenia), leukemias, lymphomas, plasma cell dyscrasias, and mast cell disorders; this is followed by a discussion of the impact of red blood cell disorders including anemias and less common red blood cell dyscrasias (sickle cell disease, hemochromatosis, and congenital erythropoietic porphyria) as well as thrombocytopenia. Several nutritional deficiencies exhibit oral manifestations. The authors specifically discuss the impact of water-soluble vitamins (B2, B3, B6, B9, B12, and C), fat-soluble vitamins (A, D, and K) and the eating disorders anorexia nervosa and bulimia nervosa on the oral mucosa.