Pharmacologic adjuvants to epoetin in the treatment of anemia in patients on hemodialysis

Role of Intravenous Ascorbic Acid in the Management of Anemia in Hemodialysis Patients

Introduction:

Patients with end-stage kidney disease (ESKD) suffer from functional iron deficiency where despite the presence of sufficient iron stores in the body, adequate iron is unavailable for heme synthesis. This study hypothesis was that in patients undergoing hemodialysis (HD), administration of intravenous (IV) ascorbic acid (AA) exerts a good effect on the management of anemia, either by increasing the mobilization of iron from tissue stores or acting as an antioxidant to overcome the inflammatory block and increase the erythropoietin sensitivity.

Methods:

Fifty patients with ESRD who were on regular HD were included in the study. Patients' ferritin levels ranged from 500 to 1200 ng/mL with transferrin saturation of 30% or more. However, all patients were anemic and received erythropoietin therapy. Iron therapy was discontinued in the first group, whereas it was continued in the second group that received IV AA.

Results:

A significant increase in the levels of Hb was observed in the second group after 6 months despite the decrease in ferritin levels in both the groups. Transferrin saturation decreased in both groups, the decrease being more in the first group. The levels of C-reactive protein (CRP) decreased in the second group, whereas these increased in the first group.

Conclusions:

Intravenous AA as an adjuvant therapy with iron exerts a favorable and significant effect on the Hb, serum ferritin, and CRP levels in patients with ESKD having anemia. The discontinuation of iron therapy only decreases the serum ferritin levels and does not improve the Hb or CRP levels.

Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement

L-histidine (HIS) is an essential amino acid with unique roles in proton buffering, metal ion chelation, scavenging of reactive oxygen and nitrogen species, erythropoiesis, and the histaminergic system. Several HIS-rich proteins (e.g., haemoproteins, HIS-rich glycoproteins, histatins, HIS-rich calcium-binding protein, and filaggrin), HIS-containing dipeptides (particularly carnosine), and methyl- and sulphur-containing derivatives of HIS (3-methylhistidine, 1-methylhistidine, and ergothioneine) have specific functions. The unique chemical properties and physiological functions are the basis of the theoretical rationale to suggest HIS supplementation in a wide range of conditions. Several decades of experience have confirmed the effectiveness of HIS as a component of solutions used for organ preservation and myocardial protection in cardiac surgery. Further studies are needed to elucidate the effects of HIS supplementation on neurological disorders, atopic dermatitis, metabolic syndrome, diabetes, uraemic anaemia, ulcers, inflammatory bowel diseases, malignancies, and muscle performance during strenuous exercise. Signs of toxicity, mutagenic activity, and allergic reactions or peptic ulcers have not been reported, although HIS is a histamine precursor. Of concern should be findings of hepatic enlargement and increases in ammonia and glutamine and of decrease in branched-chain amino acids (valine, leucine, and isoleucine) in blood plasma indicating that HIS supplementation is inappropriate in patients with liver disease.

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.

Effect of uremia and hemodialysis on proteome profile of blood platelets and plasma

The aim of the present research was to assess the differences in blood platelet and plasma proteome profiles of patients with uremia in comparison with healthy participants. It was found that 23 peptides in the platelet proteome profiles of hemodialyzed patients and only 6 peptides in nondialyzed patients were upregulated. On the other hand, 18 peptides with reduced expression in nondialyzed patients and only 1 peptide in hemodialyzed patients were found. For serum, only 6 upregulated peptides in patients undergoing hemodialysis and 15 peptides in nondialyzed patients were found, most of these were about 10 kDa. A decrease in serum peptide expression was not observed. In conclusion, it should be noted that the process of hemodialysis modifies the platelet proteome to a greater extent than uremia alone, however the sera of nondialyzed patients have much larger amounts of low-molecular-weight peptides than those of hemodialyzed patients.

Effect of uremia and hemodialysis on platelet apoptosis

The blood platelet proteome of hemodialyzed patients with uremia exhibits significant difference in comparison with the blood platelet proteome of healthy individuals. This alteration is manifested by the presence of high concentrations of low-molecular peptides within the whole range of isoelectric points. Increased platelet apoptosis has been put forward as a possible cause of this phenomenon. The aim of the present research was to assess whether blood platelet populations from hemodialyzed patients with uremia exhibit higher binding capacity of Annexin V than control samples from healthy donors. It was found that blood platelets of hemodialyzed patients, in the period between dialyses, bound significantly more Annexin V with no different incorporation of propidium iodide in comparison with platelets of control donors and conservatively treated patients with uremia. The results support the hypothesis that the process of hemodialysis may be at least partially responsible for triggering blood platelet apoptosis and result in increased risk of thrombosis.

The blood platelet proteome is changed in UREMIC patients

Comparative analysis of the protein profile of blood platelets isolated from nondialyzed and hemodialyzed uremic patients and healthy controls has been performed. These preliminary results indicate markedly changed expression of several proteins in blood platelets from both groups of patients compared with controls, with dramatic changes in hemodialyzed patients in the over-expression of low molecular peptides with a very wide range of pI values.

Endogenous plasma carnitine pool composition and response to erythropoietin treatment in chronic haemodialysis patients

BACKGROUND

Anaemia is a common complication associated with haemodialysis and is usually managed by treatment with recombinant human erythropoietin (rHuEPO). However, many patients remain hyporesponsive to rHuEPO treatment despite adequate iron therapy. The effect of L-carnitine administration on rHuEPO dose and/or haematocrit in haemodialysis patients has been previously reported with equivocal results. This study examined the relationship between endogenous carnitine pool composition and rHuEPO requirements in long-term haemodialysis patients.

METHODS

Pre-dialysis blood samples were collected from 87 patients and analysed for plasma L-carnitine and individual acylcarnitine levels by LCMS/MS. As an indication of rHuEPO responsiveness, erythropoietin resistance index (ERI) was calculated as rHuEPO dose/kg/week normalized for haemoglobin levels.

RESULTS

A significant negative correlation between L-carnitine levels and ERI was found (P = 0.0421). All patients categorized as high ERI (>0.02 microg/kg/week/gHb) exhibited subnormal L-carnitine levels (<30 microM); conversely, patients with normal L-carnitine levels (>30 microM) displayed low ERI values (<0.02 microg/kg/week/gHb). More importantly, the ratio of non-acetyl acylcarnitines/total carnitine was significantly positively correlated with ERI (P = 0.0062).

CONCLUSIONS

These data illustrate the relationship between carnitine levels and response to rHuEPO treatment in haemodialysis patients, in particular, the importance of the proportion of long-chain acylcarnitines within the plasma carnitine pool. This proportion may be more indicative of the response to L-carnitine supplementation than absolute L-carnitine levels alone.