Mechanisms of dyslipidemia of chronic renal failure

Effects of Oral L-Carnitine Supplementation on Lipid Profile, Anemia, and Quality of Life in Chronic Renal Disease Patients under Hemodialysis: A Randomized, Double-Blinded, Placebo-Controlled Trial

In patients on maintenance hemodialysis several factors reduce the body stored carnitine which could lead to dyslipidemia, anemia, and general health in these patients. We evaluated the effect of oral L-carnitine supplementation on lipid profiles, anemia, and quality of life (QOL) in hemodialysis patients. In a randomized, double-blinded, placebo-controlled trial, end-stage renal disease (ESRD) patients on hemodialysis received either L-carnitine 1 g/d (n = 24) or placebo (27 patients) for 16 weeks. At the end of the study, there was a significant decrease in triglyceride (-31.1 ± 38.7 mg/dL, P = 0.001) and a significant increase in HDL (3.7 ± 2.8 mg/dL, P < 0.001) levels in the carnitine group. Decrease in total cholesterol (-6.6 ± 16.0 mg/dL, P = 0.075) and increase in hemoglobin (0.7 ± 1.7 g/dL, P = 0.081) concentrations in the carnitine group were not significant. There was no statistically significant changes in LDL in any group (P > 0.05). Erythropoietin dose was significantly decreased in both the carnitine (-4750 ± 5772 mg, P = 0.001) and the placebo group (-2000 ± 4296 mg, P < 0.05). No improvement was observed in QOL scores of two groups. In ESRD patients under maintenance hemodialysis, oral L-carnitine supplementation may reduce triglyceride and cholesterol and increase HDL and hemoglobin and subsequently reduce needed erythropoietin dose without effect on QOL.

Dyslipidemia is a strong predictor of myocardial infarction in subjects with chronic kidney disease

AIM

To evaluate dyslipidemia as predictor of myocardial infarction (MI) in subjects with or without chronic kidney disease (CKD).

METHODS

In 142,394 middle-aged Swedes referred for laboratory evaluation, glomerular filtration rates (GFR) were estimated using the Modification of Diet in Renal Disease study equation. CKD was defined as GFR 15-60 mL/min/1.73 m(2). Subjects were stratified into presence or absence of CKD, and lipid measures were related to MI using Cox's proportional hazards regression.

RESULTS

During 12 years of follow-up there were 5,466 MIs. The adjusted hazard ratio for MI for the highest versus the lowest quartile of the apolipoprotein (apo) B/apoA-1 ratio among individuals without CKD was 2.88 (95% confidence interval 2.54-3.26) and for those with CKD 3.35 (2.25-4.91). The corresponding estimates for the total cholesterol/high-density lipoprotein (HDL) cholesterol ratio were 3.13 (2.78-3.52) and 3.54 (2.43-5.17), respectively. Receiver operator characteristics analyses showed an advantage in the prediction of MI for the apoB/apoA-1 ratio as compared to conventional lipids (P < 0.0001).

CONCLUSIONS

The ratio of apoB/apoA-1, the ratio of total cholesterol/HDL cholesterol, and non-HDL cholesterol were all strong predictors of myocardial infarction, both among subjects with and without renal dysfunction, with a possible advantage for the apoB/apoA-1 ratio.

Dyslipidemia associated with chronic kidney disease

Cardiovascular disease is a major cause of morbidity and mortality in patients with impaired renal function. Dyslipidemia has been established as a well-known traditional risk factor for cardiovascular disease (CVD) in the general population and it is well known that patients with chronic kidney disease (CKD) exhibit significant alterations in lipoprotein metabolism. In this review, the pathogenesis and treatment of CKD-induced dyslipidemia are discussed. Studies on lipid abnormalities in predialysis, hemodialysis and peritoneal dialysis patients are analyzed. In addition, the results of the studies that tested the effects of the hypolipidemic drugs on cardiovascular morbidity and mortality in patients with CKD are reported.

Early intervention strategies to lower cardiovascular risk in early nephropathy: focus on dyslipidemia

Patients with chronic kidney disease (CKD) are at high cardiovascular risk and we can consider them to have a risk equivalent to coronary heart disease, putting them into the high-risk category. A mixed dyslipidemia with high triglyceride levels; low high-density lipoprotein (HDL) levels; and small, dense low-density lipoprotein (LDL) particles is a common pattern in patients with CKD, contributing to their high cardiovascular disease (CVD) risk. A treatment strategy to reduce LDL cholesterol to the current high-risk category goals reduces risk similar to patients without CKD. Emerging evidence suggests that targeting non-HDL cholesterol can have the potential to bring about further CVD risk reduction. Non-HDL cholesterol should be a secondary target for all patients with CKD. Further studies are needed to determine the magnitude of the risk reduction we can expect to gain by targeting non-HDL cholesterol and the most effective way to treat this target.

Causes of dysregulation of lipid metabolism in chronic renal failure

End-stage renal disease (ESRD) is associated with accelerated atherosclerosis and premature death from cardiovascular disease. These events are driven by oxidative stress inflammation and lipid disorders. ESRD-induced lipid abnormalities primarily stem from dysregulation of high-density lipoprotein (HDL), triglyceride-rich lipoprotein metabolism, and oxidative modification of lipoproteins. In this context, production and plasma concentration of Apo-I and Apo-II are reduced, HDL maturation is impaired, HDL composition is altered, HDL antioxidant and anti-inflammatory functions are depressed, clearance of triglyceride-rich lipoproteins and their atherogenic remnants is impaired, their composition is altered, and their plasma concentration is elevated in ESRD. The associated defect in HDL maturation is largely caused by acquired lecithin-cholesterol acyltransferase deficiency while its triglyceride enrichment is due to hepatic lipase deficiency. Hypertriglyceridemia, abnormal composition, and impaired clearance of triglyceride-rich lipoproteins and their remnants are mediated by down-regulation of lipoprotein lipase, hepatic lipase, very low-density lipoprotein (VLDL) receptor, and LDL receptor-related protein, relative reduction in ApoC-II/ApoC-III ratio, up-regulation of acyl-CoA cholesterol acyltransferase, and elevated plasma level of cholesterol ester-poor prebeta HDL. Impaired clearance and accumulation of oxidation-prone VLDL and chylomicron remnants and abnormal LDL composition in the face of oxidative stress and inflammation favors their uptake by macrophages and resident cells in the artery wall. The effect of heightened influx of lipids is compounded by impaired HDL-mediated reverse cholesterol transport leading to foam cell formation which is the central event in atherosclerosis plaque formation and subsequent plaque rupture, thrombosis, and tissue damage.

Low-density lipoprotein (LDL) cholesterol is cross-sectionally associated with preclinical chronic kidney disease (CKD) in Japanese men

BACKGROUND

Low-density lipoprotein (LDL) cholesterol and chronic kidney disease (CKD) are both well-known risk factors for cardiovascular disease. However, few studies have examined the associations between LDL cholesterol and CKD.

METHODS

In the present study, we investigated the associations between LDL cholesterol and CKD using medical check-up data from 2,449 Japanese men and 1,448 Japanese women. Metabolic syndrome (MetS) was defined according to the revised National Cholesterol Education Program (NCEP) criteria for Japanese people. CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) and/or proteinuria.

RESULTS

Blood levels of LDL cholesterol were higher in CKD subjects than in non-CKD subjects only in men and the frequency of antihyperlipidemic medication and MetS was higher in CKD subjects than in non-CKD subjects, regardless of gender. The frequency of CKD was significantly higher in male subjects with the highest quartile of LDL cholesterol than in those with the lowest quartile of LDL cholesterol. LDL cholesterol levels were significantly higher in subjects with eGFR corresponding to CKD stages 2 and 3 than in those with eGFR corresponding to CKD stage 1 both in men and women. LDL cholesterol was independently associated with CKD, eGFR <60 mL/min/1.73 m(2), and proteinuria in Japanese men, but not in women.

CONCLUSION

LDL cholesterol is cross-sectionally associated with preclinical CKD in Japanese men.

Lipid abnormalities, lipoprotein (a) and apoprotein pattern in non-dialyzed patients with chronic kidney disease

The present study was carried out to explore the altered lipid, lipoprotein and apoprotein abnormalities along with lipoprotein (a) in chronic kidney disease patients with stage I to V which were further divided into group 1 (stage I and II), group 2 (stage III and IV) and group 3 (stage V). 50 chronic kidney disease patients with stage I to V and 20 healthy normal subjects as controls were recruited for this study. Among the various parameters tested triglyceride levels were high in group 1 and 2, whereas VLDL cholesterol, Lp (a) and apo B levels were significantly high in all the groups when compared to controls (P<0.05). However, LDL cholesterol level was significantly low in group 3 only as compared to control group (P<0.05). Apoprotein AI values also showed significant decrease in all groups as compared to controls (P<0.05). Though total cholesterol levels in group 1 and LDL levels in group 1 and 2 were higher than controls, but the values attained not statistically significant (P>0.05). In conclusion high levels of VLDL cholesterol, Lp (a), apo B and low levels of apoprotein AI as reported in this study are the major lipid disorders in the development of cardiovascular complications at all the stages in these patients.

Niacin improves renal lipid metabolism and slows progression in chronic kidney disease

BACKGROUND

Mounting evidence points to lipid accumulation in the diseased kidney and its contribution to progression of nephropathy. We recently found heavy lipid accumulation and marked dysregulation of lipid metabolism in the remnant kidneys of rats with chronic renal failure (CRF). Present study sought to determine efficacy of niacin supplementation on renal tissue lipid metabolism in CRF.

METHODS

Kidney function, lipid content, and expression of molecules involved in cholesterol and fatty acid metabolism were determined in untreated CRF (5/6 nephrectomized), niacin-treated CRF (50 mg/kg/day in drinking water for 12 weeks) and control rats.

RESULTS

CRF resulted in hypertension, proteinuria, renal tissue lipid accumulation, up-regulation of scavenger receptor A1 (SR-A1), acyl-CoA cholesterol acyltransferase-1 (ACAT1), carbohydrate-responsive element binding protein (ChREBP), fatty acid synthase (FAS), acyl-CoA carboxylase (ACC), liver X receptor (LXR), ATP binding cassette (ABC) A-1, ABCG-1, and SR-B1 and down-regulation of sterol responsive element binding protein-1 (SREBP-1), SREBP-2, HMG-CoA reductase, PPAR-alpha, fatty acid binding protein (L-FABP), and CPT1A. Niacin therapy attenuated hypertension, proteinuria, and tubulo-interstitial injury, reduced renal tissue lipids, CD36, ChREBP, LXR, ABCA-1, ABCG-1, and SR-B1 abundance and raised PPAR-alpha and L-FABP.

CONCLUSIONS AND GENERAL SIGNIFICANCE

Niacin administration improves renal tissue lipid metabolism and renal function and structure in experimental CRF.

Interruption of antiretroviral therapy is associated with increased plasma cystatin C

BACKGROUND

Cystatin C has been proposed as an alternative marker of renal function. We sought to determine whether participants randomized to episodic use of antiretroviral therapy guided by CD4 cell count (drug conservation) had altered cystatin C levels compared with those randomized to continuous antiretroviral therapy (viral suppression) in the Strategies for Management of Antiretroviral Therapy trial, and to identify factors associated with increased cystatin C.

METHODS

Cystatin C was measured in plasma collected at randomization, 1, 2, 4, 8 and 12 months after randomization in a random sample of 249 and 250 participants in the drug conservation and viral suppression groups, respectively. Logistic regression was used to model the odds of at least 0.15 mg/dl increase in cystatin C (1 SD) in the first month after randomization, adjusting for demographic and clinical characteristics.

RESULTS

At randomization, mean (SD) cystatin C level was 0.99 (0.26 mg/dl) and 1.01 (0.28 mg/dl) in the drug conservation and viral suppression arms, respectively (P = 0.29). In the first month after randomization, 21.8 and 10.6% had at least 0.15 mg/dl increase in cystatin C in the drug conservation and viral suppression arms, respectively (P = 0.0008). The difference in cystatin C between the treatment arms was maintained through 1 year after randomization. After adjustment, participants in the viral suppression arm had significantly reduced odds of at least 0.15 mg/dl increase in cystatin C in the first month (odds ratio 0.42; 95% confidence interval 0.23-0.74, P = 0.0023).

CONCLUSION

These results demonstrate that interruption of antiretroviral therapy is associated with an increase in cystatin C, which may reflect worsened renal function.

Managing dyslipidemia in chronic kidney disease

The incidence of chronic kidney disease (CKD) in the U.S. continues to increase, and now over 10% of the U.S. population has some form of CKD. Although some patients with CKD will ultimately develop renal failure, most patients with CKD will die of cardiovascular disease before dialysis becomes necessary. Patients with CKD have major proatherogenic lipid abnormalities that are treatable with readily available therapies. The severe derangements seen in lipoprotein metabolism in patients with CKD typically results in high triglycerides and low high-density lipoprotein (HDL) cholesterol. Because of the prevalence of triglyceride disorders in patients with CKD, after treating patients to a low-density lipoprotein goal, non-HDL should be calculated and used as the secondary goal of treatment. A review of the evidence from subgroup analysis of several landmark lipid-lowering trials supports treating dyslipidemia in mild to moderate CKD patients with HMG-CoA reductase inhibitors. The evidence to support treating dyslipidemia in hemodialysis patients, however, has been mixed, with several outcome trials pending. Patients with CKD frequently have mixed dyslipidemia and often require treatment with multiple lipid-lowering drugs. Although statins are the cornerstone of therapy for most patients with CKD, differences in their pharmacokinetic properties give some statins a safety advantage in patients with advanced CKD. Although most other lipid-lowering agents can be used safely with statins in combination therapy in patients with CKD, the fibrates are renally metabolized and require both adjustments in dose and very careful monitoring due to the increased risk of rhabdomyolysis. After reviewing the safety and dose alterations required in managing dyslipidemia in patients with CKD, a practical treatment algorithm is proposed.