High-calorie supplementation increases serum leptin levels and improves response to rHuEPO in long-term hemodialysis patients

Understanding the complexity of barriers and facilitators to adherence to oral nutritional supplements among patients with malnutrition: a systematic mixed-studies review

The aim of this systematic mixed-studies review is to summarise barriers/facilitators to adherence to and/or consumption of oral nutritional supplements (ONS) among patients with disease-related malnutrition. In March 2022, the Cochrane CENTRAL, PUBMED, PsycINFO (Ovid) and CINAHL were searched for articles with various study designs, published since 2000. Articles were identified on the basis of 'population' (patients ≥18 years with malnutrition/at nutritional risk), 'intervention' (ONS with ≥2 macronutrients and micronutrients), 'comparison' (any comparator/no comparator) and 'outcome' (factors affecting adherence or consumption) criteria. A sequential exploratory synthesis was conducted: first, a thematic synthesis was performed identifying barriers/facilitators; and second, the randomised controlled trials (RCTs) were used to support these findings. The five WHO dimensions of adherence guided the analysis. Study inclusion, data extraction, analysis and risk-of-bias assessment (MMAT 2018) were carried out independently by two researchers. From 21 835 screened articles, 171 were included with 42% RCTs and 20% qualitative studies. The two major populations were patients with malignancies (34%) and older adults (35%). In total, fifty-nine barriers/facilitators were identified. Patients' health status, motivation, product tolerance and satisfaction as well as well-functioning healthcare routines and support were factors impacting ONS consumption. Few barriers/facilitators (n = 13) were investigated in RCTs. Two of those were serving a small ONS volume and integrating ONS into ward routines. Given the complexity of ONS adherence, non-adherence to ONS should be addressed using a holistic approach. More studies are needed to investigate the effect of different approaches to increase adherence to ONS.

Erythropoiesis-stimulating agents for anaemia in adults with chronic kidney disease: a network meta-analysis

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anaemia in people with chronic kidney disease (CKD). However, their use has been associated with cardiovascular events. This is an update of a Cochrane review first published in 2014.

OBJECTIVES

To compare the efficacy and safety of ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, and biosimilar ESAs against each other, placebo, or no treatment) to treat anaemia in adults with CKD.

SEARCH METHODS

In this update, we searched the Cochrane Kidney and Transplant Register of Studies up to 29 April 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that included a comparison of an ESA (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, a biosimilar epoetin or a biosimilar darbepoetin alfa) with another ESA, placebo or no treatment in adults with CKD were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two independent authors screened the search results and extracted data. Data synthesis was performed using random-effects pairwise meta-analysis (expressed as odds ratios (OR) and their 95% confidence intervals (CI)) and network meta-analysis. We assessed for heterogeneity and inconsistency within meta-analyses using standard techniques and planned subgroup and meta-regression to explore sources of heterogeneity or inconsistency. We assessed certainty in treatment estimates for the primary outcomes (preventing blood transfusions and death (any cause)) using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Sixty-two new studies (9237 participants) were included in this update, so the review now includes 117 studies with 25,237 participants. Most studies were at high or unclear risk of bias in most methodological domains. Overall, results remain similar in this update compared to our previous review in 2014. For preventing blood transfusion, epoetin alfa (OR 0.28, 95% CI 0.13 to 0.61; low certainty evidence) and epoetin beta (OR 0.19, 95% CI 0.08 to 0.47; low certainty evidence) may be superior to placebo, and darbepoetin alfa was probably superior to placebo (OR 0.27, 95% CI 0.11 to 0.67; moderate certainty evidence). Methoxy polyethylene glycol-epoetin beta (OR 0.33, 95% CI 0.11 to 1.02; very low certainty evidence), a biosimilar epoetin (OR 0.34, 95% CI 0.11 to 1.03; very low certainty evidence) and a biosimilar darbepoetin alfa (OR 0.37, 95% CI 0.07 to 1.91; very low certainty evidence) had uncertain effects on preventing blood transfusion compared to placebo. The comparative effects of ESAs compared with another ESA on preventing blood transfusions were uncertain, in low to very low certainty evidence. Effects on death (any cause) were uncertain for epoetin alfa (OR 0.79, 95% CI 0.51 to 1.22; low certainty evidence), epoetin beta (OR 0.69, 95% CI 0.40 to 1.20; low certainty evidence), methoxy polyethylene glycol-epoetin beta (OR 1.07, 95% CI 0.67 to 1.71; very low certainty evidence), a biosimilar epoetin (OR 0.80, 95% CI 0.47 to 1.36; low certainty evidence) and a biosimilar darbepoetin alfa (OR 1.63, 95% CI 0.51 to 5.23; very low certainty evidence) compared to placebo. There was probably no difference between darbepoetin alfa and placebo on the odds of death (any cause) (OR 0.99, 95% CI 0.81 to 1.21; moderate certainty evidence). The comparative effects of ESAs compared with another ESA on death (any cause) were uncertain in low to very low certainty evidence. Epoetin beta probably increased the odds of hypertension when compared to placebo (OR 2.17, 95% CI 1.17 to 4.00; moderate certainty evidence). Compared to placebo, epoetin alfa (OR 2.10, 95% CI 1.22 to 3.59; very low certainty evidence), darbepoetin alfa (OR 1.88, 95% CI 1.12 to 3.14; low certainty evidence) and methoxy polyethylene glycol-epoetin beta (OR 1.98, 95% CI 1.05 to 3.74; low certainty evidence) may increase the odds of hypertension, but a biosimilar epoetin (OR 1.88, 95% CI 0.96 to 3.67; low certainty evidence) and biosimilar darbepoetin alfa (OR 1.98, 95% CI 0.84 to 4.66; low certainty evidence) had uncertain effects on hypertension. The comparative effects of all ESAs compared with another ESA, placebo or no treatment on cardiovascular death, myocardial infarction, stroke, vascular access thrombosis, kidney failure, and breathlessness were uncertain. Network analysis for fatigue was not possible due to sparse data.  AUTHORS' CONCLUSIONS: The comparative effects of different ESAs on blood transfusions, death (any cause and cardiovascular), major cardiovascular events, myocardial infarction, stroke, vascular access thrombosis, kidney failure, fatigue and breathlessness were uncertain.

Responsiveness to an erythropoiesis-stimulating agent is correlated with body composition in patients undergoing chronic hemodialysis

BACKGROUND

Resistance to erythropoiesis-stimulating agents (ESA) is associated with adverse outcomes in patients undergoing chronic hemodialysis. However, the impact of body composition on ESA response remains uncertain. This study retrospectively investigated whether there is an association between the ESA resistance index (ERI) and body composition in patients undergoing chronic hemodialysis.

METHODS

Multifrequency bioelectrical impedance analysis was used to measure body composition every six months. The ERI was calculated by dividing the weekly body weight-adjusted erythropoietin dose by the hemoglobin concentration. The ERI values were recorded every three months.

RESULTS

A total of 123 patients were followed up for 24 (interquartile range 5, 75) months. The ERI was negatively correlated with body mass index, arm circumference, arm muscle circumference, body fat percentage, and visceral fat area (P = 0.057, 0.001, 0.017, 0.063, and 0.041, respectively). Patients with a higher mean ERI during the study period had an increased risk of all-cause mortality, cardiovascular events, and infection requiring hospitalization than those with a lower mean ERI (P = 0.027, 0.021, and 0.037, respectively). We also evaluated the association between the slope of body composition parameters and the ERI trend over time and found that the ERI increased over time in patients who had an increased ratio of extracellular water to total body water (P = 0.002) as well as decreased arm circumference, arm muscle circumference, visceral fat area, and phase angle (P = 0.001, P < 0.001, P = 0.036, and 0.002).

CONCLUSION

ESA responsiveness appears to be associated with body composition in patients undergoing chronic hemodialysis. Therefore, measures improving body composition, such as nutrition and exercise, may have a favorable effect on the response to ESA.

New Insights into Adiponectin and Leptin Roles in Chronic Kidney Disease

Chronic kidney disease (CKD) is commonly associated with a high burden of comorbidities and poor clinical outcomes. Malnutrition–inflammation–atherosclerosis syndrome is common in the more severe stages of CKD, suggesting a close interplay for these three comorbid conditions. Both malnutrition and obesity are associated with a disturbed adipokine profile and inflammation, contributing to a higher risk of cardiovascular disease (CVD) events. Adiponectin and leptin have important roles in carbohydrate and lipid metabolism, and in the inflammatory process. The effects of adiponectin and leptin alterations in CKD, which are usually increased, and their association with the different comorbidities found in CKD, will be focused on to understand their crosstalk with the risk of CVD events. Nonetheless, although adiponectin and leptin contribute to a higher risk of CVD events, further studies are warranted to fully clarify their roles, especially when different comorbidities exist.

Sleep Quality After Intradialytic Oral Nutrition: A New Benefit of This Anabolic Strategy? A Pilot Study

Background

Since disturbances of appetite and sleep are closely related and both affect metabolic disorders, it would be expected that a renal specific oral nutritional supplement (RS-ONS) that covers the energy the patient does not consume on the HD day, could contribute to improve the nutritional status and body composition, as well as sleep quality. There is still scarce information related to this topic.

Aim

To evaluate the effect of the use of intra-dialytic RS-ONS vs. RS-ONS at home on sleep quality, nutritional status, and body composition in patients on HD.

Methods

Adult patients &lt; 65 years, with ≥3 months on HD were invited to participate in an open randomized pilot study (ISRCTN 33897). Patients were randomized to a dialysis-specific high-protein supplement provided during the HD session (Intradialytic oral nutrition [ION]) or at home (control), during non-HD days (thrice weekly, for both) 12 weeks. The primary outcome was sleep quality defined by the Pittsburgh Sleep Quality Index (PSQI) score. Nutritional assessment included Malnutrition Inflammation Score (MIS), bioelectrical impedance analysis, anthropometry, 3-day food records, and routine blood chemistries.

Results

A total of 23 patients completed the study. Age was median 35 (range 24–48 years), 42% were women. At baseline, the PSQI score was median 4 (range 2–7), and MIS showed a median of 6 (range 5–8); there were no baseline differences between groups. After intervention, both groups improved their MIS scores and similarly when we analyzed the whole cohort (pre- vs. post-intervention P &lt; 0.01). Patients in the ION group improved the overall PSQI score to median 3 (2–5), and assessment of sleep duration and sleep disturbances (pre- vs. post-intervention P &lt; 0.05), with a trend toward an effect difference compared to patients consuming the supplement at home (P for treatment-effect across arms 0.07 for PSQI score and 0.05 for sleep latency).

Conclusion

Oral supplementation improved nutritional status in the whole cohort, but only ION improved the PSQI score. More studies are needed to explore the nutritional strategies that influence the relationship between sleep and nutritional status in HD patients.

[Prevalence of malnutrition and absolute and functional iron deficiency anemia in nondialysis-dependent chronic kidney disease and hemodialysis Algerian patients]

In chronic kidney disease, anemia and malnutrition coupled with inflammation as malnutrition-inflammation complex syndrom are common and considered as morbidity-mortality factors. The link between these two factors has been described at length in the literature highlighting an association of malnutrition with iron deficiency considered itself as one of the causes of anemia in chronic kidney disease (non-dialysis and hemodialysis). Our study aims to know the prevalence of these two factors in a population of chronic kidney disease (non-dialysis and hemodialysis) of Algiers and to highlight the possible associations between them.

PATIENTS AND METHODS

This is a multicentre, cross-sectional and descriptive study carried out over a period of 6months (August 2018 to January 2019). Anemia and malnutrition were assessed by various biological and clinical tools such as the malnutrition inflammation score and the International Society of Renal Nutrition and Metabolism criteria. Statistical tests were performed on the R studio software, considering P<0.05 as a statistically significant value.

RESULTS

Two hundred and nine patients on chronic kidney disease were included (90 non dialysis and 119 hemodialysis). The median age was 70 (IQR=16) for non dialysis and 56 (IQR=16.5) for hemodialysis. The prevalence of anemia was 66.66% (n=60) in non dialysis and 70.58% (n=84) in hemodialysis. Absolute iron deficiency anemia was higher in non dialysis (48.33%; n=29) while functional iron deficiency anemia was higher in hemodialysis (34.52%; n=29). The prevalence of malnutrition by malnutrition inflammation score was relatively low. Only functional iron deficiency anemia was associated with malnutrition.

CONCLUSION

The prevalence of anemia was higher in Algerian chronic kidney disease (non-dialysis and hemodialysis) unlike malnutrition which remains associated with functional iron deficiency anemia.

How Is Body Composition and Nutrition Status Associated with Erythropoietin Response in Hemodialyzed Patients? A Single-Center Prospective Cohort Study

Background: Anemia is the most common finding in patients with end-stage kidney disease undergoing renal replacement therapy. A certain percentage of patients does not respond adequately to erythropoietin (EPO) treatment, not being able to reach desirable hemoglobin levels even when treated with large-dose EPO and intravenous/oral iron. In our study, we wanted to further investigate how nutritional status is associated with erythropoietin responsiveness. To quantify EPO response, we used the Erythropoietin Resistance Index (ERI), which is defined as the weekly weight-adjusted dose of EPO divided by the hemoglobin level. Patients and methods: Seventy-eight patients undergoing hemodialysis were included. All of them were measured by a SECA mBCA body composition analyzer and evaluated by Kalantar-Zadeh’s MIS score. Routine biochemical tests were also taken into account. The Shapiro-Wilk test was used to study the distributions of quantitative variables, which were significantly different from normal (p < 0.05). We used nonparametric Mann-Whitney U-test to compare groups. Correlations were studied by means of Spearman’s rank correlation coefficient. Bonferroni correction for multiple testing was performed. To find independent determinants of ERI, we additionally performed multivariate analysis using the General Linear Model (GLM). Results: In terms of body composition, factors that are associated with high ERI are low BMI, low fat mass, low visceral fat volume, high total body water percentage, low phase angle and low fat-free mass. In addition to body composition parameters, total MIS score and IL-6 serum levels correlated positively with ERI value. IL-6 was an independent determinant of ERI value, based on multivariate analysis. After correction for multiple analysis, BMI and eGFR both remained significant factors associated with EPO response. Conclusions: It seems crucial to prevent inflammatory malnutrition as a part of a holistic approach to anemia treatment in dialysis patients.

Nutritional status improvement in elderly CKD patients: a systematic review

PURPOSE

Almost all CKD patients have a poor nutritional status, while elderly CKD patients are specifically frail and malnourished. Our aim is to conduct a systematic review of the up to date primary studies that look at methods of improving nutritional status in CKD patients in the elderly demographic.

METHODS

A focussed and sensitive search strategy was applied to the PUBMED database to identify relevant English language articles. Once articles were identified a detailed quality and bias assessment was performed. Two independent researchers (MZ and SM) then subsequently carried out detailed data extraction and analysis and this was subsequently verified by a third researcher (IN).

RESULTS

A total of 19 studies were included in our systematic review which included 7 non-randomised control trials and 15 randomised controlled trials. The outcomes that we considered to be most relevant for our subject title were: mortality data, SGA, albumin, total protein, isoleucine, leucine, prealbumin, transferrin, leptin, valine, TAG, HDL, LDL and total amino acids. Detailed bias analysis of the different studies was also conducted.

CONCLUSION

This is the first systematic review of the literature, so far, on the subject, involving elderly CKD patients. The quality of trials is low, very heterogenic in patients, methods and outcomes. However, we found a positive effect of dietary interventions on the nutritional status of most patients studied, highlighted by improvement in serum albumin and SGA, the most measured outcomes.

Pathogenesis and Treatment Options of Cancer Related Anemia: Perspective for a Targeted Mechanism-Based Approach

Cancer-related anemia (CRA) is a common sign occurring in more than 30% of cancer patients at diagnosis before the initiation of antineoplastic therapy. CRA has a relevant influence on survival, disease progression, treatment efficacy, and the patients' quality of life. It is more often detected in patients with advanced stage disease, where it represents a specific symptom of the neoplastic disease, as a consequence of chronic inflammation. In fact, CRA is characterized by biological and hematologic features that resemble those described in anemia associated to chronic inflammatory disease. Proinflammatory cytokine, mainly IL-6, which are released by both tumor and immune cells, play a pivotal action in CRA etiopathogenesis: they promote alterations in erythroid progenitor proliferation, erythropoietin (EPO) production, survival of circulating erythrocytes, iron balance, redox status, and energy metabolism, all of which can lead to anemia. The discovery of hepcidin allowed a greater knowledge of the relationships between immune cells, iron metabolism, and anemia in chronic inflammatory diseases. Additionally, chronic inflammation influences a compromised nutritional status, which in turn might induce or contribute to CRA. In the present review we examine the multifactorial pathogenesis of CRA discussing the main and novel mechanisms by which immune, nutritional, and metabolic components affect its onset and severity. Moreover, we analyze the status of the art and the perspective for the treatment of CRA. Notably, despite the high incidence and clinical relevance of CRA, controlled clinical studies testing the most appropriate treatment for CRA are scarce, and its management in clinical practice remains challenging. The present review may be useful to indicate the development of an effective approach based on a detailed assessment of all factors potentially involved in the pathogenesis of CRA. This mechanism-based approach is essential for clinicians to plan a safe, targeted, and successful therapy, thereby promoting a relevant amelioration of patients' quality of life.

Serum leptin level is associated with phase angle in CKD5 patients not undergoing dialysis

Objective

Malnutrition is very complex in patients with end-stage renal disease (ESRD) and is associated with poor prognosis. This is because hemodynamic changes, hormonal changes, persistent inflammatory reactions, and fluid overloads are more complicated as uremia is worsening. Bio-impedance spectroscopy (BIS) is a useful method to estimate fluid balance (Overhydration/ extracellular water, OH/ECW) and nutritional status (Phase angle, PhA). We aimed to evaluate the volume and nutritional status by BIS and to investigate the relationship between the appetite regulating hormones and the parameters of BIS in patients with stage 5 chronic kidney disease not undergoing dialysis (CKD5-ND).

Methods

We enrolled a total of 91 CKD5-ND patients. We measured routine serum markers including albumin and NT-proBNP and the appetite regulating hormones, leptin and ghrelin. We defined poor nutritional status as a PhA < 4.5°, and proper nutritional status as a PhA ≥ 4.5°. We also evaluated each patient’s nutritional status by assessing their geriatric nutritional risk index (GNRI) and their volume status by measuring NT-proBNP.

Results

Forty-one patients (45%) had poor nutritional status. Patients with a poor nutritional status had significantly higher OH/ECW (29.6 ± 12.7% vs. 6.2 ± 10.3%, p<0.001) and lower levels of leptin (3.8 ± 3.1 vs. 7.0 ± 6.2 ng/mL, p = 0.004) than those with proper nutritional status. PhA was associated with GNRI (r = 0.597, P<0.001) and NT-proBNP was associated with OH/ECW (r = 0.384, P<0.001). Leptin was negatively correlated with OH/ECW (r = -0.288, p = 0.006). In contrast, leptin was positively correlated with PhA (r = 0.263, p = 0.012). In multivariate logistic regression, high level of leptin (OR 7.00, 95% CI 1.74–28.10) was associated with proper nutrition, while an increased OH/ECW (OR 0.65, 95% CI 0.51–0.84) was associated with poor nutrition.

Conclusions

Our study demonstrates that CKD5-ND patients with poor nutrition generally also suffer from excessive body fluid. Low leptin level suggests poor nutrition in CKD5-ND patients. PhA could be used as a nutritional index for ESRD patients.

Association of Increased Serum Leptin with Ameliorated Anemia and Malnutrition in Stage 5 Chronic Kidney Disease Patients after Parathyroidectomy

Leptin is an adipokine that regulates various metabolism, but its association with secondary hyperparathyroidism (SHPT), a clinical manifestation of chronic kidney disease-mineral and bone disorder (CKD-MBD), remains obscure. Parathyroidectomy (PTX) is recommended for severe SHPT patients. Here, the associations between circulating leptin and clinical characteristics in CKD patients were investigated. Effects of PTX on leptin production were analyzed in vivo and in vitro. Controls and CKD patients had approximate serum leptin levels in that a larger proportion of CKD patients with body mass index (BMI) <23 kg/m². Serum leptin was related to anemia, albumin, and bone metabolism disorders in CKD patients. Lower intact parathyroid hormone (PTH) was related with higher leptin in PTX patients group. Severe SHPT inhibited uremia-enhanced leptin production in 3T3-L1 adipocytes, which was attenuated after PTX. High levels of PTH were found to reduce Akt phosphorylation and leptin production in vitro but high levels of calcium and phosphorus were not. Successful PTX was found to improve anemia and malnutrition in severe SHPT patients, and this was correlated with increased circulating leptin levels via up-regulated Akt signaling in adipocytes. These findings indicated the therapeutic potential of leptin and related target pathway for improving survival and quality of life in CKD.

Adipokines promote chronic kidney disease

The rapid growth in obesity worldwide contributes to an increase in metabolic syndrome and obesity-related kidney disease with an enhanced increased risk for chronic kidney disease, finally progressing to end-stage renal disease. Adipose tissue is a highly active endocrine organ secreting numerous factors that contribute to renal and cardiovascular complications. In renal damage, various adipokines are involved through mediating endothelial dysfunction, inducing oxidative stress and inflammation as well as stimulating renal sympathetic nervous activity, and it reduces cancellous bone but conversely increases cortical bone. Adipokines may also be involved in the development of renal anaemia. A balance exists between more protective adipokines (adiponectin) and factors mediating pathophysiological effects (angiotensin II, TNFα). Obesity may cause a disruption of this delicate balance, thereby inducing renal disease. Consequently, weight reduction and lifestyle changes affecting all components of the metabolic syndrome are essential to disrupt this vicious cycle.

The association of leptin and homocysteine with renal function impairment in a population of Taiwanese adults

BACKGROUND & AIMS

Higher levels of leptin and homocysteine (Hcy) have been evaluated as risk factors of chronic kidney disease in patients and general population. The aim of this study was to examine gender differences in the associations of leptin and Hcy levels and renal function a representative healthy young population in Taiwan.

METHODS

The participants aged ≥18 years who underwent health examinations were included and categorized into three groups by gender-specific tertiles of leptin and Hcy levels. Estimated glomerular filtration rates (eGFR) were estimated according to the modified equation of Modification of Diet in Renal Disease (MDRD).

RESULTS

A higher mean Hcy level was found in male subjects than females. Mean values of metabolic syndrome risk factors significantly elevated with increasing leptin levels in both genders. Both male and female subjects with higher plasma Hcy levels were more likely to have a lower eGFR. Plasma Hcy levels were significantly negatively correlated with eGFR in linear regression models adjusted for age and smoking. The associations persisted even after mean arterial pressure and fasting plasma glucose were included for adjustments both genders. Plasma Hcy level was negatively associated eGFR and the association was more profound for females.

CONCLUSIONS

Leptin levels did not reveal strong or consistent evidence to support a significant association with eGFR. Hcy had a more decisive effect on renal function impairment than leptin and may be considered a more sensitive biomarker for Taiwanese adults.

The role of inflammation, iron, and nutritional status in cancer-related anemia: results of a large, prospective, observational study

Anemia in oncology patients is often considered a side effect of cancer therapy; however, it may occur before any antineoplastic treatment (cancer-related anemia). This study was aimed to evaluate the prevalence of cancer-related anemia in a large cohort of oncology patients and whether inflammation and malnutrition were predictive of its development and severity. The present study included 888 patients with cancer at different sites between May 2011 and January 2014. Patients were assessed at diagnosis before any cancer treatment. The prevalence of anemia according to the main clinical factors (tumor site, stage and performance status) was analyzed. In each patient markers of inflammation, iron metabolism, malnutrition and oxidative stress as well as the modified Glasgow prognostic score, a combined index of malnutrition and inflammation, were assessed and their role in predicting hemoglobin level was evaluated. The percentage of anemic patients was 63% with the lowest hemoglobin levels being found in the patients with most advanced cancer and compromised performance status. Hemoglobin concentration differed by tumor site and was lowest in patients with ovarian cancer. Hemoglobin concentration was inversely correlated with inflammatory markers, hepcidin, ferritin, erythropoietin and reactive oxygen species, and positively correlated with leptin, albumin, cholesterol and antioxidant enzymes. In multivariate analysis, stage, interleukin-6 and leptin were independent predictors of hemoglobin concentration. Furthermore, hemoglobin was inversely dependent on modified Glasgow Prognostic Score. In conclusion, cancer-related anemia is a multifactorial problem with immune, nutritional and metabolic components that affect its severity. Only a detailed assessment of the pathogenesis of cancer-related anemia may enable clinicians to provide safe and effective individualized treatment.

Ten days of simulated live high:train low altitude training increases Hbmass in elite water polo players

Objectives

Water polo requires high aerobic power to meet the demands of match play. Live high:train low (LHTL) may enhance aerobic capacity at sea level. Before the Olympics, the Australian women's water polo team utilised LHTL in an attempt to enhance aerobic fitness.

Methods

Over 6 months, 11 players completed three normobaric LHTL exposures (block 1:11 days at 3000 m; block 2+3:9 days at 2500 m, 11 days normoxia, 10 days at 2800 m). Haemoglobin mass (Hbmass) was measured through carbon monoxide-rebreathing. Before each block, the relationship between Hbmass and water polo-specific aerobic fitness was investigated using the Multistage Shuttle Swim Test (MSST). Effect size statistics were adopted with likely, highly likely and almost certainly results being >75%, >95%, >99%, respectively. A Pearson product moment correlation was used to characterise the association between pooled data of Hbmass and MSST.

Results

Hbmass (mean±SD, pre 721±66 g) likely increased after block 1 and almost certainly after block 2+3 (% change; 90% confidence limits: block 1: 3.7%; 1.3–6.2%, block 2+3: 4.5%; 3.8–5.1%) and the net effect was almost certainly higher after block 2+3 than before block 1 (pre) by 8.5%; 7.3–9.7%. There was a very large correlation between Hbmass (g/kg) and MSST score (r=0.73).

Conclusions

LHTL exposures of <2 weeks induced approximately 4% increase in Hbmass of water polo players. Extra Hbmass may increase aerobic power, but since match performance is nuanced by many factors it is impossible to ascertain whether the increased Hbmass contributed to Australia's Bronze medal.

Interventions for erythropoietin-resistant anaemia in dialysis patients

BACKGROUND

People living with end-stage kidney disease (ESKD) often develop anaemia. Erythropoiesis-simulating agents (ESAs) are often given to people living with ESKD to maintain haemoglobin at a level to minimise need for transfusion. However, about 5% to 10% of patients with ESKD exhibit resistance to ESAs, and observational studies have shown that patients requiring high doses of ESA are at increased risk of mortality.

OBJECTIVES

This review aimed to study the effects of interventions for the treatment of ESA-resistant anaemia in people with ESKD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE for randomised controlled trials (RCT) that involved participants with ESKD on dialysis or who were pre-dialysis patients with chronic kidney disease (stage 5). Date of last search: April 2013.

SELECTION CRITERIA

ESA resistance was defined as failure to achieve or maintain haemoglobin/haematocrit levels within the desired target range despite appropriate ESA doses (erythropoietin ≥ 450 U/kg/wk intravenously or ≥ 300 U/kg/wk subcutaneously; darbepoetin ≥ 1.5 µg/kg/wk) in people who were not nutritionally deficient, or who had haematological or bleeding disorders. Extended inclusion criteria for ESA hyporesponsive state were: erythropoietin dose ≥ 300 U/kg/wk and ≥ 150 U/kg/wk for intravenous administration; or ≥ 200 U/kg/wk and ≥ 100 U/kg/wk for subcutaneous administration; or darbepoetin dose ≥ 1.0 µg/kg/wk).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using a random effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Titles and abstracts of 521 records were screened, of which we reviewed 99 from the full text. Only two studies matched our inclusion criteria. One study compared intravenous vitamin C versus no study medication for six months in 42 ESKD patients on haemodialysis who required intravenous erythropoietin (dose ≥ 450 U/kg/wk). The other included study compared high-flux dialyser versus low-flux dialyser for six months in 48 haemodialysis patients who required subcutaneous erythropoietin (dose ≥ 200 U/kg/wk). Because interventions differed, data could not be combined for quantitative meta-analysis.

AUTHORS' CONCLUSIONS

There was inadequate evidence identified to inform recommendation of any intervention to ameliorate ESA hyporesponsiveness. Adequately powered RCTs are required to establish the safety and efficacy of interventions to improve responsiveness to ESA therapy.

The role of novel biomarkers of cardiovascular disease in chronic kidney disease: focus on adiponectin and leptin

Cardiovascular disease (CVD) remains a major cause of premature death in patients with chronic kidney disease (CKD), including renal transplant recipients. Both interplay of traditional cardiovascular and renal specific risk factors have been shown to be associated with an increased risk of cardiovascular death in patients with CKD. Recently, there has been great interest in the role of novel biomarkers, in particular adiponectin and leptin, and its association with CVD in the CKD population. Adiponectin is a multifunctional adipocyte-derived protein with anti-inflammatory, antiatherogenic and insulin sensitizing activity. Recent observational studies have shown adiponectin to be a novel risk marker of CVD in patients with stages 1 to 5 CKD. Leptin is an adipocyte-derived hormone that promotes weight loss by decreasing food intake. Similarly, there are observational studies to support an association between leptin and CVD, including patients with CKD. In the CKD population, leptin may be associated with uremic cachexia and subsequent increased mortality. This review aims to summarize the pathophysiological and potential clinical roles of these cardiovascular biomarkers in patients with CKD.

Longitudinal study of leptin levels in chronic hemodialysis patients

Background

The influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated. We conducted a prospective longitudinal study of leptin levels and nutritional parameters to determine whether changes of serum leptin levels modify nutritional status and survival in a cohort of prevalent hemodialysis patients.

Methods

Leptin, dietary energy and protein intake, biochemical markers of nutrition and body composition (anthropometry and bioimpedance analysis) were measured at baseline and at 6, 12, 18 and 24 months following enrollment, in 101 prevalent hemodialysis patients (37% women) with a mean age of 64.6 ± 11.5 years. Observation of this cohort was continued over 2 additional years. Changes in repeated measures were evaluated, with adjustment for baseline differences in demographic and clinical parameters.

Results

Significant reduction of leptin levels with time were observed (linear estimate: -2.5010 ± 0.57 ng/ml/2y; p < 0.001) with a more rapid decline in leptin levels in the highest leptin tertile in both unadjusted (p = 0.007) and fully adjusted (p = 0.047) models. A significant reduction in body composition parameters over time was observed, but was not influenced by leptin (leptin-by-time interactions were not significant). No significant associations were noted between leptin levels and changes in dietary protein or energy intake, or laboratory nutritional markers. Finally, cumulative incidences of survival were unaffected by the baseline serum leptin levels.

Conclusions

Thus leptin levels reflect fat mass depots, rather than independently contributing to uremic anorexia or modifying nutritional status and/or survival in chronic hemodialysis patients. The importance of such information is high if leptin is contemplated as a potential therapeutic target in hemodialysis patients.

Obesity hypertension: the regulatory role of leptin

Leptin is a 16-kDa-peptide hormone that is primarily synthesized and secreted by adipose tissue. One of the major actions of this hormone is the control of energy balance by binding to receptors in the hypothalamus, leading to reduction in food intake and elevation in temperature and energy expenditure. In addition, increasing evidence suggests that leptin, through both direct and indirect mechanisms, may play an important role in cardiovascular and renal regulation. While the relevance of endogenous leptin needs further clarification, it appears to function as a pressure and volume-regulating factor under conditions of health. However, in abnormal situations characterized by chronic hyperleptinemia such as obesity, it may function pathophysiologically for the development of hypertension and possibly also for direct renal, vascular, and cardiac damage.

High-calorie diet with moderate protein restriction prevents cachexia and ameliorates oxidative stress, inflammation and proteinuria in experimental chronic kidney disease

BACKGROUND

In earlier studies we found that a high-fat, high-energy diet (HFED) attenuates proteinuria, azotemia and lipid accumulation in the remnant kidney of rats subjected to 5/6 nephrectomy. This study was conducted to explore the mechanism of the salutary effect of HFED in association with moderate protein restriction in this model.

METHODS

The 5/6 nephrectomized male rats were randomized to receive regular rat chow (CRF group, n = 6) or HFED diet (CRF + HFED, n = 7) for 12 weeks. Sham-operated rats served as controls (n = 6).

RESULTS

The CRF group exhibited azotemia, hypertension, proteinuria, diminished body weight, oxidative stress, glomerulosclerosis, tubulo-interstitial inflammation and upregulation of pro-oxidant [NAD(P)H oxidase], pro-inflammatory (NF-κB activation, increased MCP-1, lipoxygenase, ICAM-1, VCAM-1), pro-fibrotic (TGF-β, CTGF) and pro-apoptotic pathways (Bax, caspase-3) in the remnant kidney. Consumption of the HFED resulted in a 66% increment in lipid intake, 8% increment in carbohydrate intake and a 24% reduction in protein intake. The CRF + HFED group gained weight normally, had increments in leptin and adiponectin levels, and despite increments in plasma cholesterol and fatty acids, showed significant attenuation of oxidative stress, proteinuria and inflammation, and partial reversal of the remnant kidney upregulation of pro-oxidant, pro-inflammatory, pro-fibrotic and pro-apoptotic pathways.

CONCLUSION

Consumption of high-energy diet in association with mild protein restriction results in suppression of upregulated pathways that drive progression of renal injury in the remnant kidney model. These findings may have relevance in the management of chronic kidney disease in humans.

High-calorie diet partially ameliorates dysregulation of intrarenal lipid metabolism in remnant kidney

Chronic renal failure (CRF) is associated with malnutrition and renal tissue accumulation of lipids, which can contribute to progression of renal disease. This study was designed to explore the effect of a high-calorie diet on pathways involved in lipid metabolism in the remnant kidney of rats with CRF. 5/6 nephrectomized rats were randomized to receive a regular diet (3.0 kcal/g) or a high-calorie diet (4.5 kcal/g) for 12 weeks. Renal lipid contents and abundance of molecules involved in cholesterol and fatty acid metabolism were studied. The CRF group consuming a regular diet exhibited growth retardation; azotemia; proteinuria; glomerulosclerosis; tubulointerstitial injury; heavy lipid accumulation in the remnant kidney; up-regulation of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), ATP-binding cassette transporter-1 (ABCA1), liver X receptor (LXR) α/β, carbohydrate-responsive element binding protein (ChREBP) and acyl-CoA carboxylase (ACC); and down-regulation of peroxisome proliferator-activated receptor-α (PPAR-α), carnitine palmitoyltransferase-1 (CPT1) and liver-type fatty acid binding protein (L-FABP). The high-calorie diet restored growth; reduced the severity of tubulointerstitial injury, proteinuria and azotemia; partially lowered renal tissue lipid contents; attenuated the up-regulation of mediators of lipid influx (LOX-1), lipid efflux (LXR-α/β and ABCA1) and fatty acid biosynthesis (ChREBP and ACC); and reversed the down-regulation of factors involved in fatty acid oxidation (PPAR-α, CPT1 and L-FABP). In conclusion, a high-calorie diet restores growth, improves renal function and structure, and lowers lipid burden in the remnant kidney. The latter is associated with and most likely due to reduction in lipid influx and enhancement of fatty acid oxidation.

Adiposity and insulin resistance in nondiabetic hemodialysis patients: effects of high energy supplementation

BACKGROUND

In contrast to the general population, a higher body mass index is associated with better survival among hemodialysis patients. Theoretically, high energy supplementation in these patients ought to lead to weight gain over time, but the benefits of this strategy are unclear.

OBJECTIVE

The objective was to assess whether high energy supplementation in nondiabetic hemodialysis patients might adversely affect insulin resistance -- a known risk factor for cardiovascular disease.

DESIGN

We first investigated the association between body fat mass and insulin resistance (homeostasis model assessment of insulin resistance; HOMA-IR) in nondiabetic hemodialysis patients in a cross-sectional analysis (study 1). Of the 106 individuals studied, 55 were randomly assigned to either high energy supplementation (an extra 475 kcal/d; n = 28) or not (n = 27) for 12 wk to assess prospective changes in body fat mass and insulin resistance (study 2).

RESULTS

In study 1, body fat mass (P < 0.05) and C-reactive protein (CRP) (P < 0.05) each contributed independently to HOMA-IR. In study 2, 41 patients completed the study. The 20 patients who received high energy supplementation had a significantly greater increase in body fat mass (P < 0.05), CRP (P < 0.05), and HOMA-IR (P < 0.001) than did the 21 controls.

CONCLUSIONS

Body fat mass and CRP are primary determinants of insulin resistance in nondiabetic hemodialysis patients. High energy supplementation, because it increases adiposity and inflammation, exacerbates insulin resistance. A long-term study is needed to clarify the metabolic effects of high energy supplementation on cardiovascular disease outcomes in hemodialysis patients.

Anemia, nutritional status, and inflammation in hospitalized elderly

OBJECTIVE

Anemia (hemoglobin <120 g/L) in elderly patients is a health problem. The aim of this study was to investigate the prevalence of anemia and associations of anemia with nutritional status and inflammation in hospitalized elderly.

METHODS

Sixty patients from the Department of Geriatrics were randomly assigned to participate. Blood samples were drawn and analyzed at the laboratory of the University Hospital in Reykjavik. Nutritional status was assessed using anthropometric and hematologic parameters.

RESULTS

The prevalence of anemia was 36.7%. Female participants were more frequently anemic than male participants (47.4% versus 18.2%, P = 0.024). Anemic patients had a lower albumin level (31.3 versus 33.4 g/L, P = 0.019) and a higher erythrocyte sedimentation rate (29.6 versus 16.0 mm/h, P = 0.005) and were more often malnourished (81.8% versus 44.7%, P = 0.005) than non-anemic patients. Hemoglobin correlated with prealbumin (rho = 0.338, P = 0.008) and albumin (rho = 0.250, P = 0.054) levels, but negatively with age (rho = -0.310, P = 0.016) and erythrocyte sedimentation rate (rho = -0.412, P < 0.001). In the multivariate analysis, erythrocyte sedimentation rate and nutritional status were significant predictors of hemoglobin (R(2) = 34.0%).

CONCLUSION

This cross-sectional analysis provides evidence of anemia in 36.7% of patients hospitalized at the Landspitali-University Hospital in Reykjavik and shows an association among anemia, deteriorated nutritional status, and inflammation. Future prospective studies are needed to assess the efficacy of adjuvant nutritional support to stabilize or improve nutritional status including anemia in hospitalized elderly.

Role of leptin in reverse epidemiology in chronic kidney disease

Leptin is mainly produced by adipocytes and metabolized in the kidney. Leptin is taken up into the central nervous system by a saturable transport system, and controls appetite in rodents and in healthy subjects. Leptin acts on peripheral tissue and increases the inflammatory response by stimulating the production of tumor necrosis factor alpha, interleukin-6 and interleukin-12. In healthy humans, serum leptin concentration is related to the size of adipose tissue mass in the body. The majority of obese subjects have inappropriately high levels of circulating plasma leptin concentrations, indicating leptin resistance. In healthy subjects increased leptin concentration constitutes a biomarker for increased cardiovascular risk. On the other hand, a recent prospective long-term study in patients with chronic kidney disease stage 5 on hemodialysis therapy showed that reduced serum leptin concentration is an independent risk factor for mortality in these patients.