Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate. Kidney Int. 2014;86:1031-1038. [PMID: 24694986 DOI: 10.1038/ki.2014.83]

Patient Perception of Plant Based Diets for Kidney Disease

OBJECTIVE

Plant-based diets can delay the progression of chronic kidney disease (CKD) and help manage complications and comorbid conditions such as hypertension, acidosis, diabetes, and cardiovascular disease. The objective of this study was to understand nephrology patients' familiarity, perception, and use of plant-based diets.

DESIGN & METHODS

A survey was shared via the National Kidney Foundation's social media channels. Analysis included 844 responses. Survey items were evaluated with descriptive statistics. Differences across items were determined using chi-square tests.

RESULTS

Most respondents were 61-70 years of age (26.7%, n = 225), female (56.5%, n = 477) and achieved a Bachelor's or advanced degree (49.9%, n = 421). The majority of respondents suffered from nondialysis-dependent CKD (34%) or received a kidney transplant (34%). About half (45%) of respondents were familiar with plant-based diets and most (58%) were aware that plant-based diets can improve CKD. Twenty-two percent reported following some version of a vegetarian diet, and 29% reported "eating less meat". Respondents were not confident (Mdn = 2, IQR = 2, on a scale of 1-5) in their ability to plan a balanced plant-based meal, and were moderately confident that a plant-based diet could help blood pressure (Mdn = 3, IQR = 2) and slow progression of CKD (Mdn = 3, IGR = 2). Family eating preference, meal planning skills, preference for meat, figuring out what is healthy to eat, food cost, time constraints, and ease of cooking were rated as equal barriers to following a plant-based diet (Mdn = 3). A sample meal plan, individual counseling session with a Registered Dietitian Nutritionist (RDN), handouts, and cooking classes were resources rated most helpful to transition to a plant-based diet (Mdn = 4).

CONCLUSION

Approximately half of respondents were aware that plant-based diets can be beneficial for CKD. Many patients are following a vegetarian or plant-based eating pattern. More research should be done to see how effective RDNs are in educating and moving patients toward a plant-based eating pattern, as they are an underutilized resource in the CKD population.

Is Losing Weight Worth Losing Your Kidney: Keto Diet Resulting in Renal Failure

Keto diet is defined as a high-fat, adequate-protein, and low-carbohydrate nutrition which forces the body to burn fats and use an alternative metabolic fuel resource by stimulating endogenous ketone production. The standard range of ketones in ketosis is up to 3.00mmol/L, and anything beyond this level can result in serious medical conditions. This diet's most common and easily reversible consequences are constipation, low-grade acidosis, hypoglycemia, kidney stones, and increased lipid in the blood. We present a case of a 36-year-old female who presented with pre-renal azotemia after starting a keto diet regimen.

The Role of Dietary Potassium in the Cardiovascular Protective Effects of Plant-Based Diets

Dietary intervention is an essential factor in managing a multitude of chronic health conditions such as cardiovascular and chronic kidney disease. In recent decades, there has been a host of research suggesting the potential benefit of plant-based diets in mitigating the health outcomes of these conditions. Plant-based diets are rich in vegetables and fruits, while limiting processed food and animal protein sources. The underlying physiological mechanism involves the interaction of several macronutrients and micronutrients such as plant protein, carbohydrates, and dietary potassium. Specifically, plant-based foods rich in potassium provide cardiorenal protective effects to include urinary alkalization and increased sodium excretion. These diets induce adaptive physiologic responses that improve kidney and cardiovascular hemodynamics and improve overall metabolic health. A shift toward consuming plant-based diets even in subjects with cardiorenal decrements may reduce their morbidity and mortality. Nonetheless, randomized controlled trials are needed to confirm the clinical benefits of plant-based diets.

The mechanisms of alkali therapy in targeting renal diseases

Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function and treatments aiming at stabilizing or slowing its progression may avoid or delay the necessity of kidney replacement therapy and the increased mortality associated with reduced kidney function. Metabolic acidosis, and less severe stages of the acid stress continuum, are common consequences of CKD and some interventional studies support that its correction slows the progression to end-stage kidney disease. This correction can be achieved with mineral alkali in the form of bicarbonate or citrate salts, ingestion of diets with fewer acid-producing food components or more base-producing food components, or a pharmacological approach. In this mini-review article, we summarize the potential mechanisms involved in the beneficial effects of alkali therapy. We also discuss the perspectives in the field and challenges that must be overcome to advance our understanding of such mechanisms.

Sodium bicarbonate for kidney transplant recipients with metabolic acidosis in Switzerland: a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial

BACKGROUND

Metabolic acidosis is common in kidney transplant recipients and is associated with declining graft function. Sodium bicarbonate treatment effectively corrects metabolic acidosis, but no prospective studies have examined its effect on graft function. Therefore, we aimed to test whether sodium bicarbonate treatment would preserve graft function and slow the progression of estimated glomerular filtration rate (GFR) decline in kidney transplant recipients.

METHODS

The Preserve-Transplant Study was a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial at three University Hospitals in Switzerland (Zurich, Bern, and Geneva), which recruited adult (aged ≥18 years) male and female long-term kidney transplant recipients if they had undergone transplantation more than 1 year ago. Key inclusion criteria were an estimated GFR between 15 mL/min per 1·73 m2 and 89 mL/min per 1·73 m2, stable allograft function in the last 6 months before study inclusion (<15% change in serum creatinine), and a serum bicarbonate of 22 mmol/L or less. We randomly assigned patients (1:1) to either oral sodium bicarbonate 1·5-4·5 g per day or matching placebo using web-based data management software. Randomisation was stratified by study centre and gender using a permuted block design to guarantee balanced allocation. We did multi-block randomisation with variable block sizes of two and four. Treatment duration was 2 years. Acid-resistant soft gelatine capsules of 500 mg sodium bicarbonate or matching 500 mg placebo capsules were given at an initial dose of 500 mg (if bodyweight was <70 kg) or 1000 mg (if bodyweight was ≥70 kg) three times daily. The primary endpoint was the estimated GFR slope over the 24-month treatment phase. The primary efficacy analyses were applied to a modified intention-to-treat population that comprised all randomly assigned participants who had a baseline visit. The safety population comprised all participants who received at least one dose of study drug. The trial is registered with ClinicalTrials.gov, NCT03102996.

FINDINGS

Between June 12, 2017, and July 10, 2019, 1114 kidney transplant recipients with metabolic acidosis were assessed for trial eligibility. 872 patients were excluded and 242 were randomly assigned to the study groups (122 [50%] to the placebo group and 120 [50%] to the sodium bicarbonate group). After secondary exclusion of two patients, 240 patients were included in the intention-to-treat analysis. The calculated yearly estimated GFR slopes over the 2-year treatment period were a median -0·722 mL/min per 1·73 m2 (IQR -4·081 to 1·440) and mean -1·862 mL/min per 1·73 m2 (SD 6·344) per year in the placebo group versus median -1·413 mL/min per 1·73 m2 (IQR -4·503 to 1·139) and mean -1·830 mL/min per 1·73 m2 (SD 6·233) per year in the sodium bicarbonate group (Wilcoxon rank sum test p=0·51; Welch t-test p=0·97). The mean difference was 0·032 mL/min per 1·73 m2 per year (95% CI -1·644 to 1·707). There were no significant differences in estimated GFR slopes in a subgroup analysis and a sensitivity analysis confirmed the primary analysis. Although the estimated GFR slope did not show a significant difference between the treatment groups, treatment with sodium bicarbonate effectively corrected metabolic acidosis by increasing serum bicarbonate from 21·3 mmol/L (SD 2·6) to 23·0 mmol/L (2·7) and blood pH from 7·37 (SD 0·06) to 7·39 (0·04) over the 2-year treatment period. Adverse events and serious adverse events were similar in both groups. Three study participants died. In the placebo group, one (1%) patient died from acute respiratory distress syndrome due to SARS-CoV-2 and one (1%) from cardiac arrest after severe dehydration following diarrhoea with hypotension, acute kidney injury, and metabolic acidosis. In the sodium bicarbonate group, one (1%) patient had sudden cardiac death.

INTERPRETATION

In adult kidney transplant recipients, correction of metabolic acidosis by treatment with sodium bicarbonate over 2 years did not affect the decline in estimated GFR. Thus, treatment with sodium bicarbonate should not be generally recommended to preserve estimated GFR (a surrogate marker for graft function) in kidney transplant recipients with chronic kidney disease who have metabolic acidosis.

FUNDING

Swiss National Science Foundation.

Plant-Dominant Low Protein Diet: A Potential Alternative Dietary Practice for Patients with Chronic Kidney Disease

Dietary protein restriction has long been a cornerstone of nutritional therapy for patients with chronic kidney diseases (CKD). However, the recommended amount of dietary protein intake is different across guidelines. This is partly because previous randomized controlled trials have reported conflicting results regarding the efficacy of protein restriction in terms of kidney outcomes. Interestingly, a vegetarian, very low protein diet has been shown to reduce the risk of kidney failure among patients with advanced CKD, without increasing the incidence of hyperkalemia. This finding suggests that the source of protein may also influence the kidney outcomes. Furthermore, a plant-dominant low-protein diet (PLADO) has recently been proposed as an alternative dietary therapy for patients with CKD. There are several potential mechanisms by which plant-based diets would benefit patients with CKD. For example, plant-based diets may reduce the production of gut-derived uremic toxins by increasing the intake of fiber, and are useful for correcting metabolic acidosis and hyperphosphatemia. Plant proteins are less likely to induce glomerular hyperfiltration than animal proteins. Furthermore, plant-based diets increase magnesium intake, which may prevent vascular calcification. More evidence is needed to establish the efficacy, safety, and feasibility of PLADO as a new adjunct therapy in real-world patients with CKD.

Sodium zirconium cyclosilicate and metabolic acidosis: Potential mechanisms and clinical consequences

Metabolic acidosis is frequent in chronic kidney disease (CKD) and is associated with accelerated progression of CKD, hypercatabolism, bone disease, hyperkalemia, and mortality. Clinical guidelines recommend a target serum bicarbonate ≥ 22 mmol/L, but metabolic acidosis frequently remains undiagnosed and untreated. Sodium zirconium cyclosilicate (SZC) binds potassium in the gut and is approved to treat hyperkalemia. In clinical trials with a primary endpoint of serum potassium, SZC increased serum bicarbonate, thus treating CKD-associated metabolic acidosis. The increase in serum bicarbonate was larger in patients with more severe pre-existent metabolic acidosis, was associated to decreased serum urea and was maintained for over a year of SZC therapy. SZC also decreased serum urea and increased serum bicarbonate after switching from a potassium-binding resin in normokalemic individuals. Mechanistically, these findings are consistent with SZC binding the ammonium ion (NH₄⁺) generated from urea by gut microbial urease, preventing its absorption and, thus, preventing the liver regeneration of urea and promoting the fecal excretion of H⁺. This mechanism of action may potentially result in benefits dependent on corrected metabolic acidosis (e.g., improved well-being, decreased catabolism, improved CKD mineral bone disorder, better control of serum phosphate, slower progression of CKD) and dependent on lower urea levels, such as decreased protein carbamylation. A roadmap is provided to guide research into the mechanisms and clinical consequences of the impact of SZC on serum bicarbonate and urate.

Diabetic kidney disease in type 2 diabetes: a consensus statement from the Swiss Societies of Diabetes and Nephrology

Diabetic kidney disease is highly prevalent in patients with type 2 diabetes and is a major cause of end-stage renal disease in Switzerland. Patients with diabetic kidney disease are among the most complex patients in diabetes care. They require a multifactorial and multidisciplinary approach with the goal to slow the decline in glomerular filtration rate (GFR) and cardiovascular morbidity. With this consensus we propose an evidence-based guidance to health care providers involved in the care of type 2 diabetic patients with diabetic kidney disease.First, there is a need to increase physician awareness and improve screening for diabetic kidney disease as early intervention may improve clinical outcomes and the financial burden. Evaluation of estimated GFR (eGFR) and spot urine albumin/creatinine ratio is recommended at least annually. Once it is diagnosed, glucose control and optimisation of blood pressure control with renin-angiotensin system blockers have been recommended as mainstay management of diabetic kidney disease for more than 20 years. Recent, high quality randomised controlled trials have shown that sodium-glucose cotransporter-2 (SGLT2) inhibition slows eGFR decline and cardiovascular events beyond glucose control. Likewise, mineralocorticoid receptor antagonism with finerenone has cardiorenal protective effects in diabetic kidney disease. Glucagon-like peptide-1 (GLP1) receptor agonists improve weight loss if needed, and decrease albuminuria and cardiovascular morbidity. Lipid control is also important to decrease cardiovascular events. All these therapies are included in the treatment algorithms proposed in this consensus. With advancing kidney failure, other challenges may rise, such as hyperkalaemia, anaemia and metabolic acidosis, as well as chronic kidney disease-mineral and bone disorder. These different topics and treatment strategies are discussed in this consensus. Finally, an update on diabetes management in renal replacement therapy such as haemodialysis, peritoneal dialysis and renal transplantation is provided. With the recent developments of efficient therapies for diabetic kidney disease, it has become evident that a consensus document is necessary. We are optimistic that it will significantly contribute to a high-quality care for patients with diabetic kidney disease in Switzerland in the future.

Paradigm shift in lifestyle modification for solitary kidney after donor nephrectomy

PURPOSE OF REVIEW

Living donor kidney transplantation potentially leads to long-term complications including chronic kidney disease, end-stage kidney disease, elevated blood pressure, and pregnancy-associated hypertension. Given living donors generally do not have underlying medical conditions, lifestyle modifications, particularly dietary interventions may prevent those complications and improve their health outcomes.

RECENT FINDINGS

Glomerular hyperfiltration occurs as physiologic adaptation during an initial postdonor nephrectomy period. In the long-term, these adaptations may become pathologic consequences resulting from hyperfiltration-mediated kidney injury and ultimately secondary focal segmental glomerulosclerosis in the solitary kidney. Dietary interventions to slow a decline in kidney function include low protein intake of <0.8 g/kg/day and low sodium consumption of 2-4 g/day as well as certain health dietary patterns. There is no evidence regarding the quantity and quality of protein that can be recommended for living kidney donors and the same for sodium. Plant Dominant (PLADO) diets, Dietary Approaches to Stop Hypertension (DASH), Mediterranean, and vegetarian diets may be favorable for living kidney donors with solitary kidney but the evidence is still lacking.

SUMMARY

Although dietary interventions may provide benefits and kidney health for living kidney donors, further studies including clinical trials are required to incorporate them into clinical practice guidelines.

Dietary Acid Load and Predialysis Serum Bicarbonate Levels in Patients With End-Stage Renal Disease

OBJECTIVES

Maintaining the predialysis serum bicarbonate at a recommended level is critical in patients undergoing hemodialysis. Therefore, the present study investigated the association between dietary acid load (DAL) and serum predialysis bicarbonate levels in patients with end-stage renal disease.

METHODS

Adult patients undergoing hemodialysis were enrolled in this cross-sectional study. Diet was assessed using a semiquantitative food frequency questionnaire. DAL was calculated with 2 validated indices: potential renal acid load (PRAL) and net endogenous acid production (NEAP). Values regarding predialysis serum bicarbonate level and serum electrolytes were obtained from the participant's medical records. The multiple linear regression analysis was used to determine the association between DAL indices and predialysis serum bicarbonate level.

RESULTS

The number of hemodialysis patients eligible for this study was 122. The participants' mean age and body mass index was 57.14 ± 3.8 years and 25.2 ± 4.9 kg/m², respectively. About 65.6% of participants were male. The mean serum levels of predialysis bicarbonate were 21.59 ± 3.1 mEq/L. Also, 47.5% of patients had predialysis serum bicarbonate levels below the recommended value. The mean values of PRAL and NEAP were -2.8 ± 7.48 and 42.7 ± 10.1 mEq/day, respectively. PRAL significantly and inversely predicted predialysis serum bicarbonate level independent of covariates (standardized β = -0.38; P < .001). Also, NEAP was independently and inversely associated with predialysis bicarbonate level (standardized β = -0.40; P < .001). Consuming vegetables such as lettuce, tomato, cucumber, spinach, and dried fruits as well as low-fat milk, plain yogurt, and cream cheese were positively correlated to predialysis serum bicarbonate level. However, the canned tuna had a negative correlation with the predialysis serum bicarbonate.

CONCLUSIONS

The study's findings showed that the lower DAL was associated with higher predialysis serum bicarbonate levels in patients with end-stage renal disease. Due to the cross-sectional nature of the present study, prospective cohorts or well-controlled clinical trials are needed to confirm our result.

Longitudinal trajectory of acidosis and mortality in acute kidney injury requiring continuous renal replacement therapy

BACKGROUND

Acidosis frequently occurs in severe acute kidney injury (AKI), and continuous renal replacement therapy (CRRT) can control this pathologic condition. Nevertheless, acidosis may be aggravated; thus, monitoring is essential after starting CRRT. Herein, we addressed the longitudinal trajectory of acidosis on CRRT and its relationship with worse outcomes.

METHODS

The latent growth mixture model was applied to classify the trajectories of pH during the first 24 hours and those of C-reactive protein (CRP) after 24 hours on CRRT due to AKI (n = 1815). Cox proportional hazard models were used to calculate hazard ratios of all-cause mortality after adjusting multiple variables or matching their propensity scores.

RESULTS

The patients could be classified into 5 clusters, including the normally maintained groups (1st cluster, pH = 7.4; and 2nd cluster, pH = 7.3), recovering group (3rd cluster with pH values from 7.2 to 7.3), aggravating group (4th cluster with pH values from 7.3 to 7.2), and ill-being group (5th cluster, pH < 7.2). The pH clusters had different trends of C-reactive protein (CRP) after 24 hours; the 1st and 2nd pH clusters had lower levels, but the 3rd to 5th pH clusters had an increasing trend of CRP. The 1st pH cluster had the best survival rates, and the 3rd to 5th pH clusters had the worst survival rates. This survival difference was significant despite adjusting for other variables or matching propensity scores.

CONCLUSIONS

Initial trajectories of acidosis determine subsequent worse outcomes, such as mortality and inflammation, in patients undergoing CRRT due to AKI.

Diet and Proteinuria: State of Art

Proteinuria is a broad term used to describe the pathological presence of proteins, including albumin, globulin, Bence-Jones protein, and mucoprotein in the urine. When persistent, proteinuria is a marker of kidney damage and represents a reliable predictor of the risk of progression of renal failure. Medical nutrition therapy is imperative for patients with proteinuria because it may slow the progression of renal disease. The aim of this review is to explore different nutritional approaches in the management of proteinuria and their influence on pathophysiological processes. As such, protein restriction is the main dietary intervention. Indeed, other management approaches are frequently used to reduce it regarding micro and macronutrients, but also the dietary style. Among these, the nutritional approach represents one of the most used and controversial interventions and the studies rarely take the form of randomized and controlled trials. With this work we aspire to analyze current clinical knowledge of how nutrition could influence proteinuria, potentially representing a useful tool in the management of proteinuric nephropathy.

Contributions of obesity to kidney health and disease: insights from Mendelian randomization and the human kidney transcriptomics

AIMS

Obesity and kidney diseases are common complex disorders with an increasing clinical and economic impact on healthcare around the globe. Our objective was to examine if modifiable anthropometric obesity indices show putatively causal association with kidney health and disease and highlight biological mechanisms of potential relevance to the association between obesity and the kidney.

METHODS AND RESULTS

We performed observational, one-sample, two-sample Mendelian randomization (MR) and multivariable MR studies in ∼300 000 participants of white-British ancestry from UK Biobank and participants of predominantly European ancestry from genome-wide association studies. The MR analyses revealed that increasing values of genetically predicted body mass index and waist circumference were causally associated with biochemical indices of renal function, kidney health index (a composite renal outcome derived from blood biochemistry, urine analysis, and International Classification of Disease-based kidney disease diagnoses), and both acute and chronic kidney diseases of different aetiologies including hypertensive renal disease and diabetic nephropathy. Approximately 13-16% and 21-26% of the potentially causal effect of obesity indices on kidney health were mediated by blood pressure and type 2 diabetes, respectively. A total of 61 pathways mapping primarily onto transcriptional/translational regulation, innate and adaptive immunity, and extracellular matrix and metabolism were associated with obesity measures in gene set enrichment analysis in up to 467 kidney transcriptomes.

CONCLUSIONS

Our data show that a putatively causal association of obesity with renal health is largely independent of blood pressure and type 2 diabetes and uncover the signatures of obesity on the transcriptome of human kidney.

Chronic Sub-Clinical Systemic Metabolic Acidosis - A Review with Implications for Clinical Practice

When arterial serum pH remains near the lower pH limit of 7.35 for protracted periods of time, a low-grade, sub-clinical form of acidosis results, referred to in this review as chronic, sub-clinical, systemic metabolic acidosis (CSSMA). This narrative review explores the scientific basis for CSSMA, its consequences for health, and potential therapeutic interventions. The major etiology of CSSMA is the shift away from the ancestral, alkaline diet which was rich in fruit and vegetables, toward the contemporary, acidogenic 'Westernized' diet characterized by higher animal protein consumption and lack of base forming minerals. Urine pH is reduced with high dietary acid load and may be a convenient marker of CSSMA. Evidence suggests further that CSSMA negatively influences cortisol levels potentially contributing significantly to the pathophysiology thereof. Both CSSMA and high dietary acid load are associated with the risk and prognosis of various chronic diseases. Clinical trials show that CSSMA can be addressed successfully through alkalizing the diet by increasing fruit and vegetable intake and/or supplementing with alkaline minerals. This review confirms the existence of a significant body of evidence regarding this low-grade form of acidosis as well as evidence to support its diverse negative implications for health, and concludes that CSSMA is a condition warranting further research.

Observational and clinical evidence that plant-based nutrition reduces dietary acid load

Contemporary diets in Western countries are largely acid-inducing and deficient in potassium alkali salts, resulting in low-grade metabolic acidosis. The chronic consumption of acidogenic diets abundant in animal-based foods (meats, dairy, cheese and eggs) poses a substantial challenge to the human body's buffering capacities and chronic retention of acid wherein the progressive loss of bicarbonate stores can cause cellular and tissue damage. An elevated dietary acid load (DAL) has been associated with systemic inflammation and other adverse metabolic conditions. In this narrative review, we examine DAL quantification methods and index observational and clinical evidence on the role of plant-based diets, chiefly vegetarian and vegan, in reducing DAL. Quantitation of protein and amino acid composition and of intake of alkalising organic potassium salts and magnesium show that plant-based diets are most effective at reducing DAL. Results from clinical studies and recommendations in the form of expert committee opinions suggest that for a number of common illnesses, wherein metabolic acidosis is a contributing factor, the regular inclusion of plant-based foods offers measurable benefits for disease prevention and management. Based on available evidence, dietary shifts toward plant-based nutrition effectively reduces dietary-induced, low-grade metabolic acidosis.

New mechanisms for the kidney-protective effect of alkali in chronic kidney disease

Worldwide, more than one in ten adults are estimated to have chronic kidney disease (CKD). As CKD progresses, both the cost of treatment and associated risk of morbidity and mortality increase exponentially. As such, there is a great need for therapies that effectively slow CKD progression. Evidence from several small clinical trials indicates that alkali therapy may slow the rate of CKD progression. The biological mechanisms underlying this protective effect, however, remain unknown. In their recently published manuscript, Pastor Arroyo et al. (Clin Sci (Lond) (2022) 136(8): https://doi.org/10.1042/CS20220095) demonstrate that the alkali sodium bicarbonate protects against loss of renal function in a crystal nephropathy model in mice. Using unbiased approaches in both mice and human tissue, the authors go on to identify two novel mechanisms that may underly this protection. The first pathway is through promoting pathways of cell metabolism, which they speculate helps the remaining functional nephrons adapt to the greater metabolic needs required to maintain kidney filtration. The second pathway is by restoration of α-Klotho levels, which may limit the expression of adhesion molecules in the injured kidney. This, the authors speculate, may prevent inflammation from driving the functional decline of the kidney. Identifying these novel pathways represents an important step forward harnessing the potential benefits of alkali therapy in CKD.

Fibre Intake in Chronic Kidney Disease: What Fibre Should We Recommend?

Chronic kidney disease (CKD) is a major global health problem that challenges all patients' healthcare needs. Fibre consumption benefits kidney patients by acting preventively on associated risk factors, improving intestinal microbiota composition or reducing metabolic acidosis and inflammation. In this review, we focus on increasing fibre consumption and the quality of fibre to recommend, in addition to increasing the consumption of foods that naturally have it in their design, that can resort to fortified foods or fibre supplements. The Western nutritional practice, which is low in fibre and rich in animal proteins, saturated fats, sodium, and sugar, increases the risk of mortality in these patients. On the contrary, patterns with higher consumption of fibre and vegetable proteins, such as the Mediterranean, vegetarian, or Plant dominant low protein diet (PLADO), seem to have a preventive effect on the associated risk factors and influence CKD progression. Until now, the use of fibre supplements has not achieved an evident impact on clinical results. Fibre-rich foods contain other nutrients that reduce cardiovascular risk. Promoting diets richer in vegetables and guaranteeing adequate energy and protein intake is a challenge for the multidisciplinary teams involved in the standard of care for CKD.

Etiology, Comorbidities, and Rate of Progression of Pediatric Chronic Kidney Disease: A Cohort Study

OBJECTIVES

To evaluate the etiology of pediatric chronic kidney disease (CKD), assess comorbidities, and identify rate of progression of CKD and its risk factors.

METHODS

Children aged 2-18 y with the Kidney Disease Improving Global Outcome (KDIGO) CKD stages 2-4 were enrolled. The etiology of CKD and its comorbidities were recorded. Kaplan-Meier survival curves were used to analyze the time to progression of CKD.

RESULTS

Of the 131 patients enrolled, CKD stages 2, 3a, 3b, and 4 constituted 62 (47.3%), 17 (13%), 26 (19.8%), and 26 (19.8%), respectively. At the last follow-up [at median (IQR) 24 (12, 30) mo], the number of children in CKD stages 2, 3a, 3b, 4 and 5 were 48 (36.6%), 16 (12.2%), 23 (17.6%), 28 (21.4%), and 16 (12.2%), respectively. Etiologies of CKD included obstructive uropathy [48 (36.6%)], chronic glomerular disease [19 (14.5%)], reflux nephropathy [14 (10.7%)] and cystic renal disease [11 (8.3%)]. Comorbidities during follow-up included CKD-MBD [87 (66.4%)], metabolic acidosis [95 (72.5%)], hypertension [88 (67.1%)], growth retardation [69 (52.6%)], and anemia [63 (48.1%)]. The number of patients with metabolic acidosis, hypertension, MBD and anemia in CKD stage 2 were 27 (56%), 26 (54.2%), 24 (50%), 15 (30%), respectively. The median (IQR) rate of decline in eGFR was 3.3 (2, 4.6) mL/min/1.73 m²/y. On multivariable analysis, proteinuria [hazard ratio 3.5 (95% CI 1.4, 8.8) p = 0.01] and hyperphosphatemia [hazard ratio 2.2 (95% CI 1.1, 4.3) p = 0.03] were significant predictors for progression of CKD.

CONCLUSIONS

Even the earlier stages of CKD had significant comorbidities. The median decline in eGFR was 3.3 mL/min/1.73 m²/y. Proteinuria and hyperphosphatemia were the risk factors for progression of CKD.

Primary Medical Care Integrated with Healthy Eating and Healthy Moving is Essential to Reduce Chronic Kidney Disease Progression

Increasing adverse outcomes in patients with chronic kidney disease reflect growth of patients with early-stage chronic kidney disease and their increasing per population rates of these outcomes. Progression of chronic kidney disease, more than current level of kidney function, is the primary driver of adverse chronic kidney disease-related outcomes. Racial/ethnic minorities progress faster to end-stage kidney disease with greater risk for adverse outcomes. Diabetes and hypertension cause two-thirds of end-stage kidney disease, for which primary medical care integrated with healthy eating and increased physical activity (healthy moving) slows chronic kidney disease progression. Patients with early-stage chronic kidney disease are appropriately managed by primary care practices but most lack infrastructure to facilitate this integration that reduces adverse chronic kidney disease-related outcomes. Individuals of low socioeconomic status are at greater chronic kidney disease risk, and flexible regulatory options in Medicaid can fund infrastructure to facilitate healthy eating and healthy moving integration with primary medical care. This integration promises to reduce chronic kidney disease-related adverse outcomes, disproportionately in racial/ethnic minorities, and thereby reduce chronic kidney disease-related health disparities.

A Novel Approach for Managing Protein-Energy Wasting in People With Kidney Failure Undergoing Maintenance Hemodialysis: Rationale and Call for Trials

Protein-energy wasting (PEW) is a unique presentation of protein-energy malnutrition in people with kidney disease that is characterized by body protein catabolism exceeding anabolism. PEW is especially common in patients undergoing maintenance hemodialysis (HD) treatment. Dietary guidelines for managing PEW in HD patients primarily focus on protein adequacy and typically promote the intake of animal-based protein foods. Although intake of protein and essential amino acids is important for protein synthesis, the emphasis on protein adequacy largely fails to address-and may actually exacerbate-many of the root causes of PEW. This perspective examines the dietary determinants of PEW in people undergoing HD treatment, with an emphasis on upstream disease-related factors that reduce dietary protein utilization and impair dietary intakes. From this, we present a theoretical diet model for managing PEW that includes etiology-based dietary strategies to address barriers to intake and treat disease-related factors, as well as supportive dietary strategies to promote adequate energy and protein intakes. Given the complexity of diet-disease interactions in the pathogenesis of PEW, and its ongoing burden in HD patients, interventional trials are urgently needed to evaluate alternative diet therapy approaches for PEW in this population.

The Importance of Recognizing and Addressing the Spectrum of Acid Stress

Acid accumulation sufficient to reduce plasma bicarbonate concentration, thereby recognized as chronic metabolic acidosis, harms bones and muscles and appears to enhance progression of CKD. Evolving evidence supports that progressive acid accumulation that is not enough to cause chronic metabolic acidosis nevertheless has deleterious effects. Measurable acid retention without reduced plasma bicarbonate concentration, called eubicarbonatemic acidosis, also appears to cause kidney injury and exacerbate CKD progression. Furthermore, chronic engagement of mechanisms to mitigate the ongoing acid challenge of net acid-producing diets of developed societies also appears to be deleterious, including for kidney health. This review challenges clinicians to consider the growing evidence for a spectrum of acid-accumulation disorders that include lesser degrees of acid accumulation than metabolic acidosis yet are harmful. Further research will develop clinically useful tools to identify individuals suffering from these earlier stages of acid stress and determine if the straightforward and comparatively inexpensive intervention of dietary acid reduction relieves or eliminates the harm they appear to cause.

Management of Metabolic Acidosis in Chronic Kidney Disease: Past, Present, and Future Direction

Chronic kidney disease (CKD) is a major global epidemic associated with increased morbidity and mortality. Despite the effectiveness of kidney protection strategies of hypertension, diabetes, and lipid control and use of newer hypoglycemic agents and anti-angiotensin II drugs, the nephropathy in CKD continues unabated toward irreversible kidney failure. Thus, interventions targeting modifiable risk factors in CKD such as metabolic acidosis (MA) are needed. Acid reduction with sodium-based alkali has been shown to be an effective kidney-protection strategy for patients with CKD and reduced glomerular filtration rate (GFR). Small-scale studies reveal diets emphasizing ingestion of plant-sourced over animal-sourced protein reduce dietary acid, improve MA, and slow further nephropathy progression in patients with CKD and reduced GFR. Additionally, veverimer, an investigational, nonabsorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as a novel treatment for MA. As further studies define how to best use these interventions for kidney protection, clinicians must become aware of their potential utility in the management of patients with CKD. The aim of the present review is to explore the various intervention strategies that increase or normalize serum [HCO₃^-] in patients with CKD-associated MA or low normal serum [HCO₃^-] that may further slow progression of CKD.

Potassium and fiber: a controversial couple in the nutritional management of children with chronic kidney disease

BACKGROUND

Fruit and vegetable intake is commonly discouraged in children with chronic kidney disease (CKD) to avoid hyperkalemia. However, direct evidence in support of this widespread practice is lacking. Furthermore, the resultant restricted fiber exposure may deprive CKD patients from potential health benefits associated with the latter. Therefore, we investigated associations between dietary potassium intake, fiber intake, and serum potassium levels in pediatric CKD.

METHODS

This study is a longitudinal analysis of a 2-year, prospective, multi-institutional study, following children with CKD at 3-month intervals. At each visit, dietary potassium and fiber intake were assessed, using 24-h recalls and 3-day food records. On the same occasion, serum potassium concentrations were determined. Associations between dietary potassium intake, dietary fiber intake, and serum potassium concentrations were determined using linear mixed models.

RESULTS

Fifty-two CKD patients (7 transplant recipients, none on dialysis) aged 9 [4;14] years with an estimated glomerular filtration rate (eGFR) of 49 [25;68] mL/min/1.73 m² were included. For every g/day decrease in dietary potassium intake, the estimated mean daily fiber intake was 5.1 g lower (95% confidence interval (CI), 4.3-5.9 g/day; p < 0.001). Neither dietary potassium intake (p = 0.40) nor dietary fiber intake (p = 0.43) was associated with circulating potassium in a model adjusted for time point, eGFR, treatment with a renin-angiotensin-aldosterone system blocker, serum bicarbonate concentration, and body surface area.

CONCLUSIONS

Dietary potassium and fiber intake are closely related but were not associated with circulating potassium levels in pediatric CKD. A higher-resolution version of the graphical abstract is available as Supplementary information.

Acid-Mediated Kidney Injury Across the Spectrum of Metabolic Acidosis

Metabolic acidosis affects about 15% of patients with chronic kidney disease. As kidney function declines, the kidneys progressively fail to eliminate acid, primarily reflected by a decrease in ammonium and titratable acid excretion. Several studies have shown that the net acid load remains unchanged in patients with reduced kidney function; the ensuing acid accumulation can precede overt metabolic acidosis, and thus, indicators of urinary acid or potential base excretion, such as ammonium and citrate, may serve as early signals of impending metabolic acidosis. Acid retention, with or without overt metabolic acidosis, initiates compensatory responses that can promote tubulointerstitial fibrosis via intrarenal complement activation and upregulation of endothelin-1, angiotensin II, and aldosterone pathways. The net effect is a cycle between acid accumulation and kidney injury. Results from small- to medium-sized interventional trials suggest that interrupting this cycle through base administration can prevent further kidney injury. While these findings inform current clinical practice guidelines, large-scale clinical trials are still necessary to prove that base therapy can limit chronic kidney disease progression or associated adverse events.

Regulation of Acid-Base Balance in Patients With Chronic Kidney Disease

Normallly the kidneys handle the daily acid load arising from net endogenous acid production from the metabolism of ingested animal protein (acid) and vegetables (base). With chronic kidney disease, reduced acid excretion by the kidneys is primarily due to reduced ammonium excretion such that when acid excertion falls below acid porduction, acid accumulation occurs. With even mild reductions in glomerular filtration rate (60 to 90 ml/min), net acid excretion may fall below net acid production resulting in acid retention which may be initially sequestered in interstitial compartments in the kidneys, bones, and muscles resulting in no fall in measured systemic bicarbonate levels (eubicarbonatemic metabolic acidosis). With greater reductions in kidney function, the greater quantities of acid retained spillover systemically resulting in low pH (overt metabolic acidosis). The evaluation of acid-base balance in patients with CKD is complicated by the heterogeneity of clinical acid-base disorders and by the eubicarbonatemic nature of the early phase of acid retention. If supported by more extensive studies, blood gas analyses to confirm the acid-base disorder and newer ways for assessing the presence of acidosis such as urinary citrate measurements may become routine tools to evaluate and treat acid-base disorders in individuals with CKD.

New approaches in the nutritional treatment of advanced chronic kidney disease

INTRODUCTION

Patients with advanced chronic kidney disease (ACKD) have a high prevalence of malnutrition. The dietary restrictions that we usually apply in terms of macro and micronutrients force our patients to follow dietary guidelines that deviate from healthy patterns.

OBJETIVES

To determine if a personalized nutritional intervention program, minimizing the usual restrictions would be justified in case it improved the evolution of kidney disease compared to standard treatment.

SECUNDARY OBJETIVES

To determine changes in nutrient intakes and in anthropometric and biochemical parameters, as well as quantify episodes of hyperkalemia.

MATERIAL AND METHODS

A single-center, randomized and controlled educational intervention clinical trial was conduct in patients from the ERCA outpatients clinic at the Complejo Hospitalario Universitario de Albacete. 75 patients were included, assigning 35 to a Control group and 40 to the Intervention group with 1-year follow-up. The nutritional status was determined using anthropometric data, body composition by Bioimpedance, blood and urine biochemical parameters and a 24-h recall questionnaire. The nutritional intervention was carried out in three different ways: individual, collective and telephone recall.

RESULTS

At the beginning of the study, the BMI showed a situation of weight excess with a mean of 28.83 kg/m² (5.4) in men and 26.96 kg/m² (4.09) in women. 70% of our patients had overweight. The abdominal circumference was 105.3 cm (10.2) and 92.3 cm (13.7) for men and women respectively without significant changes throughout the study. The percentage of fat mass (FM) was high in both groups for men and women throughout the study. We did not find biochemical parameters of malnutrition and only significant differences were observed in glomerular filtration rate (GFR), which increased in the intervention group. No patient presented any episodes of hyperkalemia during the study. The energy intake in both groups showed an inadequate distribution of macronutrients with a poor intake of carbohydrates (CH) that was supplemented with an excess of fat. In the case of micronutrients, we did observe an increase in potassium and fiber intakes with a decrease in sodium and phosphorus in the intervention group.

CONCLUSIONS

Malnutrition is not exclusively an intake defficit and encompasses both the problems derived from a deficit and an excess of nutrients intake. Un to 70% of our patients showed weight excess and a fat mass higher than desirable. The implementation of an individualized nutritional education program, including a vegetables and fiber rich diet, less atherogenic, not only did not cause electrolyte alterations but also slowed the progression of kidney disease.

Processed Plant-Based Foods for CKD Patients: Good Choice, but Be Aware

The beneficial effects of vegetarian diets are known in the general population and in patients with chronic kidney disease (CKD). In recent years, the market has developed a number of processed plant-based products because of several factors (lifestyle changes, ethical concerns, and sustainability). The composition in terms of nutrients, ingredients, and additives of 560 products available on the market and on online shopping sites was analyzed to understand the characteristics of these products. Processed plant-based meat substitutes have a higher content of salt (+467%), lipids (+26%), mostly unsaturated, and fiber with respect to regular animal-based ones. Protein content is lower (−40%) in plant-based products with respect to corresponding animal ones. Of the 49 additives on the label (on average 2 per product), 20 contain phosphorus, sodium, potassium, or nitrogen. Several plant-based processed products may contain elevated amounts of salt and additives, which make them not optimal for CKD patients. Although a plant-based diet remains a very important tool for CKD nutritional management, patients should be aware regarding the extra content of sodium and additives in processed plant-based products compared to animal-based processed food.

Modifiable Lifestyle Behaviors and CKD Progression: A Narrative Review

Living a healthy lifestyle is one of the safest and most cost-effective ways to improve one's quality of life and prevent and/or manage chronic disease. As such, current CKD management guidelines recommend that patients adhere to a healthy diet, perform ≥150 minutes per week of physical activity, manage their body weight, abstain from tobacco use, and limit alcohol. However, there are limited studies that investigate the relationship between these lifestyle factors and the progression of CKD among people with established CKD. In this narrative review, we examine the reported frequencies of health lifestyle behavior engagement among individuals with non-dialysis-dependent CKD and the existing literature that examines the influences of diet, physical activity, weight management, alcohol consumption, and tobacco use on the progression of CKD, as measured by decline in GFR, incident ESKD, or elevated proteinuria or albuminuria in individuals with CKD. Many of the available studies are limited by length of follow-up and small sample sizes, and meta-analyses were limited because the studies were sparse and had heterogeneous classifications of behaviors and/or referent groups and of CKD progression. Further research should be done to determine optimal methods to assess behaviors to better understand the levels at which healthy lifestyle behaviors are needed to slow CKD progression, to investigate the effect of combining multiple lifestyle behaviors on important clinical outcomes in CKD, and to develop effective techniques for behavior change. Despite the lack of evidence of efficacy from large trials on the ability of lifestyle behaviors to slow CKD progression, maintaining a healthy lifestyle remains a cornerstone of CKD management given the undisputed benefits of healthy lifestyle behaviors on cardiovascular health, BP control, and survival.

Alkali therapy protects renal function, suppresses inflammation, and improves cellular metabolism in kidney disease

Chronic kidney disease (CKD) affects about 10-13 % of the population worldwide and halting its progression is a major clinical challenge. Metabolic acidosis is both a consequence and a possible driver of CKD progression. Alkali therapy counteracts these effects in CKD patients, but underlying mechanisms remain incompletely understood. Here we show that bicarbonate supplementation protected renal function in a murine CKD model induced by an oxalate-rich diet. Alkali therapy had no effect on the aldosterone-endothelin axis but promoted levels of the anti-aging protein klotho; moreover, it suppressed adhesion molecules required for immune cell invasion along with reducing T helper cell and inflammatory monocyte invasion. Comparing transcriptomes from the murine crystallopathy model and from human biopsies of kidney transplant recipients suffering from acidosis with or without alkali therapy unveils parallel transcriptome responses mainly associated with lipid metabolism and oxidoreductase activity. Our data reveal novel pathways associated with acidosis in kidney disease and sensitive to alkali therapy and identifies potential targets through which alkali therapy may act on CKD and that may be amenable for more targeted therapies.

KDOQI US Commentary on the KDIGO 2020 Clinical Practice Guideline for Diabetes Management in CKD

In October 2020, KDIGO (Kidney Disease: Improving Global Outcomes) published its first clinical practice guideline directed specifically to the care of patients with diabetes and chronic kidney disease (CKD). This commentary presents the views of the KDOQI (Kidney Disease Outcomes Quality Initiative) work group for diabetes in CKD, convened by the National Kidney Foundation to provide an independent expert perspective on the new guideline. The KDOQI work group believes that the KDIGO guideline takes a major step forward in clarifying glycemic targets and use of specific antihyperglycemic agents in diabetes and CKD. The purpose of this commentary is to carry forward the conversation regarding optimization of care for patients with diabetes and CKD. Recent developments for prevention of CKD progression and cardiovascular events in people with diabetes and CKD, particularly related to sodium/glucose cotransporter 2 (SGLT2) inhibitors, have filled a longstanding gap in nephrology's approach to the care of persons with diabetes and CKD. The multifaceted benefits of SGLT2 inhibitors have facilitated interactions between nephrology, cardiology, endocrinology, and primary care, underscoring the need for innovative approaches to multidisciplinary care in these patients. We now have more interventions to slow kidney disease progression and prevent or delay kidney failure in patients with diabetes and kidney disease, but methods to streamline their implementation and overcome barriers in access to care, particularly cost, are essential to ensuring all patients may benefit.

Plant-Based Diets and Peritoneal Dialysis: A Review

Whole food plant-based diets are gaining popularity as a preventative and therapeutic modality for numerous chronic health conditions, including chronic kidney disease, but their role and safety in end-stage kidney disease patients on peritoneal dialysis (PD) is unclear. Given the general public's increased interest in this dietary pattern, it is likely that clinicians will encounter individuals on PD who are either consuming, considering, or interested in learning more about a diet with more plants. This review explores how increasing plant consumption might affect those on PD, encompassing potential benefits, including some specific to the PD population, and potential concerns.

Lower bicarbonate level is associated with CKD progression and all-cause mortality: a propensity score matching analysis

Background

Although metabolic acidosis is known as a potential complication of chronic kidney disease (CKD), there is limited information concerning the association between metabolic acidosis and clinical outcomes.

Methods

Five hundred fifty-two patients referred to renal division of Iwata City Hospital from 2015 to 2017 were included as a retrospective CKD cohort, and finally 178 patients with CKD stage III or IV and 20 to 80 years of age were analyzed. We examined the association between serum bicarbonate (HCO₃⁻) levels and clinical outcomes using Kaplan-Meier methods after the matching of baseline characteristics by propensity scores.

Results

Of 178 patients with CKD, patients with lower HCO₃⁻ levels (N = 94), as compared with patients with higher HCO₃⁻ levels (N = 84), were more likely to be male (P < 0.05), had more severe CKD stages (P < 0.05), more frequent use of renin-angiotensin system inhibitor (P < 0.05) or uric acid lowering agent (P < 0.001), heavier body weight (P < 0.001) and lower estimated glomerular filtration rate (P < 0.05). In Kaplan-Meier analysis after propensity score matching, the incidence of composite outcome as the doubling of serum creatinine level from baseline, end-stage kidney disease requiring the initiation of dialysis, or death from any causes was significantly fewer in the higher HCO₃⁻ group than the lower HCO₃⁻ group (N = 57 each group, P = 0.016).

Conclusions

Lower HCO₃⁻ level is significantly associated with the doubling of serum creatinine level, end-stage kidney disease or all-cause mortality in patients with CKD.

Trial registration

This study was registered with the Clinical Trial Registry of the University Hospital Medical Information Network (http://www.umin.ac.jp/, study number: UMIN000044861).

Effects of veverimer on serum bicarbonate and physical function in women with chronic kidney disease and metabolic acidosis: a subgroup analysis from a randomised, controlled trial

BACKGROUND

Globally, the prevalence of chronic kidney disease (CKD) is higher in women than in men; however, women have been historically under-represented in nephrology clinical trials. Metabolic acidosis increases risk of progressive loss of kidney function, causes bone demineralization and muscle protein catabolism, and may be more consequential in women given their lower bone and muscle mass. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis.

METHODS

This was a Phase 3, multicenter, randomised, blinded, placebo-controlled trial in 196 patients with CKD (eGFR: 20-40 mL/min/1.73 m2) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo. We present the findings from a pre-specified subgroup analysis evaluating the effects of veverimer on metabolic acidosis and physical function among women (N = 77) enrolled in this trial.

RESULTS

At week 52, women treated with veverimer had a greater increase in mean (± standard error) serum bicarbonate than the placebo group (5.4 [0.5] vs. 2.2 [0.6] mmol/L; P < 0.0001). Physical Function reported by patients on the Kidney Disease and Quality of Life - Physical Function Domain, a measure that includes items related to walking, stair climbing, carrying groceries and other activities improved significantly in women randomized to veverimer vs placebo (+ 13.2 vs. -5.2, respectively, P < 0.0031). Objectively measured performance time on the repeated chair stand test also improved significantly in the veverimer group vs. placebo (P = 0.0002).

CONCLUSIONS

Veverimer was effective in treating metabolic acidosis in women with CKD, and significantly improved how they felt and functioned.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03390842 . Registered on January 4, 2018.

Effects of oral alkali drug therapy on clinical outcomes in pre-dialysis chronic kidney disease patients: a systematic review and meta-analysis

BACKGROUND

Metabolic acidosis accelerates the progression of chronic kidney disease (CKD) and increases the mortality rate. Whether oral alkali drug therapy benefits pre-dialysis CKD patients is controversial. We performed a meta-analysis of the effects of oral alkali drug therapy on major clinical outcomes in pre-dialysis CKD patients.

METHODS

We systematically searched MEDLINE using the Ovid, EMBASE, and Cochrane Library databases without language restriction. We included all eligible clinical studies that involved pre-dialysis CKD adults and compared those who received oral alkali drug therapy with controls.

RESULTS

A total of 18 eligible studies, including 14 randomized controlled trials and 4 cohort studies reported in 19 publications with 3695 participants, were included. Oral alkali drug therapy led to a 55% reduction in renal failure events (relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.25-0.82), a rate of decline in the estimated glomerular filtration rate (eGFR) of 2.59 mL/min/1.73 m² per year (95% CI, 0.88-4.31). There was no significant effect on decline in eGFR events (RR: 0.34; 95% CI: 0.09-1.23), proteinuria (standardized mean difference: -0.32; 95% CI: -1.08 to 0.43), all-cause mortality events (RR: 0.90; 95% CI: 0.40-2.02) and cardiovascular (CV) events (RR: 1.03; 95% CI: 0.32-3.37) compared with the control groups.

CONCLUSION

Based on the available and low-to-moderate certainty evidence, oral alkali drug therapy might potentially reduce the risk of kidney failure events, but no benefit in reducing all-cause mortality events, CV events, decline in eGFR and porteninuria.

Association of urinary angiotensinogen with renal arteriolar remodeling in chronic kidney disease

OBJECTIVE

Renin-angiotensin system (RAS) might be associated with arteriolar remodeling. The present study aimed to explore the hitherto unknown relationship between renal RAS and renal arteriolar remodeling and to elucidate whether altered renal RAS subsequently affects renal function in patients with chronic kidney disease (CKD).

METHODS

In this retrospective study, patients with various CKDs not using RAS inhibitors who underwent renal biopsy were included in cross-sectional and longitudinal analyses. Urinary angiotensinogen (UAGT) levels and wall/lumen ratio (WLR) were determined to evaluate renal RAS and renal arteriolar remodeling, respectively. The association between ln(UAGT) and ln(WLR) was cross-sectionally examined using a liner regression model. Furthermore, the association of ln(UAGT) with subsequent changes in estimated glomerular filtration rate (eGFR) per year were longitudinally examined in the largest subgroup of patients who were diagnosed with IgA nephropathy.

RESULTS

In the overall cohort (n = 54), the median age, blood pressures, eGFR, and WLR were 37 years, 120/73 mmHg, 85 ml/min per 1.73 m2, and 0.93, respectively. Ln(UAGT) was significantly and positively associated with ln(WLR) even after adjusting for classical and nonclassical clinical renal risk factors. In patients with IgA nephropathy, higher ln(UAGT) was associated with higher ln(WLR). Ln(UAGT) also tended to be associated with a greater decline in eGFR per year over a median period of 8.7 years, even after adjusting for potential confounding factors.

CONCLUSION

In patients with CKD, renal RAS might be associated with renal arteriolar remodeling and future decline in eGFR, independent of potential risk factors.

Effects of Dietary App-Supported Tele-Counseling on Sodium Intake, Diet Quality, and Blood Pressure in Patients With Diabetes and Kidney Disease

OBJECTIVES

The aim of this study is to examine the effect of a telehealth intervention that used a dietary app, educational website, and weekly dietitian tele-counseling on sodium intake, diet quality, blood pressure, and albuminuria among individuals with diabetes and early-stage chronic kidney disease.

DESIGN AND METHODS

We examined the effects of a dietary app-supported tele-counseling intervention in a single center, single arm study of 44 participants with type 2 diabetes and stage 1-3a chronic kidney disease. Participants recorded and shared dietary data via MyFitnessPal with registered dietitians, who used motivational interviewing to provide telephone counseling weekly for 8 weeks. After the 8-week intensive intervention, participants were followed at 6 and 12 months. Outcomes included 24-hour urine sodium (2 collections per timepoint), Healthy Eating Index 2015 score (three 24-hour dietary recalls per timepoint), 24-hour systolic blood pressure (SBP) and diastolic blood pressure (DBP), and 24-hour urine albumin excretion.

RESULTS

Out of 44 consented participants (mean age 60.3 ± 11.9 years, 43% female, 89% white, median estimated glomerular filtration rate was 78.5 mL/min/1.73 m², median urine albumin excretion 52.9 mg/day, 84% hypertension), 32 (73%) completed 8-week follow-up, 27 (61%) completed 6-month follow-up, and 25 (57%) completed 12-month follow-up. Among participants who completed 12-month follow-up, reported sodium intake decreased by 638 mg/day from baseline of 2,919 mg/day (P < .001). The 24-hour mean urine sodium and albumin excretion did not decline over the study period. Healthy Eating Index 2015 score improved by 7.76 points at 12 months from a mean baseline of 54.6 (P < .001). Both 24-hour SBP and DBP declined at 12 months from baseline (SBP -5.7 mm Hg, 95% confidence interval -10.5 to -1.0, P = .02; DBP -4.1 mm Hg, 95% confidence interval -7.2 to -1.1, P = .01).

CONCLUSIONS

Overall, this study demonstrates that a short, intensive, remotely delivered dietary intervention for adults with type 2 diabetes and early chronic kidney disease at high risk for disease progression and cardiovascular complications led to improvement in blood pressure and self-reported sodium intake and diet quality, but no improvement in albuminuria. Future research studies are needed to examine whether remotely delivered dietary interventions can ultimately improve kidney health over time.

Dietary Acid Load and Relationship with Albuminuria and Glomerular Filtration Rate in Individuals with Chronic Kidney Disease at Predialysis State

The Western diet, characterized by excessive consumption of animal protein and reduced intake of vegetables and fruits, is also rich in sulfur, chlorine, and organic acids, which are the main sources of dietary acid load. A relationship between dietary acid load, renal function, and progression of chronic kidney disease has been demonstrated. Dietary modifications seem to contribute to a reduction in dietary acid load, and are associated with improved outcomes in individuals with chronic kidney disease (CKD). The aim of this paper was to review the existing evidence concerning the association between dietary acid load and renal function in nondialyzed individuals with CKD. A systematic review was conducted by gathering articles in electronic databases (MEDLINE/PubMed, Scopus, and Web of Science) from January 2018 to May 2021. Dietary acid load and GFR and/or albuminuria were analyzed. A total of 1078 articles were extracted, of which 5 met the inclusion criteria. Only one study found no statistically significant associations between the study variables. The remaining showed a negative association between dietary acid load and renal function. This systematic review confirmed the existence of an association between dietary acid load and renal function, with a high dietary acid load contributing to a decreased renal function.

2021 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association

Poor diet quality is strongly associated with elevated risk of cardiovascular disease morbidity and mortality. This scientific statement emphasizes the importance of dietary patterns beyond individual foods or nutrients, underscores the critical role of nutrition early in life, presents elements of heart-healthy dietary patterns, and highlights structural challenges that impede adherence to heart-healthy dietary patterns. Evidence-based dietary pattern guidance to promote cardiometabolic health includes the following: (1) adjust energy intake and expenditure to achieve and maintain a healthy body weight; (2) eat plenty and a variety of fruits and vegetables; (3) choose whole grain foods and products; (4) choose healthy sources of protein (mostly plants; regular intake of fish and seafood; low-fat or fat-free dairy products; and if meat or poultry is desired, choose lean cuts and unprocessed forms); (5) use liquid plant oils rather than tropical oils and partially hydrogenated fats; (6) choose minimally processed foods instead of ultra-processed foods; (7) minimize the intake of beverages and foods with added sugars; (8) choose and prepare foods with little or no salt; (9) if you do not drink alcohol, do not start; if you choose to drink alcohol, limit intake; and (10) adhere to this guidance regardless of where food is prepared or consumed. Challenges that impede adherence to heart-healthy dietary patterns include targeted marketing of unhealthy foods, neighborhood segregation, food and nutrition insecurity, and structural racism. Creating an environment that facilitates, rather than impedes, adherence to heart-healthy dietary patterns among all individuals is a public health imperative.

Metabolic Acidosis in Chronic Kidney Disease: Pathogenesis, Clinical Consequences, and Treatment

The kidneys play an important role in regulating the acid-base balance. Metabolic acidosis is common in chronic kidney disease (CKD) patients and can lead to poor outcomes, such as bone demineralization, muscle mass loss, and worsening of renal function. Metabolic acidosis is usually approached with evaluating the serum bicarbonate levels but should be assessed by counting blood pH. Current guidelines recommend oral bicarbonate supplementation to maintain the serum bicarbonate levels within the normal range. However, a slow decline in the glomerular filtration rate might occur, even though the serum bicarbonate levels were in the normal range. Because the serum bicarbonate levels decrease when metabolic acidosis advances, other biomarkers are necessary to indicate acid retention for early diagnosis of metabolic acidosis. For this, urine citrate and ammonium excretion may be used to follow the course of CKD patients. Metabolic acidosis can be treated with an increased fruit and vegetable intake and oral alkali supplementation. Previous studies have suggested that administration of oral sodium bicarbonate may preserve kidney function without significant increases in blood pressure and body weight. Veverimer, a non-absorbed, counterion-free, polymeric drug, is emerging to treat metabolic acidosis, but further researches are awaited. Further studies are also needed to clarify the target therapeutic range of serum bicarbonate and the drugs used for metabolic acidosis.

Association of serum bicarbonate with graft survival and mortality in kidney transplant recipients

BACKGROUND

Metabolic acidosis is an independent risk factor for kidney disease progression with a high prevalence after kidney transplantation (KTx). Remarkably, it is still unclear if there is an impact of metabolic acidosis on graft function and death after KTx. Thus, we wanted to investigate if serum bicarbonate is associated with long-term graft outcome and mortality after KTx.

METHODS

We performed a single-center retrospective study including adult de novo KTx patients between 1999 and 2015. Cox proportional hazard model was used to analyze a possible association between time-dependent serum bicarbonate measurements and graft failure or death.

RESULTS

Four hundred thirty KTRs were included in the analysis with a mean age of 50.9 ± 13.4 years. Mean observation time was 4.7 ± 2.8 years. Two hundred eighty-four (66%) patients were male and 318 (74%) had received a deceased donor kidney transplant. Mean bicarbonate and eGFR levels 1 year post-transplant amounted to 22.9 ± 3.1 mEq/L and 61 ± 26 ml/min/1.73 m², respectively. Prevalence of metabolic acidosis was 31% 1 year after transplantation. Fourteen (3%) patients died and 31 (7%) suffered from graft failure. Higher bicarbonate levels were associated with significantly lower hazards for graft failure (Hazard Ratio (HR) = 0.88; 95% Confidence Interval (CI): 0.79-0.98) and mortality (HR = 0.79; 95% CI 0.66-0.93) after adjusting for potential confounders such as age, donor type and time-varying eGFR.

CONCLUSIONS

Our analysis showed that higher serum bicarbonate levels are positively associated with long-term graft and patient survival in kidney transplant recipients. Thus, serum bicarbonate may serve as a predictor and independent risk factor for graft and patient outcome after KTx as has been previously shown for patients with CKD.

Obesity, Anion Accumulation, and Anion Gap Metabolic Acidosis: A Cohort Study

Background

Obesity is associated with low serum bicarbonate, an indicator of metabolic acidosis and a CKD risk factor. To further characterize acid-base disturbance and subclinical metabolic acidosis in this population, we examined prospective associations of body mass index (BMI) with elevated anion gap and whether anion gap values in obesity associate with low bicarbonate.

Methods

Data from adult outpatients (n=94,448) in the Bronx, New York were collected from 2010 to 2018. Mixed effects models and Cox proportional hazards models were used to examine associations of BMI with elevated anion gap and anion gap metabolic acidosis and of baseline anion gap with incident low bicarbonate and anion gap metabolic acidosis. Anion gap was defined using traditional and albumin-corrected calculations.

Results

Greater BMI was associated with higher anion gap over time and with progressively greater risk of developing an elevated anion gap (hazard ratio [HR] for body mass index [BMI]≥40 kg/m2 versus 18 to <25 kg/m2, 1.32; 95% confidence interval [95% CI], 1.23 to 1.42 for traditional and HR for BMI≥40 kg/m2 versus 18 to <25 kg/m2, 1.74; 95% CI, 1.63 to 1.85 for corrected). Higher BMI was also associated with increased risk of developing anion gap metabolic acidosis (HR for BMI≥40 kg/m2, 1.53; 95% CI, 1.39 to 1.69). Among patients with obesity, higher anion gap was associated with increased risk of incident low bicarbonate (HR for fourth versus first quartile, 1.29; 95% CI, 1.23 to 1.44 for traditional and HR for fourth versus first quartile, 1.36; 95% CI, 1.26 to 1.48 for corrected) and higher risk of anion gap metabolic acidosis (HR for fourth versus first quartile, 1.78; 95% CI, 1.59 to 1.99).

Conclusions

Obesity is characterized by unmeasured anion accumulation and acid retention or overproduction. Modest elevations in anion gap among patients with obesity are associated with previously unrecognized anion gap metabolic acidosis.

Plant-based Diets in Kidney Disease: Nephrology Professionals' Perspective

OBJECTIVE

Plant-based diets can delay the progression of chronic kidney disease (CKD) and help manage complications and co-morbid conditions such as hypertension, acidosis, diabetes, and cardiovascular disease. However, it is unclear how often plant-based diets are recommended to patients with kidney disease. The objective of this study was to understand nephrology professionals' familiarity, perception, and recommendation of plant-based diets to people with kidney disease.

DESIGN AND METHODS

A survey to understand perception of recommendation of plant-based diets for patients with CKD was developed. Nephrology professionals from the National Kidney Foundation's member directory were e-mailed a link to complete the survey online. This directory includes professionals who work in a variety of nephrology settings, including both CKD and end-stage renal disease care. Survey items were evaluated with descriptive statistics. Differences across items were determined using chi-square tests and t-tests.

RESULTS

A total of 3,901 professionals were sent the survey, and 644 completed the survey. A majority were dietitians (58%) and worked in dialysis clinics (54%). Most (88%) had heard of using plant-based diets for kidney disease treatment, and a majority (88%) believed it could improve CKD management, cardiovascular disease (90%), hypertension (90%), diabetes (84%), high cholesterol (90%), and obesity (84%). Dietitians were more likely to report plant-based diets as beneficial for each health condition (P < .05). Professionals were most confident that a plant-based diet could help control hypertension (3.75 ± 0.99 on a scale of 1-5), compared with delaying progression of CKD (3.68 ± 1.15) or treating acidosis (3.68 ± 1.13). Dietitians felt more confident in their ability to plan a balanced plant-based diet compared with other specialties (3.49 vs. 2.74, P < .001).

CONCLUSION

Nephrology professionals who work in nondialysis-dependent CKD settings, and those who work with patients on dialysis, are aware of the benefits of plant-based diets in kidney disease. However, plant-based diets are not routinely being offered as a treatment option. Nephrology practices should work to increase dietitian referrals to offer patients support in transitioning to a plant-based diet.

Metabolic Acidosis and Cardiovascular Disease in CKD

Rationale & Objective

Metabolic acidosis related to chronic kidney disease (CKD) is associated with an accelerated decline in glomerular filtration rate (GFR) and the development of end-stage kidney disease. Whether metabolic acidosis is associated with cardiovascular (CV) events in patients with CKD is unclear.

Study Design

Retrospective cohort study.

Setting & Participants

The Optum De-identified Electronic Health Records Dataset, 2007–2017, was used to generate a cohort of patients with non-dialysis-dependent CKD who had at least 3 estimated GFR < 60 mL/min/1.73 m². Patients with metabolic acidosis (serum bicarbonate 12 to <22 mEq/L) or normal serum bicarbonate (22‒29 mEq/L) at baseline were identified by 2 consecutive measurements 28‒365 days apart.

Predictor

Serum bicarbonate as a continuous variable.

Outcome

Primary outcome was a composite of major adverse cardiovascular events (MACE+). Secondary outcomes included individual components of the composite outcome.

Analytical Approach

Cox proportional hazards models to evaluate the association between 1-mEq/L increments in serum bicarbonate and MACE+.

Results

A total of 51,558 patients were evaluated, 34% had metabolic acidosis. The median follow-up period was 3.9–4.5 years, depending on the outcome assessed. The adjusted hazard ratio (HR) for MACE+ was 0.964 (95% CI, 0.961–0.968). For the individual components of incident heart failure (HF), stroke, myocardial infarction (MI), and CV death, HRs were 0.98 (95% CI, 0.97–0.98), 0.98 (95% CI, 0.97–0.99), 0.96 (95% CI, 0.96–0.97), and 0.94 (95% CI, 0.93–0.94), respectively, for every 1-mEq/L increase in serum bicarbonate.

Limitations

Possible residual confounding.

Conclusions

Metabolic acidosis in CKD is associated with an increased risk of MACE+ as well as the individual components of incident HF, stroke, MI, and CV death. Randomized controlled trials evaluating treatments for the correction of metabolic acidosis in CKD to prevent CV events are needed.

Metabolic Acidosis in Patients with CKD: Epidemiology, Pathogenesis, and Treatment

BACKGROUND

Metabolic acidosis in CKD is diagnosed in patients with plasma or venous blood bicarbonate concentration lower than 22 mmol/L. Metabolic acidosis occurs in about 20% of patients with CKD. Metabolic acidosis may lead to dysfunction of many systems and organs as well as CKD progression. Currently, sodium bicarbonate is mainly used for pharmacological treatment of metabolic acidosis in patients with CKD. Veverimer is a new drug dedicated to treatment of metabolic acidosis in patients with CKD. Orally given veverimer binds hydrogen ions in the intestines and subsequently is excreted from the body with feces. Clinical studies have shown that veverimer is effective in increasing serum bicarbonate concentrations in CKD patients with metabolic acidosis. Here, we present review of the epidemiology, pathogenesis, diagnosis, treatment, and prevention of metabolic acidosis in CKD patients.

SUMMARY

Metabolic acidosis is common in patients with CKD and contributes to CKD progression and many complications, which worsen the prognosis in these patients. Currently, sodium bicarbonate is mainly used in metabolic acidosis treatment. The role of the new drug veverimer in the metabolic acidosis therapy needs further studies.

KEY MESSAGE

The aim of this review article is to summarize the current knowledge concerning the epidemiology, pathogenesis, diagnosis, treatment, and prevention of metabolic acidosis in CKD patients.

Lifestyle interventions for preventing and ameliorating CKD in primary and secondary care

PURPOSE OF REVIEW

Despite the growth in chronic kidney disease (CKD) epidemics, evidence-based lifestyle recommendations for primary prevention of CKD are limited by reliance on observational studies and predominantly pilot clinical trials.

RECENT FINDINGS

Emerging data have shown lifestyle modification strategies for primary CKD prevention with the most evidence favoring a healthy dietary pattern (rich in fruit, vegetables, potassium and have a higher plant-based to animal protein ratio), and diet low in sodium, being physically active, avoiding tobacco smoking, moderating alcohol consumption and maintaining a healthy body weight. The way these behavioral interventions can be implemented in practice should consider their synergistic benefit as well as mechanisms to facilitate long-term behavior change. Sustaining long-term behavior change remains a challenge in practice, particularly due to a lack of healthcare resources and behavior relapse. Some suggestions to mitigate this include ensuring adequate time is spent in intervention codesign and planning, utilizing adaptive trial/intervention designs with regular intervention tailoring for intervention dose, intensity, duration, and modality.

SUMMARY

A number of modifiable lifestyle behaviors consistently associate with developing CKD in the community. The current evidence base, despite its inherent limitations, may inform both public health recommendations and clinical practice.