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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CHF is highly prevalent in ESRD and is a leading cause of death in such patients. Hypertension, renal anemia, and comorbid conditions such as coronary artery disease are particularly important risk factors for CHF in ESRD. Dialysis hypotension may be a marker of poor prognosis in such persons. Recent studies suggest that lipid peroxidation and L-carnitine deficiency may contribute to CHF in some patients with ESRD. All forms of renal replacement therapy are capable of ameliorating symptoms of CHF, but their effect on cardiovascular mortality has not been firmly established. Drug therapy, particularly angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers, is under-used in patients with ESRD and CHF. Heart/kidney transplantation may be a viable option for some patients with advanced CHF and ESRD.
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PMID:Congestive heart failure in patients with chronic kidney disease and on dialysis. 1269 23

Careful review of all available clinical trials of L-carnitine leads to the conclusion that there is insufficient evidence to support the routine use of L-carnitine for any indication in dialysis patients. The literature suffers from a lack of adequately designed studies, and many of the studies which supposedly justify payment for L-carnitine supplementation are more than 10 years old. While some studies support a subjective improvement in symptoms after a few months of L-carnitine treatment, there is little confirming objective data. Biochemical parameters show minimal, if any, improvements. A major criticism is that many of the reported symptoms could be attributable to anemia, which at the time the L-carnitine studies were taking place, was generally being corrected with EPO. On the other hand, there is little data to support the hypothesis that L-carnitine enhances the response to EPO or overcomes EPO resistance. The decrease in the use of L-carnitine in the past several years may be related in part to difficulty with reimbursement. The decrease also suggests that practitioners have abandoned the hypothesis that L-carnitine supplementation provides substantial clinical benefits, and therefore no longer prescribe it for dialysis patients. For those physicians who plan to prescribe L-carnitine based on the recent CMS reimbursement decision, it must be remembered that the laboratory measurement of free carnitine may be difficult and inaccurate. For those patients with private insurance, payment for the lab test is out of pocket. If the free carnitine level is measured once dialysis starts, a value in the CMS "deficient" range can occur since carnitine drops early in the dialysis procedure and slowly rebounds after the treatment. Therefore, it is critical that the measurement be done pre-dialysis after a three-day interdialytic interval to obtain the most accurate value. If strict guidelines for use of L-carnitine are adhered to (i.e., the patient has true EPO-resistant anemia unexplained by any identifiable factor and true unexplained hypotension), then the use of L-carnitine in ESRD patients should be very uncommon. In conclusion, the clinical value of L-carnitine supplementation in hemodialysis patients remains to be documented by credible evidence from rigorous scientific studies. While "proof beyond a reasonable doubt" need not always be the requirement for reimbursement from payers, at a minimum "a preponderance of the evidence" should be documented in the literature. L-carnitine may prove to be a beneficial supplement. However, before justifying a national coverage policy, a new randomized, prospective controlled trial should be conducted to determine the utility of i.v. L-carnitine supplementation for anemia management and refractory dialysis-associated hypotension. Cost-benefit analysis is a critical aspect of such a study because it is important to determine the total cost (no matter who pays) of L-carnitine supplementation as compared to money saved by a reduction in EPO and iron administration. When reimbursement policies are developed, they need to be rational and based on the best evidence that is available. An NKF Carnitine Consensus Conference concluded that current literature and clinical experience leave unanswered questions regarding the use of L-carnitine in dialysis patients. Until there is scientific evidence to support use of L-carnitine supplementation, and it proves to be cost-effective, reimbursement is not justified. Therefore, the current CMS reimbursement decision for L-carnitine appears to be flawed.
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PMID:L-carnitine use in dialysis patients: is national coverage for supplementation justified? What were CMS regulators thinking--or were they? 1284 56

Among the homeostatic processes controlling the endogenous L-carnitine pool in humans, the kidney has a vital role through extensive and adaptive tubular reabsorption. Kidney disease can lead to disturbances in L-carnitine homeostasis, and long-term hemodialysis therapy can lead to a significant reduction in plasma and tissue L-carnitine levels and an increase in the ratio of acyl-L-carnitine to free L-carnitine. These alterations may interfere with the oxidation of fatty acids and removal from tissues of unwanted short-chain acyl groups. A dialysis-related carnitine disorder (DCD) arises when these biochemical abnormalities exist in association with such clinical symptoms as muscle weakness, cardiomyopathy, intradialytic hypotension, or anemia that is resistant to erythropoietin therapy. Exogenous L-carnitine, administered intravenously, is approved for the treatment of secondary carnitine deficiency caused by long-term hemodialysis. Although intravenous administration of 20-mg/kg doses at the end of each hemodialysis session leads to supraphysiological levels of the compound in plasma, these levels do not appear to be associated with adverse effects. Because more than 99% of the body's carnitine pool is located outside of plasma, supraphysiological plasma levels appear to be required to ensure that depleted muscle stores can be replenished. Although oral L-carnitine has been used for the treatment of DCD, the bioavailability of oral L-carnitine is low (<15%) in healthy subjects and unknown in patients with end-stage renal disease. Moreover, gastrointestinal degradation of L-carnitine to trimethylamine and other compounds might limit the usefulness of long-term oral L-carnitine administration in this patient group.
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PMID:Dialysis-related carnitine disorder and levocarnitine pharmacology. 1275 Oct 50

Recombinant human erythropoietin (rHuEPO) and iron supplementation have had a profoundly positive impact on the anemia of patients with chronic kidney disease. However, a significant number of patients remain hyporesponsive to rHuEPO, with hemoglobin values less than target levels. A suboptimal response to rHuEPO is associated with complications that can reduce quality of life and increase morbidity, mortality, and costs. There are a number of other metabolic derangements associated with uremia that can impact on the production and survival of red blood cells. Dialysis-related carnitine disorder is a functional metabolic deficiency, common in chronic dialysis patients, that can have a negative impact on erythrocyte production and survival. This article reviews the role of L-carnitine in the pathogenesis and adjunctive treatment of anemia associated with kidney failure. After a comprehensive database search, primary and secondary reports were analyzed. Laboratory studies examining the influence of carnitine on red blood cell function and clinical trials of L-carnitine in dialysis patients support the use of L-carnitine in the setting of rHuEPO hyporesponsiveness. Consensus groups, including the National Kidney Foundation-Kidney Disease Outcome Quality Initiative (K/DOQI), consider the use of L-carnitine for hyporesponsive rHuEPO-dependent anemia a promising application of this therapy, recommending an empiric trial of L-carnitine in these patients.
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PMID:L-carnitine treatment of anemia. 1275 Oct 51

Carnitine is an ammo acid derivative found in high energy demanding tissues (skeletal muscles, myocardium, the liver and the suprarenal glands). It is essential for the intermediary metabolism of fatty acids. Carnitine is indispensable for beta-oxidation of long-chain fatty acids in the mitochondria but also regulates CoA concentration and removal of the produced acyl groups. AcylCoAs act as restraining factor for several enzymes participating in intermediary metabolism. Transformation of AcylCoA into acylcarnitine is an important system for removing the toxic acyl groups. Although primary deficiency is unusual, depletion due to secondary causes, such as a disease or a medication side effect, can occur. Primary carnitine deficiency is caused by a defect in plasma membrane carnitine transporter in muscle and kidneys. Secondary carnitine deficiency is associated with several inborn errors of metabolism and acquired medical or iatrogenic conditions, for example in patients under valproate and zidovuline treatment. In cirrhosis and chronic renal failure, carnitine biosynthesis is impaired or carnitine is lost during hemodialysis. Other chronic conditions like diabetes mellitus, heart failure, Alzheimer disease may cause carnitine deficiency also observed in conditions with increased catabolism as in critical illness. Preterm neonates develop carnitine deficiency due to impaired proximal renal tubule carnitine re-absorption and immature carnitine biosynthesis. Carnitine stabilizes the cellular membrane and raises red blood cell osmotic resistance but has no metabolic influence on lipids in dialysis patients. L-Carnitine has been administered in senile dementia, metabolic nerve diseases, in HIV infection, tuberculosis, myopathies, cardiomyopathies, renal failure anemia and included in baby foods and milk.
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PMID:Carnitine metabolism and deficit--when supplementation is necessary? 1276 64

Possible potentiation of the immunomodulating effects of carbohydrate and lipid metabolism regulators by their use in combination with polyunsaturated phospholipids was studied. The polyunsaturated phospholipids in toxic anemia icreased the immunomodulating effects of thiamine and inosine which activated glucose catabolism in erythrocytes. The combined use of the polyunsaturated phospholipids and thiamine normalized the oxidation--energy status and lowered manifestation of the immunosuppressing properties of light erythrocytes in laboratory rats exposed to hemolytic poison. The use of the combination of the polyunsaturated phospholipids and inosine normalized the oxidation--energy status and induced manifestation of the immunomodulating properties in heavy erythrocytes of the poisoned rats. The globulin fraction of the rat serum containing antibodies to erythrocytes of the poisoned rats exposed to the polyunsaturated phospholipids and inosine increased the immunity status of the poisoned rats treated with the above mentioned agents. Carnitine and biotin in combination with the polyunsatured phospholipids showed no effect on the phagocytic and metabolic activity of leukocytes and the immunity status of the rats exposed to hemolytic poison.
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PMID:[Immunomodulating activity of polyunsaturated phospholipids and regulators of energy metabolism in toxic anemia]. 1557 96

In patients with chronic renal failure, not yet undergoing hemodialysis (HD), plasma acylcarnitines accumulate in part due to a decreased renal clearance of esterified carnitine moieties. In these patients, a high acylcarnitine/free-carnitine ratio is usually found in plasma. Patients undergoing maintenance HD, usually present with plasma carnitine insufficiency, due to accumulation of metabolic intermediates combined with impaired carnitine biosynthesis, reduced protein intake and increased removal via HD. Plasma carnitine concentrations rapidly decrease to 40% of baseline level during the dialysis session, with a slow restoration of the carnitine concentration during the interdialytic period, mainly from organs of storage (skeletal muscle). Dietary intake also plays an important role in carnitine homeostasis of HD patients since the prevalence of malnutrition ranges from 18% to 75% of these cases. This could differentially affect various body compartments, with clinical consequences such as impaired muscle function, decreased wound healing, altered ventilatory response, and abnormal immune function. Repeated hemodialytic treatments are associated with decreased carnitine stores in skeletal muscle. The administration of intravenous L-carnitine (LC) postdialysis replenishes the free carnitine removed from the blood and contributes to replenishment of muscle carnitine content. LC supplementation in selected uremic patients may yield clinical benefits by ameliorating several conditions, such as erythropoietin-resistant anemia, decreased cardiac performance, intradialytic hypotension, muscle symptoms, as well as impaired exercise and functional capacities. Furthermore, LC may positively influence the nutritional status of HD patients by promoting a positive protein balance, and by reducing insulin resistance and chronic inflammation, possibly through an effect on leptin resistance.
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PMID:Carnitine replacement in end-stage renal disease and hemodialysis. 1559 Oct 3

The bioincompatibility of dialytic systems along with the loss of antioxidant substances via the dialysis may contribute to peripheral blood mononuclear cell (PBMC) activation and the production of inflammatory mediators, such as cytokines, oxygen radicals, and complement fragments, that may sustain a state of chronic microinflammation responsible for the pathogenesis of a variety of diseases, including atherosclerosis, anemia, and malnutrition. Moreover, during hemodialysis (HD), oxidative stress may influence several intracellular signaling enzymes, including some stress-activated kinases, such as jun-N-terminal kinase (JNK), potentially leading to PBMC activation and proinflammatory cytokine production. Recent reports suggest that L-carnitine may play an important role in balancing antioxidative systems. Therefore, we sought to evaluate the effect of L-carnitine supplementation on the PBMC responses to oxidative stress induced by different HD membranes. We observed in PBMC from cellulosic (C)-treated patients an increase in the amount of intracellular tyrosine-phosphorylated proteins and a striking activation of JNK, as compared with synthetic (S)-treated patients. On the contrary, 3 months of L-carnitine supplementation significantly lowered intracellular levels of phosphorylated proteins and JNK activity in PBMC from C-treated patients. In addition, after 180 minutes of HD, a significant decrease in global plasma antioxidant capacity was found, particularly in C-treated patients, whereas L-carnitine supplementation improved plasma antioxidant capacity levels in these patients. These observations were also confirmed by in vitro experiments, showing the ability of L-carnitine to reduce the JNK activation in normal PBMC exposed to different amounts of hydrogen peroxide. In conclusion, the uremic milieu is characterized by an enhanced inflammatory response and an increased oxidant load, affecting lipids, carbohydrates, and proteins. Regular L-carnitine supplementation in HD patients can improve cellular defense against chronic inflammation and oxidative stress, most likely by modulating the specific signal transduction cascade activated by an overproduction of proinflammatory cytokines and oxidative stress.
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PMID:Inflammation and carnitine in hemodialysis patients. 1564 99

Increased serum levels of C-reactive protein (CRP) in uremic and dialysis patients are associated with low serum prealbumin and albumin concentrations and increased mortality and greater risk of cardiovascular disease. Proinflammatory cytokines may cause malnutrition by increasing protein catabolism. Many studies have shown that L-carnitine supplementation leads to improvements in several conditions seen in uremic patients, including cardiac complications, impaired exercise and functional capacities, muscle symptoms, increased symptomatic intradialytic hypotension, and erythropoietin-resistant anemia. L-carnitine therapy may either suppress the inflammatory response or act independently on both inflammation and appetite and/or anabolic processes. Moreover, L-carnitine may suppress proinflammatory cytokines in sick individuals without renal disease and may improve protein synthesis or nitrogen balance in patients without renal disease and in hemodialysis and peritoneal dialysis patients. In a pilot study, we provided preliminary evidence that treatment with L-carnitine, 20 mg/kg 3 times weekly at the end of each hemodialysis treatment, was associated with a reduction in serum CRP levels and improvement in anabolic status. The improvement or normalization of serum concentrations of serum CRP also was correlated with increased serum concentrations of albumin, transferrin, and blood hemoglobin. The possibility that some or all of these changes may have been caused by improved nutritional intake cannot be ruled out. Further randomized clinical trials will be necessary to confirm the role of L-carnitine as a modulator of inflammatory protein synthesis in hemodialysis patients.
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PMID:Role of carnitine in modulating acute-phase protein synthesis in hemodialysis patients. 1564

Anemia is a common complication of chronic kidney disease, particularly in patients who are on dialysis. The use of recombinant human erythropoietin has led to the eradication of severe anemia in the dialysis population. Correction of anemia in these patients has been associated with better quality of life and clinical outcomes. Some hemodialysis patients have anemia that either is relatively refractory to epoetin therapy or requires very high doses of epoetin (i.e., hyporesponsiveness), despite having adequate iron stores, and are thus unable to achieve or maintain target hemoglobin levels. Several pharmacologic agents have been studied for effects on improving response to epoetin, either to counter hyporesponsiveness or simply to reduce epoetin use for purely economic reasons. This review examines the available literature regarding the efficacy of these potential pharmacologic adjuvants to epoetin in the treatment of anemia in patients on maintenance hemodialysis, with special emphasis on androgens, vitamin C (ascorbic acid), and L-carnitine. A review of published guidelines and recommendations for use of these agents in hemodialysis patients is provided.
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PMID:Pharmacologic adjuvants to epoetin in the treatment of anemia in patients on hemodialysis. 1619 Oct 49


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