Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Optimizing the use of recombinant human erythropoietin (r-HuEPO) involves choosing an appropriate dose regimen and target haemoglobin level, addressing factors that inhibit response, and considering appropriate adjuvant therapy. Subcutaneous administration of r-HuEPO two or three times weekly is optimal for most patients. Early detection and treatment of iron deficiency is mandatory. Measurement of the percentage of hypochromic red blood cells is a reliable marker of functional iron deficiency, and the treatment of choice is intravenous iron. Other factors that can affect the response to r-HuEPO include blood loss (sometimes occult), infection, inflammation, hyperparathyroidism with marrow fibrosis, aluminium toxicity, vitamin B12/folate deficiency, haemolysis, bone marrow disorders, haemoglobinopathies, under-dialysis and possibly angiotensin-converting enzyme inhibitors. These factors should be identified and corrected where possible. Ascorbic acid, vitamin D, folic acid, carnitine, other cytokines and growth factors have all been shown to augment the response to r-HuEPO in some patients. Further research is required before any of these adjuvant therapies can be incorporated into routine clinical practice. With regard to target haemoglobin value, the current practice is to aim for a level of 10-12 g/dl, but it may be argued that a higher target would achieve greater benefits in terms of physical performance, quality of life, and possibly cardiac morbidity and mortality. International multicentre trials are currently in progress to address this issue, as are studies on other substances that may be able to stimulate erythropoiesis.
Nephrol Dial Transplant 1998
PMID:Meeting the challenges of a new millennium: optimizing the use of recombinant human erythropoietin. 1048 48

Anaemia is a common problem in patients with renal failure, whether or not they are on dialysis. There is a continuum of declining renal function. In addition, the creatinine clearance at which dialysis is initiated varies widely between institutions and between studies. The term 'progressive renal insufficiency' is therefore preferable to 'pre-dialysis'. The adverse effects of renal anaemia on left ventricular mass become apparent early in the course of progressive renal insufficiency; 75% of patients starting dialysis already have left ventricular hypertrophy (LVH). Correction of anaemia in patients with progressive renal insufficiency has been shown to improve physical function and anaemia-related symptoms, but no controlled studies have yet been conducted to determine its effects on LVH. Although one animal study generated some concern that epoetin may exacerbate a decline in renal function, there is no evidence from human studies for any such effect. Treatment of anaemia with epoetin in anaemic patients with progressive renal insufficiency is therefore recommended, provided blood pressure is controlled. To date, however, there are insufficient data to determine whether normalization of haemoglobin is advisable in this patient group. Detection and correction of iron deficiency is important to achieve the full benefits of epoetin, though recommendations cannot yet be made regarding the optimum route and timing of iron supplementation in patients with progressive renal insufficiency. In these patients the role of other adjuvant therapies, such as L-carnitine, vitamin B6, vitamin B12 and folic acid, also requires further investigation.
Nephrol Dial Transplant 1999
PMID:How should anaemia be managed in pre-dialysis patients? 1033 70

Impaired erythropoiesis in continuous ambulatory peritoneal dialysis (CAPD) or continuous cyclic peritoneal dialysis (CCPD) patients receiving recombinant human erythropoietin (rHuEPO) is most often secondary to iron deficiency, either as a result of poor intestinal absorption or failure to take oral supplements as prescribed. The inconvenience of giving intravenous (i.v.) iron dextran (ID) to CAPD/CCPD patients precluded its use in this population. We therefore examined the efficacy of bolus intraperitoneal (i.p.) iron dextran (1000 mg) on erythropoiesis in a pilot study of 14 CAPD/CCPD patients. The patients ranged in age from 23-81 years, and all had iron deficiency (transferrin saturation 6%-23%; mean: 15.2% +/- 1.34%). Of the 14 patients studied, 13 were receiving rHuEPO. Pre-treatment hematocrit (Hct) ranged from 21%-38% (mean: 30.2% +/- 1.37%). After infusion of 2 L Dianeal (Baxter Healthcare Corp., Deerfield, Illinois, U.S.A.), 500 mg of undiluted ID was administered directly into the Tenckhoff catheter and subsequently flushed with 30 mm3 normal saline. The peritoneal dialysis (PD) exchange containing ID then dwelled for a period not < 6 hours before standard PD resumed. A second 500 mg dose ID was given to each patient by the same protocol 3-86 days later (mean: 14 days). No complications were seen. No patient complained of abdominal pain or other subjective symptoms during infusion or during the dwell. Repeat iron studies done 1-7 months post ID (mean: 2.8 months) showed a 1.1-fold to 4.9-fold increase (mean: 1.4-fold) in mean iron levels (40.4 +/- 3.9 mg/dL versus 57.5 +/- 5.5 mg/dL, p = 0.036); a 1.1-fold to 5.2-fold increase (mean: 1.6-fold) in mean transferrin saturation (15.2% +/- 1.3% versus 24.5% +/- 2.6%, p = 0.008); a 1.01-fold to 1.60-fold increase (mean: 1.12-fold) in mean Hct (30.2% +/- 1.37% versus 33.8% +/- 1.5%; p = 0.042). The mean dose of rHuEPO was statistically unchanged (170.0 +/- 47.4 U/kg body weight versus 178.8 +/- 49.6 U/kg body weight per week; p = 0.841). Peritoneal equilibration test (PET) score 1-4 months post ID (mean: 2 months) was 0.778 +/- 0.02 compared with a PET score at baseline of 0.767 +/- 0.03 (p = 0.734). No significant delta was observed in blood urea nitrogen (BUN) or creatinine values. We conclude that use of bolus i.p. ID is safe, effective, and convenient, and demonstrates no short-term negative effect on peritoneal membrane integrity. Long-term effects have yet to be determined.
Adv Perit Dial 1999
PMID:Use of bolus intraperitoneal iron dextran in continuous ambulatory peritoneal dialysis or continuous cyclic peritoneal dialysis patients receiving recombinant human erythropoietin. 1068 73

Effective management of early anaemia in the course of chronic renal insufficiency requires the following: (i) implementing an efficient diagnostic strategy to exclude common contributing factors; (ii) initiating epoetin therapy for the majority of patients; for and (iii) ensuring adequate iron supply erythropoiesis. Diagnostic inquiry is warranted whenever the haemoglobin concentration is below the normal range adjusted for age and gender. The most efficient diagnostic approach is to assume erythropoietin deficiency, exclude iron deficiency, and pursue further diagnostic tests only when red-cell indices are abnormal or when leukopenia or thrombocytopenia are also present. Macrocytosis should prompt an inquiry into alcoholism, B12 deficiency, or folate deficiency. Microcytosis suggests iron deficiency or thalassaemia. Associated cytopenias raise the possibility of alcohol toxicity, pernicious anaemia, malignancy, or myelodysplastic syndrome. Epoetin therapy is warranted whenever the haemoglobin concentration has fallen below 10.0 g/dl. To initiate therapy prior to dialysis, epoetin should be administered at an average dose of 100 IU/kg/week (80-120 IU/kg/week, 50-150 IU/kg/ week) by subcutaneous injection. Haemoglobin concentration should be monitored every 2 weeks and the epoetin dose adjusted by increments or decrements of 25% to maintain a rate of rise of haemoglobin concentration of 0.2-0.6 g/dl (0.3 0.6 g/dl/week, 0.2-0.5 g/dl/week). When the target range is achieved, the dose of epoetin should be continually adjusted to maintain a stable haemoglobin concentration. Transferrin saturation and ferritin concentration should be monitored monthly, and sufficient iron provided to maintain transferrin saturation above 20%. The lower the haemoglobin concentration, the greater the likelihood that future intravenous iron will be required. Oral iron supplements should be avoided, since they are costly, ineffective, and troublesome to patients. Finally, a blunted therapeutic response to epoetin therapy provides important diagnostic information and gnostic inquiry.
Nephrol Dial Transplant 2000
PMID:Management of early renal anaemia: diagnostic work-up, iron therapy, epoetin therapy. 1103 56

Provision of sufficient available iron is a prerequisite to ensure the optimal response to recombinant human erythropoietin (rHuEpo). Functional iron deficiency (a state when iron supply is reduced to meet the demands for increased erythropoiesis) is the common cause of rHuEpo hyporesponsiveness in dialysis patients who have normal iron status, even when they are iron-overloaded. Iron supplementation is not justified for this hyporesponsiveness in patients with iron overload due to the potential hazards of iron overload aggravated by intravenous iron therapy. Furthermore, in vivo studies indicated that the promising effect of intravenous iron medication to overcome iron-deficient erythropoiesis is not observed in iron-overloaded haemodialysis (HD) patients. Ascorbic acid, a water-soluble antioxidant as well as a reducing agent, has a number of associations with iron metabolism. Recent research highlights that ascorbic acid can potentiate the mobilization of iron from inert tissue stores and facilitates the incorporation of iron into protoporphyrin in iron-overloaded HD patients being treated with rHuEpo. Interest has turned towards the use of ascorbic acid as an adjuvant therapy in this field. This review focuses on the improvement of rHuEpo response by administration of ascorbic acid and discusses its clinical implications and potential issues for nephrologists.
Nephrol Dial Transplant 2001
PMID:Erythropoietin and iron: the role of ascorbic acid. 1150 82

The invention of recombinant human erythropoietin (rHuEpo) for the treatment of renal anaemia was a hallmark in the care of patients with renal insufficiency. Recently published guidelines (European Best Practice Guidelines, NKF-DOQI) have set the target haemoglobin to be reached by treatment with rHuEpo to >11 g/dl. Normalizing haemoglobin levels may reduce morbidity and mortality and improve quality of life in haemodialysis patients. During long-term treatment, most patients will not respond adequately to therapy with rHuEpo alone. The most important confounding factor, limiting the effectiveness of rHuEpo, is absolute or functional iron deficiency, which is now recognized and treated in many dialysis units. However, there are several other adjuvant treatment options which may help to optimize the response to treatment with rHuEpo. A weekly dose of 2-3 mg of folic acid and 100-150 mg of vitamin B6 is recommended for haemodialysis patients on rHuEpo therapy. The addition of 0.25 mg/month of vitamin B12 may be necessary in selected patients. Vitamin C (1-1.5 g/week) was shown to overcome functional iron deficiency in patients with high ferritin levels. The potential increase of oxidative stress induced by intravenous iron therapy may be blunted by concomitant administration of vitamin E (1200 IU). There is clear evidence from the literature that treatment of secondary hyperparathyroidism by vitamin D improves erythropoiesis. The most recently discovered biological effects of rHuEpo include the induction of several genes in endothelial cells as well as a role for erythropoietin in the outcome of plasmodium infection. A new erythropoietin-like molecule is novel erythropoiesis stimulating protein (NESP), which is as effective and safe as rHuEpo, with the potential advantage of less frequent dosing.
Nephrol Dial Transplant 2001
PMID:Novel aspects of erythropoietin response in renal failure patients. 1150 83

Recombinant human erythropoietin therapy has transformed the management of renal anaemia over the last decade or so. We have learned much about the optimum regimens for using this drug, including the route of administration, dosage frequency, use of iron supplementation, and management of poor response. Thus, dosage requirements of epoetin are generally lower if the drug is administered subcutaneously, and the most commonly used dosage frequency is two or three times weekly. The vast majority of patients respond very well to treatment, but approximately 5-10% of patients show some resistance to epoetin, the most common cause of which is iron deficiency. The presence of infection or inflammation and underdialysis are other important causes of a poor response to epoetin. There is increasing interest in treating renal anaemia at an earlier stage in the course of the disease, and there is much circumstantial evidence to support this strategy. This usually involves giving epoetin to pre-dialysis patients, and a study has also recently commenced to investigate the effects of preventing renal anaemia ever developing. Other erythropoietic substances are being developed, and the first of these to be ready for clinical use is novel erythropoiesis stimulating protein (NESP), which is an analogue of erythropoietin containing two extra N-linked carbohydrate side-chains. Other potential erythropoietic substances are still at the laboratory stage of development, but may be available for therapeutic use in the next decade or so.
Nephrol Dial Transplant 2001
PMID:Present and future strategies in the treatment of renal anaemia. 1150 85

The introduction of recombinant human erythropoietin (rh-Epo, epoetin) as a treatment for the anaemia of renal failure has transformed the management of this condition. Nevertheless, a significant number of patients fail to respond. There are many different possible causes of inadequate response to epoetin. Iron deficiency, whether absolute or functional, is considered to be the most important, and it is widely accepted that maintaining adequate iron levels reduces rh-Epo dosage requirement and improves efficacy in haemodialysis patients. Infection and inflammation have been shown to influence responsiveness to rh-Epo by disrupting iron metabolism and eliciting the release of cytokines that inhibit erythropoiesis. Another factor for consideration is severe hyperparathyroidism, which can lead to a reduced number of responsive erythroid progenitor cells. Inadequate dialysis can also negatively impact on rh-Epo therapy, and aluminium overload interferes with iron metabolism and reduces the efficacy of rh-Epo. Deficiencies in vitamin B(12), folic acid and potentially vitamin C can all reduce the efficacy of treatment with rh-Epo. Optimizing patient response to rh-Epo therapy, therefore, requires consideration of many factors, some well established and others that are more controversial, and the list continues to grow with the identification of new factors.
Nephrol Dial Transplant 2001
PMID:Hyporesponsiveness to recombinant human erythropoietin. 1159 Feb 53

Although iron deficiency is probably the most important factor affecting response to recombinant erythropoietin (Epo, epoetin), other factors are of significance, including dialysis adequacy. Additionally, water treatment and distribution, sterilizants and the quality of the dialysate in terms of trace elements (particularly chloramine) are of importance in relation to erythropoiesis inhibition. Microbiological or pyrogenic contamination can cause or aggravate anaemia in haemodialysis patients, and the impact of enhanced production of cytokines should be taken into consideration. By removing small and (possibly) medium/large molecules, adequate dialysis is of paramount importance in correcting anaemia and optimizing epoetin therapy. The biocompatibility of dialysis membranes and flux are other important factors. As yet unknown uraemic toxins may suppress erythropoiesis and contribute towards the development of anaemia. It is reasonable to hypothesize that, because anaemia improves after the start of dialysis with cellulose membranes, low molecular weight erythropoiesis inhibitors are involved, as well as medium/large molecular weight inhibitors, which are removed by more permeable membranes. However, in highly selected, adequately dialysed patients without iron or vitamin depletion, the effects of dialysis membrane type on haematological parameters and epoetin efficacy are smaller than might be expected from the results of uncontrolled studies. Improvement in anaemia has been observed using on-line haemofiltration, haemodiafiltration, and sterile dialysate. The results of prospective, randomized trials examining the impact of these factors on anaemia and the effectiveness of epoetin treatment are eagerly awaited.
Nephrol Dial Transplant 2001
PMID:Dialysis: its role in optimizing recombinant erythropoietin treatment. 1159 Feb 54

Patients receiving epoetin therapy show wide variability in their responsiveness to the drug. Many factors may be responsible for this, particularly iron deficiency, acute infection and under-dialysis. Even after excluding factors known to cause resistance to epoetin, the marked variability in sensitivity to epoetin remains. The exact mechanism of this effect is unclear. It is, however, recognized that uraemia is a chronic inflammatory state, with some patients showing quite significantly increased laboratory markers of inflammation and immune activation. It is also known that chronic inflammation can modify the process of erythropoiesis, and this is probably mediated via pro-inflammatory cytokines such as interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). It is hypothesized, therefore, that some patients showing resistance to epoetin may have enhanced levels of immune activation, causing increased release of pro-inflammatory cytokines in the bone marrow. This has been investigated by studying T-cell phenotypes by flow cytometry, along with cytokine release from T cells and monocytes in 'good' and 'poor' responders to epoetin. Poor responders were found to have significantly reduced CD28 expression on both CD4(+) and CD8(+) cells, enhanced IL-10 generation from peripheral blood mononuclear cells (PBMCs), higher plasma IL-12 levels and enhanced TNF-alpha release from PBMCs. The patients in this study, who were followed-up for the subsequent 24 months, had a considerably lower survival if they were poor responders (54% vs 88% for good responders; P<0.05). Further work in this area is required to confirm or contest the hypothesis that epoetin resistance is due to enhanced levels of immune activation.
Nephrol Dial Transplant 2002
PMID:The inflammatory response and epoetin sensitivity. 1181 13


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