Effects of oral sodium bicarbonate in patients with CKD

Metabolic Acidosis in CKD: Pathogenesis, Adverse Effects, and Treatment Effects

Metabolic acidosis is a frequent complication of chronic kidney disease and is associated with a number of adverse outcomes, including worsening kidney function, poor musculoskeletal health, cardiovascular events, and death. Mechanisms that prevent metabolic acidosis detrimentally promote further kidney damage, creating a cycle between acid accumulation and acid-mediated kidney injury. Disrupting this cycle through the provision of alkali, most commonly using sodium bicarbonate, is hypothesized to preserve kidney function while also mitigating adverse effects of excess acid on bone and muscle. However, results from clinical trials have been conflicting. There is also significant interest to determine whether sodium bicarbonate might improve patient outcomes for those who do not have overt metabolic acidosis. Such individuals are hypothesized to be experiencing acid-mediated organ damage despite having a normal serum bicarbonate concentration, a state often referred to as subclinical metabolic acidosis. Results from small- to medium-sized trials in individuals with subclinical metabolic acidosis have also been inconclusive. Well-powered clinical trials to determine the efficacy and safety of sodium bicarbonate are necessary to determine if this intervention improves patient outcomes.

Skeletal Muscle Injury in Chronic Kidney Disease-From Histologic Changes to Molecular Mechanisms and to Novel Therapies

Chronic kidney disease (CKD) is associated with significant reductions in lean body mass and in the mass of various tissues, including skeletal muscle, which causes fatigue and contributes to high mortality rates. In CKD, the cellular protein turnover is imbalanced, with protein degradation outweighing protein synthesis, leading to a loss of protein and cell mass, which impairs tissue function. As CKD itself, skeletal muscle wasting, or sarcopenia, can have various origins and causes, and both CKD and sarcopenia share common risk factors, such as diabetes, obesity, and age. While these pathologies together with reduced physical performance and malnutrition contribute to muscle loss, they cannot explain all features of CKD-associated sarcopenia. Metabolic acidosis, systemic inflammation, insulin resistance and the accumulation of uremic toxins have been identified as additional factors that occur in CKD and that can contribute to sarcopenia. Here, we discuss the elevation of systemic phosphate levels, also called hyperphosphatemia, and the imbalance in the endocrine regulators of phosphate metabolism as another CKD-associated pathology that can directly and indirectly harm skeletal muscle tissue. To identify causes, affected cell types, and the mechanisms of sarcopenia and thereby novel targets for therapeutic interventions, it is important to first characterize the precise pathologic changes on molecular, cellular, and histologic levels, and to do so in CKD patients as well as in animal models of CKD, which we describe here in detail. We also discuss the currently known pathomechanisms and therapeutic approaches of CKD-associated sarcopenia, as well as the effects of hyperphosphatemia and the novel drug targets it could provide to protect skeletal muscle in CKD.

Pathophysiology of Diet-Induced Acid Stress

Diets can influence the body's acid-base status because specific food components yield acids, bases, or neither when metabolized. Animal-sourced foods yield acids and plant-sourced food, particularly fruits and vegetables, generally yield bases when metabolized. Modern diets proportionately contain more animal-sourced than plant-sourced foods, are, thereby, generally net acid-producing, and so constitute an ongoing acid challenge. Acid accumulation severe enough to reduce serum bicarbonate concentration, i.e., manifesting as chronic metabolic acidosis, the most extreme end of the continuum of "acid stress", harms bones and muscles and appears to enhance the progression of chronic kidney disease (CKD). Progressive acid accumulation that does not achieve the threshold amount necessary to cause chronic metabolic acidosis also appears to have deleterious effects. Specifically, identifiable acid retention without reduced serum bicarbonate concentration, which, in this review, we will call "covert acidosis", appears to cause kidney injury and exacerbate CKD progression. Furthermore, the chronic engagement of mechanisms to mitigate the ongoing acid challenge of modern diets also appears to threaten health, including kidney health. This review describes the full continuum of "acid stress" to which modern diets contribute and the mechanisms by which acid stress challenges health. Ongoing research will develop clinically useful tools to identify stages of acid stress earlier than metabolic acidosis and determine if dietary acid reduction lowers or eliminates the threats to health that these diets appear to cause.

In the "Plant-Based" Era, Patients With Chronic Kidney Disease Should Focus on Eating Healthy

In the era of plant-based diets, it is important for Nephrology providers to know the evidence regarding their healthfulness in patients with chronic kidney disease (CKD). A whole food, plant-based diet, which emphasizes fresh, minimally processed or refined plant-based foods and limits animal products, has shown benefits for patients with CKD. These include reduced dietary acid load, lower bioavailability of potassium and phosphorus, increased dietary fiber intake, nutritional adequacy, and cardiovascular and mortality benefits. Potential drawbacks include the need for specific knowledge, skills, and cost involved in preparing varied, healthy, and appetizing plant-based meals, leading to lower acceptability and accessibility to certain populations. Liberalization of the standard CKD diet to include healthy, minimally processed foods such as fruits, vegetables, nuts, legumes, and whole grains is likely beneficial, though more research is needed to determine whether a plant-based-only diet is the optimal way to achieve healthier eating in patients with CKD.

Effects of correcting metabolic acidosis on muscle mass and functionality in chronic kidney disease: a systematic review and meta-analysis

Metabolic acidosis unfavourably influences the nutritional status of patients with non-dialysis dependent chronic kidney disease (CKD) including the loss of muscle mass and functionality, but the benefits of correction are uncertain. We investigated the effects of correcting metabolic acidosis on nutritional status in patients with CKD in a systematic review and meta-analysis. A search was conducted in MEDLINE and the Cochrane Library from inception to June 2023. Study selection, bias assessment, and data extraction were independently performed by two reviewers. The Cochrane risk of bias tool was used to assess the quality of individual studies. We applied random effects meta-analysis to obtain pooled standardized mean difference (SMD) and 95% confidence intervals (CIs). We retrieved data from 12 intervention studies including 1995 patients, with a mean age of 63.7 ± 11.7 years, a mean estimated glomerular filtration rate of 29.8 ± 8.8 mL/min per 1.73 m2 , and 58% were male. Eleven studies performed an intervention with oral sodium bicarbonate compared with either placebo or with standard care and one study compared veverimer, an oral HCl-binding polymer, with placebo. The mean change in serum bicarbonate was +3.6 mEq/L in the intervention group and +0.4 mEq/L in the control group. Correcting metabolic acidosis significantly improved muscle mass assessed by mid-arm muscle circumference (SMD 0.35 [95% CI 0.16 to 0.54], P < 0.001) and functionality assessed with the sit-to-stand test (SMD -0.31 [95% CI -0.52 to 0.11], P = 0.003). We found no statistically significant effects on dietary protein intake, handgrip strength, serum albumin and prealbumin concentrations, and blood urea nitrogen. Correcting metabolic acidosis in patients with CKD improves muscle mass and physical function. Correction of metabolic acidosis should be considered as part of the nutritional care for patients with CKD.

The effects of oral sodium bicarbonate supplementation on anthropometric measures in patients with chronic kidney disease: A systematic review and meta-analysis of randomized clinical trials

Metabolic acidosis (MA) may play a key role in the pathogenesis of protein-energy wasting (PEW) in patients with chronic kidney disease (CKD). To present a comprehensive synthesis of the effect of oral sodium bicarbonate (SB) supplementation on anthropometric measures in patients with CKD, a systematic review was undertaken in PubMed/MEDLINE, Web of Science, Cochrane CENTRAL, and Google Scholar, of relevant articles published prior to September 2022. The summary statistics of effect size, nonstandardized weighted mean difference (WMD), and 95% confidence interval (CI) were used to compare the effects of SB supplementation on anthropometric parameters vs. control group. To detect probable sources of heterogeneity, a series of predefined subgroup analyses were conducted. In total, 17 studies with 21 treatment arms, including 2203 participants (1149 cases, 1054 controls), met our inclusion criteria and were included in the meta-analysis. SB supplementation had no significant effect on body weight (BW), midarm muscle circumference (MAMC), or lean body mass (LBM) in patients with CKD. There was a significant increase in body mass index (BMI) (MD: 0.59 kg/m2, 95% CI: 0.25 to 0.93, p = 0.001) after SB supplementation in the overall analysis. In subgroup analysis, LBM was increased in studies that were ≥ 24-week duration (MD: 1.81 kg, 95% CI: 0.81 to 2.81) and in participants with BMI lower than 27 kg/m2 (MD: 1.81 mg/L, 95% CI: 0.81 to 2.81). SB supplementation may yield increases in BMI in predialysis CKD patients. However, our findings did not support the beneficial effects of SB supplementation on other anthropometric outcomes. There is an evident need for long-term high-quality interventions to confirm these findings.

Sodium Bicarbonate Treatment and Vascular Function in CKD: A Randomized, Double-Blind, Placebo-Controlled Trial

SIGNIFICANCE STATEMENT

Lower serum bicarbonate levels, even within the normal range, are strongly linked to risks of cardiovascular disease in CKD, possibly by modifying vascular function. In this randomized, controlled trial, treatment with sodium bicarbonate (NaHCO 3 ) did not improve vascular endothelial function or reduce arterial stiffness in participants with CKD stage 3b-4 with normal serum bicarbonate levels. In addition, NaHCO 3 treatment did not reduce left ventricular mass index. NaHCO 3 did increase plasma bicarbonate levels and urinary citrate excretion and reduce urinary ammonium excretion, indicating that the intervention was indeed effective. NaHCO 3 therapy was safe with no significant changes in BP, weight, or edema. These results do not support the use of NaHCO 3 for vascular dysfunction in participants with CKD.

BACKGROUND

Lower serum bicarbonate levels, even within the normal range, are strongly linked to risks of cardiovascular disease in CKD, possibly by modifying vascular function. Prospective interventional trials with sodium bicarbonate (NaHCO 3 ) are lacking.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial examining the effect of NaHCO 3 on vascular function in 109 patients with CKD stage 3b-4 (eGFR 15-44 ml/min per 1.73 m 2 ) with normal serum bicarbonate levels (22-27 mEq/L). Participants were randomized 1:1 to NaHCO 3 or placebo at a dose of 0.5 mEq/lean body weight-kg per day for 12 months. The coprimary end points were change in brachial artery flow-mediated dilation (FMD) and change in aortic pulse wave velocity over 12 months.

RESULTS

Ninety patients completed this study. After 12 months, plasma bicarbonate levels increased significantly in the NaHCO 3 group compared with placebo (mean [SD] difference between groups 1.35±2.1, P = 0.003). NaHCO 3 treatment did not result in a significant improvement in aortic pulse wave velocity from baseline. NaHCO 3 did result in a significant increase in flow-mediated dilation after 1 month; however, this effect disappeared at 6 and 12 months. NaHCO 3 resulted in a significant increase in 24-hour urine citrate and pH and a significant decrease in 24-hour urine ammonia. There was no significant change in left ventricular mass index, ejection fraction, or eGFR with NaHCO 3 . NaHCO 3 treatment was safe and well-tolerated with no significant changes in BP, antihypertensive medication, weight, plasma calcium, or potassium levels.

CONCLUSION

Our results do not support the use of NaHCO 3 for vascular dysfunction in participants with CKD and normal serum bicarbonate levels.

Clinical features and molecular mechanism of muscle wasting in end stage renal disease

Muscle wasting in end-stage renal disease (ESRD) is an escalating issue due to the increasing global prevalence of ESRD and its significant clinical impact, including a close association with elevated mortality risk. The phenomenon of muscle wasting in ESRD, which exceeds the rate of muscle loss observed in the normal aging process, arises from multifactorial processes. This review paper aims to provide a comprehensive understanding of muscle wasting in ESRD, covering its epidemiology, underlying molecular mechanisms, and current and emerging therapeutic interventions. It delves into the assessment techniques for muscle mass and function, before exploring the intricate metabolic and molecular pathways that lead to muscle atrophy in ESRD patients. We further discuss various strategies to mitigate muscle wasting, including nutritional, pharmacological, exercise, and physical modalities intervention. This review seeks to provide a solid foundation for future research in this area, fostering a deeper understanding of muscle wasting in ESRD, and paving the way for the development of novel strategies to improve patient outcomes. [BMB Reports 2023; 56(8): 426-438].

Effects of Oral Sodium Bicarbonate Supplementation on Protein Metabolism and Inflammation in Iraqi Hemodialysis Patients: An Open-Label Randomized Controlled Trial

Background

The effect of correcting metabolic acidosis on protein metabolism in hemodialysis patients is controversial.

Objectives

To study the effects of oral sodium bicarbonate on protein metabolism and markers of inflammation in acidotic hemodialysis patients. Patients and Methods. An open-label randomized controlled trial was conducted at a single center. Sixty-six clinically stable adult hemodialysis patients were recruited with an average predialysis serum bicarbonate level of <22 mmol/l and a dialysate bicarbonate concentration of 35 mmol/l. Forty-nine participants have completed the study. Oral sodium bicarbonate tablets of 500 mg were given daily in the intervention group (n = 25) for 12 weeks versus the standard of care in the control group (n = 24). Outcomes compared intervention versus nonintervention in both groups at equivalent time points (0 and 3 months). The clinical data, anthropometry, dialysis adequacy, albumin, normalized protein catabolism rate, blood gas analysis, and bicarbonate were recorded at 0 and 3 months. In addition, muscle mass and handgrip strength were measured. Finally, IL-6 as a marker of inflammation was measured at randomization and three months.

Results

Serum bicarbonate and pH increased significantly from 17.57 ± 3.34 mmol/L to 20.69 ± 2.54 mmol/L and from 7.26 ± 0.06 to 7.34 ± 0.04, respectively (p < 0.0001). Serum albumin was significantly higher in the intervention group at three months than in the control group, 4.11 ± 0.45 vs. 3.79 ± 0.47 (p value 0.011). Serum potassium significantly decreased in the intervention group at three months compared to the control group, 5.00 ± 0.43 mEq/l vs. 5.33 ± 0.63 mEq/l (p value 0.03). Muscle strength expressed as handgrip has improved significantly in the intervention group at three months compared to the control group, 45.01 ± 19.19 vs. 33.93 ± 15.06 (p value 0.03). The IL-6 values were less in the intervention group at 3 months with a p value of 0.01. The interdialytic weight of the intervention group at three months was 2.42 ± 0.64 compared to the 2.20 ± 1.14 control group, but this did not reach statistical significance (p value of 0.4). The composite of (albumin + nPCR) at three months was achieved in 59.18% of the intervention group compared to 14.28% with a p value of 0.01.

Conclusions

Correcting metabolic acidosis in hemodialysis patients improved serum albumin and nPCR without hypokalemia or significant interdialytic weight gain. This was particularly evident in patients with minimal inflammation with low IL-6 values.

Neurocirculatory regulation and adaptations to exercise in chronic kidney disease

Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors may be improved through exercise training, with a specific focus on the sympathetic nervous system. Important areas for future work include understanding how the exercise prescription may best be optimized in CKD and how the beneficial effects of exercise training may extend to the brain.

Effect of Sodium Bicarbonate on Systolic Blood Pressure in CKD: A Systematic Review and Meta-Analysis

BACKGROUND

Individuals with CKD are at a higher risk of cardiovascular morbidity and mortality. Acidosis is positively correlated with CKD progression and elevated systolic BP. Sodium bicarbonate is an efficacious treatment of acidosis, although this may also increase systolic BP. In this systematic review and meta-analysis, we summarize the evidence evaluating systolic BP and antihypertensive medication change (which may indicate systolic BP change) in response to sodium bicarbonate therapy in individuals with CKD.

METHODS

Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, Cochrane Central Register of Controlled Trials, and World Health Organization (WHO) trials registry databases were searched for randomized control trials where sodium bicarbonate was compared with placebo/usual care in CKD stage G1-5 non-dialysis-dependent populations. Random effects meta-analyses were used to evaluate changes in systolic BP and BP-modifying drugs after sodium bicarbonate intervention.

RESULTS

Fourteen randomized control trials (2110 individuals, median follow-up 27 [interquartile range 97] weeks, mean age 60 [SD 10] years, mean systolic BP 136 [SD 17] mm Hg, mean eGFR 38 [SD 10] ml/min, mean serum bicarbonate 22 [SD 4] mmol/L) were eligible for inclusion. Meta-analysis suggested that sodium bicarbonate did not influence systolic BP in individuals with CKD stage G1-5. Results were consistent when stratifying by dose of sodium bicarbonate or duration of intervention. Similarly, there was no significant increase in the use of antihypertensive medication or diuretics in individuals taking sodium bicarbonate, whereas there was a greater decrease in antihypertensive medication use in individuals taking sodium bicarbonate compared with controls.

CONCLUSIONS

Our results suggest, with moderate certainty, that sodium bicarbonate supplementation does not adversely affect systolic BP in CKD or negatively influence antihypertensive medication requirements.

Diet and Metabolism in CKD-Related Metabolic Acidosis

Metabolic acidosis is a common complication in patients with chronic kidney disease that occurs when the daily nonvolatile acid load produced in metabolism cannot be excreted fully by the kidney. A reduction in urine net acid excretion coupled with a high nonvolatile acid load may play a role in its pathogenesis. Diet is important in generation of the nonvolatile acid load. Acids are produced from metabolism of dietary protein and from the endogenous production of organic anions from neutral precursors. Acids can be balanced by alkali precursors ingested in the diet in the form of combustible organic anions. These typically are reflected indirectly by the excess of mineral cations to mineral anions in a food or diet. These principles underscore widely used methods to estimate the nonvolatile acid load from dietary intake using formulas such as the net endogenous acid production equation and the potential renal acid load equation. Empiric data largely validate these paradigms with high net endogenous acid production and potential renal acid load contributed by foods such as protein, grains, and dairy, and low net endogenous acid production and potential renal acid load contributed by fruits and vegetables along with corresponding dietary patterns. Although further studies are needed to understand the health benefits of altering nonvolatile acid load via diet, this review provides a detailed assessment on our current understanding of the role of diet in chronic kidney disease-related acidosis, providing an updated resource for researchers and clinicians.

Hyperkalemia: Prevalence, Predictors and Emerging Treatments

It is well established that an elevated potassium level (hyperkalemia) is associated with a risk of adverse events including morbidity, mortality and healthcare system cost. Hyperkalemia is commonly encountered in many chronic conditions including kidney disease, diabetes and heart failure. Furthermore, hyperkalemia may result from the use of renin-angiotensin-aldosterone system inhibitors (RAASi), which are disease-modifying treatments for these conditions. Therefore, balancing the benefits of optimizing treatment with RAASi while mitigating hyperkalemia is crucial to ensure patients are optimally treated. In this review, we will briefly discuss the definition, causes, epidemiology and consequences of hyperkalemia. The majority of the review will be focused on management of hyperkalemia in the acute and chronic setting, emphasizing contemporary approaches and evolving data on the relevance of dietary restriction and the use of novel potassium binders.

Preclinical and Clinical Evidence of Effect of Acid on Bone Health

Acid can have ill effect on bone health in the absence of frank clinical acidosis but affecting the bone mioneral matrix and bone cells via complex pathways botyh ascute;y and chronically. While the reaction of bone to an acid load is conserved in evolution and is adaptive, the capacity can be overwhelmed resulting in dire consequences. The preclinical an clincl evidence of the acdi effect on bone is very convincing and the clinical evidence in both association and interventiopn studies are also quite credible, The adverse effects of acid on bone is underappreoicated, under-investigated, and the potential benefits of alkali therapy is not generrally known.

Clinical Consequences of Metabolic Acidosis-Muscle

Metabolic acidosis is common in people with chronic kidney disease and can contribute to functional decline, morbidity, and mortality. One avenue through which metabolic acidosis can result in these adverse clinical outcomes is by negatively impacting skeletal muscle; this can occur through several pathways. First, metabolic acidosis promotes protein degradation and impairs protein synthesis, which lead to muscle breakdown. Second, metabolic acidosis hinders mitochondrial function, which decreases oxidative phosphorylation and reduces energy production. Third, metabolic acidosis directly limits muscle contraction. The purpose of this review is to examine the specific mechanisms of each pathway through which metabolic acidosis affects muscle, the impact of metabolic acidosis on physical function, and the effect of treating metabolic acidosis on functional outcomes.

Importance of Metabolic Acidosis as a Health Risk in Chronic Kidney Disease

Human kidneys are well adapted to excrete the daily acid load from diet and metabolism in order to maintain homeostasis. In approximately 30% of patients with more advanced stages of CKD, these homeostatic processes are no longer adequate, resulting in metabolic acidosis. Potential deleterious effects of chronic metabolic acidosis in CKD, including muscle wasting, bone demineralization, hyperkalemia, and more rapid progression of CKD, have been well cataloged. Based primarily upon concerns related to nutrition and bone disease, early Kidney Disease Outcomes Quality Initiative guidelines recommended treating metabolic acidosis with alkali therapy targeting a serum bicarbonate ≥22 mEq/L. More recent guidelines have suggested similar targets based upon potential slowing of CKD progression. However, appropriately powered, long-term, randomized controlled trials to study efficacy and safety of alkali therapy for these outcomes are largely lacking. As a result, practice among physicians varies, underscoring the complexity of treatment of chronic metabolic acidosis in real-world CKD practice. Novel treatment approaches and rigorous phase 3 trials may resolve some of this controversy in the coming years. Metabolic acidosis is an important complication of CKD, and where it "falls" in the priority schema of CKD care will depend upon the generation of strong clinical evidence.

Serum bicarbonate levels and gait abnormalities in older adults: a cross-sectional study

Metabolic acidosis is associated with impaired physical function in patients with chronic kidney disease (CKD) and older adults. However, whether acidosis is associated with gait abnormalities has received little attention. In a cohort of 323 community-dwelling adults ≥ 65 years old who underwent quantitative gait analysis, we examined associations of serum bicarbonate with eight individual gait variables. After multivariable adjustment, participants in the lowest bicarbonate tertile (< 25 mEq/L) had 8.6 cm/s slower speed (95% confidence interval [CI] 3.2–13.9), 7.9 cm shorter stride length (95% CI 3.5–12.2), and 0.03 s longer double support time (95% CI 0.002–0.1) compared with those in the middle tertile (25–27 mEq/L). Furthermore, lower bicarbonate levels were associated with more severe gait abnormalities in a graded manner. After further adjustment for possible mediating factors, associations were attenuated but remained significant. Among participants with CKD, associations were of similar or greater magnitude compared with those without CKD. Factor analysis was performed to synthesize the individual gait variables into unifying domains: among the pace, rhythm, and variability domains, lower serum bicarbonate was associated with worse performance in pace. In sum, lower serum bicarbonate was independently associated with worse performance on several quantitative measures of gait among older adults.

Association of metabolic acidosis with fractures, falls, protein-calorie malnutrition, and failure to thrive in patients with chronic kidney disease

Background

The risk of adverse geriatric outcomes such as falls and fractures is high among patients with chronic kidney disease (CKD). Metabolic acidosis is associated with protein catabolism and bone loss in experimental animal and human studies. We sought to quantify the independent association of metabolic acidosis with adverse muscle, bone, and functional outcomes in a large U.S. community-based cohort.

Methods

The Optum's de-identified Integrated Claims-Clinical dataset of US patients (2007-2017) was used to generate a cohort of patients with non-dialysis-dependent CKD who had eGFR &gt;10 to &lt;60 mL/min/1.73 m2 and 2 serum bicarbonate values 12 to &lt;22 mmol/L or 22-29 mmol/L. The primary outcomes were failure to thrive, protein-calorie malnutrition, and fall or fracture. Cox proportional hazards models were used for the primary outcomes for up to 10 years, while logistic regression models were used at 2 years.

Results

51,558 patients qualified for the study, with a median (IQR) follow-up time of 4.2 (2.5-5.8) years. Over a ≤ 10-year period, for each 1-mmol/L increase in serum bicarbonate, the hazard ratios (adjusted for age, sex, race, eGFR, serum albumin, hemoglobin, diabetes and cardiovascular comorbidities) for failure to thrive, protein-calorie malnutrition, and fall or fracture were 0.91 (95% confidence interval [CI], 0.90-0.92), 0.91 (95% CI, 0.90-0.92), and 0.95 (95% CI, 0.95-0.96), all P &lt; 0.001, respectively.

Conclusions

The presence and severity of metabolic acidosis was a significant, independent risk factor for failure to thrive, protein-calorie malnutrition, and fall or fracture in this large community cohort of patients with stage 3-5 CKD.

Muscle-bone axis in children with chronic kidney disease: current knowledge and future perspectives

Bone and muscle tissue are developed hand-in-hand during childhood and adolescence and interact through mechanical loads and biochemical pathways forming the musculoskeletal system. Chronic kidney disease (CKD) is widely considered as both a bone and muscle-weakening disease, eventually leading to frailty phenotype, with detrimental effects on overall morbidity. CKD also interferes in the biomechanical communication between two tissues. Pathogenetic mechanisms including systemic inflammation, anorexia, physical inactivity, vitamin D deficiency and secondary hyperparathyroidism, metabolic acidosis, impaired growth hormone/insulin growth factor 1 axis, insulin resistance, and activation of renin-angiotensin system are incriminated for longitudinal uncoordinated loss of bone mineral content, bone strength, muscle mass, and muscle strength, leading to mechanical impairment of the functional muscle-bone unit. At the same time, CKD may also interfere in the biochemical crosstalk between the two organs, through inhibiting or stimulating the expression of certain osteokines and myokines. This review focuses on presenting current knowledge, according to in vitro, in vivo, and clinical studies, concerning the pathogenetic pathways involved in the muscle-bone axis, and suggests approaches aimed at preventing bone loss and muscle wasting in the pediatric population. Novel therapeutic targets for preserving musculoskeletal health in the context of CKD are also discussed.

Acidosis, cognitive dysfunction and motor impairments in patients with kidney disease

Metabolic acidosis, defined as a plasma or serum bicarbonate concentration <22 mmol/L, is a frequent consequence of chronic kidney disease (CKD) and occurs in ~10–30% of patients with advanced stages of CKD. Likewise, in patients with a kidney transplant, prevalence rates of metabolic acidosis range from 20% to 50%. CKD has recently been associated with cognitive dysfunction, including mild cognitive impairment with memory and attention deficits, reduced executive functions and morphological damage detectable with imaging. Also, impaired motor functions and loss of muscle strength are often found in patients with advanced CKD, which in part may be attributed to altered central nervous system (CNS) functions. While the exact mechanisms of how CKD may cause cognitive dysfunction and reduced motor functions are still debated, recent data point towards the possibility that acidosis is one modifiable contributor to cognitive dysfunction. This review summarizes recent evidence for an association between acidosis and cognitive dysfunction in patients with CKD and discusses potential mechanisms by which acidosis may impact CNS functions. The review also identifies important open questions to be answered to improve prevention and therapy of cognitive dysfunction in the setting of metabolic acidosis in patients with CKD.

Oral sodium bicarbonate in people on haemodialysis: a randomised controlled trial

Background

Adverse events and mortality tend to cluster around dialysis sessions, potentially due to the impact of the saw-toothed profile of uraemic toxins such as potassium, peaking pre-dialysis and rapidly dropping during dialysis. Acidosis could be contributing to this harm by exacerbating a rise in potassium. The objectives of this study were to investigate the effects of oral bicarbonate treatment on reducing inter-dialytic potassium gain as well as other clinical consequences of preserving muscle mass and function and reducing intradialytic arrhythmia risk in people on haemodialysis.

Methods

Open-label randomised controlled trial in a single-centre (London, UK). Forty-three clinically stable adults on haemodialysis were recruited, with a 6 month average pre-dialysis serum bicarbonate level < 22 mmol/l and potassium > 4 mmol/l. Thirty-three participants completed the study. Oral sodium bicarbonate tablets titrated up to a maximum of 3 g bd (6 g total) in intervention group for 12 weeks versus no treatment in the control group. Outcomes compared intervention versus non-intervention phases in the treated group and equivalent time points in the control group: pre- and post-dialysis serum potassium; nutritional assessments: muscle mass and handgrip strength and electrocardiograms (ECGs) pre and post dialysis.

Results

Participants took an average of 3.7 ± 0.5 g sodium bicarbonate a day. In the intervention group, inter-dialytic potassium gain was reduced from 1.90 ± 0.60 to 1.69 ± 0.49 mmol/l (p = 0.032) and pre-dialysis potassium was reduced from 4.96 ± 0.62 to 4.79 ± 0.49 mmol/l without dietary change. Pre-dialysis bicarbonate increased from 18.15 ± 1.35 to 20.27 ± 1.88 mmol/l, however with an increase in blood pressure. Nutritionally, lean tissue mass was reduced in the controls suggesting less catabolism in the intervention group. There was no change in ECGs. Limitations are small sample size and unblinded study design lacking a placebo, with several participants failing to achieve the target of 22 mmol/l serum bicarbonate levels due mainly to tablet burden.

Conclusion

Oral sodium bicarbonate reduced bicarbonate loss and potassium gain in the inter-dialytic period, and may also preserve lean tissue mass.

Trial registration

The study was registered prospectively on 06/08/2015 with EU Clinical Trials Register EudraCT number 2015-001439-20.

Effect of Oral Sodium Bicarbonate Treatment on 24-Hour Ambulatory Blood Pressure Measurements in Patients With Chronic Kidney Disease and Metabolic Acidosis

Background: Sodium bicarbonate supplementation is a mainstay in the treatment of metabolic acidosis in patients with chronic kidney disease (CKD). Recent studies showed reduction of progression of CKD and reduced all-cause mortality. However, additional sodium loading could worsen arterial hypertension, a well-known contributor to progression of CKD. This patient-relevant and economically negative side effect is under-studied in prospective studies up until now.

Objective: The aim of this study was to analyze the effect of sodium bicarbonate treatment on arterial blood pressure at baseline and after 8 weeks.

Methods: The SoBic study is an ongoing randomized controlled trial, in which patients with CKD receive either a high dose of oral sodium bicarbonate or a rescue treatment, if necessary. We used standardized office blood pressure and 24-hour ambulatory blood pressure monitoring (24h-ABPM). Regression models were adjusted for estimated glomerular filtration rate and change of antihypertensives.

Results: 47 subjects were enrolled and the mean age was 57 (±14.6) years and 18 (38%) were female. In 43 randomized subjects with sufficiently performed 24h-ABPM neither systolic 24h-ABPM (2.522; 95%CI: −2.364, 7.408; mmHg) nor diastolic 24h-ABPM (0.868; 95%CI: −2.411, 4.147; mmHg) was affected by study group allocation. When looking at the effect of individual sodium bicarbonate dose on 24h-ABPM, the fully adjusted model suggested an increase of 0.047 (95%CI: −0.026, 0.119) mmHg by each mg/kg per day increase of sodium bicarbonate dose.

Conclusion: Sodium bicarbonate supplementation over 8 weeks did not significantly increase blood pressure measured by 24h-ABPM in CKD patients.

Trial Registration: EUDRACT Number: 2012-001824-36; 12/07/2012 (https://www.clinicaltrialsregister.eu).

Fatigue in CKD: Epidemiology, Pathophysiology, and Treatment

Fatigue is a commonly reported and debilitating symptom among patients with CKD, yet little is known about its epidemiology, pathogenesis, and treatment. Various measurement tools have been used in published studies to identify and quantify fatigue. These include several single-item measures embedded in longer questionnaires for assessing depression, quality of life, or symptom burden in patients with kidney disease. Approximately 70% of patients with CKD report fatigue, with up to 25% reporting severe symptoms. Patient-reported fatigue is associated with death, dialysis initiation, and hospitalization among individuals with CKD. The pathophysiology is multifactorial and likely includes decreased oxygen delivery and increased reliance on anaerobic metabolism, thus generating lactic acidosis in response to exertion; the effects of chronic metabolic acidosis and hyperphosphatemia on skeletal muscle myocytes; protein-energy wasting and sarcopenia; and depression. Physical activity has been shown to improve fatigue in some small but promising trials, and so should be recommended, given the additional benefits of exercise. Targeting higher hemoglobin levels with erythropoiesis-stimulating agents may improve fatigue, but potential adverse cardiovascular effects preclude their use to solely treat fatigue without the presence of another indication. Current guidelines recommend cautious individualization of hemoglobin targets for those at low cardiovascular risk who still experience fatigue or functional limitation despite a hemoglobin level of 10 g/dl. Sodium bicarbonate supplementation for the treatment of metabolic acidosis may also improve functional status. Selective serotonin reuptake inhibitors have not been consistently shown to improve fatigue in patients with kidney disease, but an ongoing trial will evaluate the effect of alternative antidepressant drug and behavioral activation therapy on fatigue in patients with CKD. Overall, more research is needed to further clarify underlying mechanisms of fatigue and identify effective, targeted treatments for patients with CKD.

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

Background

Metabolic acidosis is a complication of chronic kidney disease (CKD) that increases risk of CKD progression, and causes bone demineralization and muscle protein catabolism. Patients with diabetes are prone to metabolic acidosis and functional limitations that decrease quality of life. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis. This post hoc subgroup analysis evaluated effects of veverimer on metabolic acidosis and physical function among patients with diabetes.

Methods

This was a Phase 3, multicenter, randomized, blinded, placebo-controlled trial in 196 patients with CKD (estimated glomerular filtration rate 20–40 mL/min/1.73 m²) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo.

Results

At Week 52, veverimer-treated patients with diabetes (n = 70), had a significantly greater increase in mean serum bicarbonate than the placebo group (n = 57) (4.4 versus 2.9 mmol/L, P < 0.05). Patient-reported limitations of physical function on the Kidney Disease and Quality of Life-Physical Function Domain (e.g. walking several blocks and climbing a flight of stairs) improved significantly in the veverimer versus placebo group (+12.5 versus +0.3, respectively, P < 0.001) as did objective physical performance on the repeated chair stand test (P < 0.0001).

Conclusions

Few interventions for patients with diabetes and CKD have successfully improved quality of life or physical functioning. Our study demonstrated that veverimer effectively treated metabolic acidosis in patients with diabetes and CKD, and significantly improved how these patients felt and functioned.

Efficacy and Safety of Veverimer in the Treatment of Metabolic Acidosis Caused by Chronic Kidney Disease: A Meta-analysis

Metabolic acidosis is a common complication of chronic kidney disease (CKD). Veverimer is an orally administrated, free amine polymer with high capacity and binding selectivity to hydrochloric acid from the gastrointestinal tract. This study pooled the current evidence of the efficacy and safety of veverimer for the treatment of metabolic acidosis associated with CKD. We conducted a systematic literature search on PubMed, Embase, and Cochrane Central for relevant randomized controlled trials (RCTs) in June 2020. In this study, three RCTs with 548 patients were included in our analysis. The analysis revealed that veverimer was associated with increased bicarbonate level of patients (weight mean difference [WMD] 3.08, 95% confidence interval [CI] [2.40, 3.77], p < 0.001) and improved physical function compared with placebo measured by Kidney Disease and Quality of Life Short Form 36, question 3 (physical functioning domain) (KDQoL-PFD) score (WMD 5.25, 95% CI [1.58, 8.92], p = 0.005). For safety outcomes, both groups exhibited similar risks for developing headache, diarrhea, flatulence, and hyperkalemia. In conclusion, current clinical evidence indicates that veverimer is efficacious and safe against metabolic acidosis related to CKD compared with placebo. Further research comparing long-term veverimer use with traditional alkali therapy is needed.

Effect of Bicarbonate on Net Acid Excretion, Blood Pressure, and Metabolism in Patients With and Without CKD: The Acid Base Compensation in CKD Study

RATIONALE & OBJECTIVE

Patients with CKD are at elevated risk of metabolic acidosis due to impaired net acid excretion (NAE). Identifying early markers of acidosis may guide prevention in chronic kidney disease (CKD). This study compared NAE in participants with and without CKD, as well as the NAE, blood pressure (BP), and metabolomic response to bicarbonate supplementation.

STUDY DESIGN

Randomized order, cross-over study with controlled feeding.

SETTING & PARTICIPANTS

Participants consisted of 8 patients with CKD (estimated glomerular filtration rate 30-59mL/min/1.73m² or 60-70mL/min/1.73m² with albuminuria) and 6 patients without CKD. All participants had baseline serum bicarbonate concentrations between 20 and 28 mEq/L; they did not have diabetes mellitus and did not use alkali supplements at baseline.

INTERVENTION

Participants were fed a fixed-acid-load diet with bicarbonate supplementation (7 days) and with sodium chloride control (7 days) in a randomized order, cross-over fashion.

OUTCOMES

Urine NAE, 24-hour ambulatory BP, and 24-hour urine and plasma metabolomic profiles were measured after each period.

RESULTS

During the control period, mean NAE was 28.3±10.2 mEq/d overall without differences across groups (P=0.5). Urine pH, ammonium, and citrate were significantly lower in CKD than in non-CKD (P<0.05 for each). Bicarbonate supplementation reduced NAE and urine ammonium in the CKD group, increased urine pH in both groups (but more in patients with CKD than in those without), and increased; urine citrate in the CKD group (P< 0.2 for interaction for each). Metabolomic analysis revealed several urine organic anions were increased with bicarbonate in CKD, including 3-indoleacetate, citrate/isocitrate, and glutarate. BP was not significantly changed.

LIMITATIONS

Small sample size and short feeding duration.

CONCLUSIONS

Compared to patients without CKD, those with CKD had lower acid excretion in the form of ammonium but also lower base excretion such as citrate and other organic anions, a potential compensation to preserve acid-base homeostasis. In CKD, acid excretion decreased further, but base excretion (eg, citrate) increased in response to alkali. Urine citrate should be evaluated as an early and responsive marker of impaired acid-base homeostasis.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases and the Duke O'Brien Center for Kidney Research.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT02427594.

Hand Grip and Leg Muscle Strength in Hemodialysis Patients and Its Determinants

BACKGROUND

Chronic kidney disease is associated with chronic inflammation and progressive loss of peripheral muscle strength and the ability to exercise, and these changes are highly pronounced in patients receiving hemodialysis (HD). We evaluated hand grip strength (HGS) and leg muscle strength (LMS) in patients receiving HD and attempted to identify factors associated with muscle strength.

METHODS

We screened HGS (opposite the fistula side) and LMS (both sides) in HD patients at a single center (n = 112) by using digital hand and leg dynamometers (T.K.K. 5401 and 5710e/5715, Takei Scientific Instruments Co. Ltd., Niigata, Japan).

RESULTS

The mean age of patients was 62.6 years, and 73.2% of the patients were male. Diabetes was the cause of kidney failure in 50% of the patients, and the median HD vintage was 34 months. A total of 77.7% of patients reported that they participated in regular home-based exercise, and 29.5% of patients regularly participated in hospital-based resistance exercise. HGS and LMS showed good correlation (r = 0.715, P < 0.001). HGS (25.1 vs. 17.0 kg) and LMS (30.1 vs. 20.4 kg) were greater in males (P < 0.001 and P < 0.001, respectively) than in females. Older patients (≥ 60 years) showed less LMS than younger patients in both males and females (P = 0.012 and P = 0.037, respectively), but HGS did not differ according to age. Patients performing regular home- or hospital-based exercise showed higher HGS than those who did not exercise (24.2 vs. 18.6 kg, P = 0.011), but LMS was not significantly different (29.3 vs. 23.6 kg, P = 0.185). Multiple linear regression analysis proved that male sex, younger age, and any type of exercise were factors associated with improved HGS and LMS. Groups of older age (≥ 60 years), male sex, and shorter duration of HD (< median) benefitted more from exercise.

CONCLUSION

Sex, age, and exercise were the most important determinants of muscle strength in HD patients. We need to encourage patients to engage in regular home or group exercise from the beginning of dialysis and introduce new feasible forms of exercise for HD patients.

New insights into muscle function in chronic kidney disease and metabolic acidosis

PURPOSE OF REVIEW

: Sarcopenia, defined as decreased muscle mass or function, is prevalent in chronic kidney disease (CKD) increasing the risk of mobility impairment and frailty. CKD leads to metabolic acidosis (MA) and retention of uremic toxins contributing to insulin resistance and impaired muscle mitochondrial energetics. Here we focus on the central role of muscle mitochondrial metabolism in muscle function.

RECENT FINDINGS

: Mitochondrial dysfunction underlies muscle wasting and poor physical endurance in CKD. Uremic toxins accumulate in muscle disrupting mitochondrial respiration and enzymes. Changes in mitochondrial quantity, quality, and oxidative capacity contribute to mobility impairment in CKD. Major determinants of muscle mitochondrial function are kidney function, inflammation, and oxidative stress. In CKD, MA is the major determinant of muscle mitochondrial function. Metabolomics reveals defects in pathways linked to mitochondrial energy metabolism and acid-base homeostasis underlying insulin resistance in CKD.

SUMMARY

: Decreased mitochondrial capacity and quality control can impair muscle function contributing to decreased physical endurance. MA augments insulin resistance perpetuating the catabolic state underlying muscle wasting in CKD. Further studies are needed to investigate if targeting of MA improves muscle mitochondrial function and insulin resistance translating into meaningful improvements in physical endurance.

Metabolic Acidosis in CKD: A Review of Recent Findings

Metabolic acidosis is fairly common in patients with chronic kidney disease (CKD). The prevalence of metabolic acidosis increases with worsening kidney function and is observed in ∼40% of those with stage 4 CKD. For the past 2 decades, clinical practice guidelines have suggested treatment of metabolic acidosis to counterbalance adverse effects of metabolic acidosis on bone and muscle. Studies in animal models of CKD also demonstrated that metabolic acidosis causes kidney fibrosis. During the past decade, results from observational studies identified associations between metabolic acidosis and adverse kidney outcomes, and results from interventional studies support the hypothesis that treating metabolic acidosis with sodium bicarbonate preserves kidney function. However, convincing data from large-scale, double-blinded, placebo-controlled, randomized trials have been lacking. This review discusses findings from recent interventional trials of alkali therapy in CKD and new findings linking metabolic acidosis with cardiovascular disease in adults and CKD progression in children. Finally, a novel agent that treats metabolic acidosis in patients with CKD by binding hydrochloric acid in the gastrointestinal tract is discussed.

Exhausted Capacity of Bicarbonate Buffer in Renal Failure Diagnosed Using Point of Care Analyzer

BACKGROUND

Metabolic acidosis in patients with chronic kidney disease (CKD) is a common complication. A bicarbonate concentration in venous blood (V-HCO₃^-) is a key index for diagnosis and treatment initiation. The aim of our study is to evaluate usability of acid-base balance parameters of in blood taken simultaneously from peripheral artery and the vein.

METHODS

A total of 49 patients (median age 66 years [interquartile range IQR 45-75]), with CKD stage G4 or G5 were enrolled in this cross-sectional study. All patients were qualified for arteriovenous fistula creation in pre-dialysis period. The samples were taken during surgery, directly after dissection, and evaluated in a point of care testing analyzer. The arteriovenous difference in bicarbonate levels (Δ-HCO₃^-) was calculated. According to glomerular filtration rate (eGFR) the group was divided into Group A eGFR ≥ 10 mL/min/1.73 m²) and Group B eGFR < 10 mL/min/1.73 m²).

RESULTS

In Group A Δ-HCO₃^- was significantly higher compared to Group B. No such differences were observed in the case of V-HCO₃^-. Δ-HCO₃^- positively correlated with eGFR. The discriminative power of Δ-HCO₃^- for predicting eGFR < 10 mL/min/1.73 m² was 0.72 (95% confidence interval [CI] = 0.551-0.88; p = 0.01) which provided 67% sensitivity and 75% specificity. The best cut-off was 0.5 mmol/L.

CONCLUSIONS

The Δ-HCO₃^- lower than 0.5 mmol/L may be used as predictor of exhaust buffer capacity. The value of this tool should be tested in larger population.

A Systematic Review and Meta-Analysis on Effects of Bicarbonate Therapy on Kidney Outcomes

Aim

Preclinical studies suggest treatment of metabolic acidosis may slow chronic kidney disease (CKD) progression. This systematic review aimed to summarize evidence from randomized controlled trials (RCTs) concerning the benefits and risks of bicarbonate therapy on kidney outcomes.

Methods

Medline, EMBASE, and Cochrane databases were searched for RCTs with ≥3 months’ follow-up in patients with CKD (estimated glomerular filtration rate [eGFR] ≤60 ml/min per 1.73 m² and/or proteinuria) comparing the effects of sodium bicarbonate with placebo/no study medication on kidney outcomes. The primary outcome was change from baseline to last measurement in kidney function measured as either eGFR or creatinine clearance. Treatment effects were summarized using random-effects meta-analysis.

Results

Fifteen trials (2445 participants, median follow-up 12 months) were eligible for inclusion. Compared with placebo or no study medication, sodium bicarbonate retarded the decline in kidney function (standardized mean difference [SMD]: 0.26; 95% confidence interval [CI]: 0.13–0.40; I² = 50%, low certainty evidence), and reduced the risk of end-stage kidney failure (risk ratio [RR]: 0.53; 95% CI 0.32–0.89; I² = 69%, low certainty evidence). The effect of sodium bicarbonate on proteinuria (SMD: −0.09; 95% CI −0.27 to 0.09; I² = 28%, very low certainty evidence), systolic blood pressure (weighted mean difference [WMD]: −0.57 mm Hg; 95% CI −2.32 to 1.18; I² = 0%, low certainty evidence), all-cause death (RR: 0.81; 95% CI: 0.39–1.68; I² = 30%; very low certainty evidence) and edema (RR: 1.16; 95% CI: 0.90–1.50; I² = 28%; low certainty evidence) were uncertain.

Conclusion

Sodium bicarbonate may slow CKD progression. Adequately powered randomized trials are required to evaluate the benefits and risks of sodium bicarbonate in CKD.

Exercise intolerance in kidney diseases: physiological contributors and therapeutic strategies

Exertional fatigue, defined as the overwhelming and debilitating sense of sustained exhaustion that impacts the ability to perform activities of daily living, is highly prevalent in chronic kidney disease (CKD) and end-stage renal disease (ESRD). Subjective reports of exertional fatigue are paralleled by objective measurements of exercise intolerance throughout the spectrum of the disease. The prevalence of exercise intolerance is clinically noteworthy, as it leads to increased frailty, worsened quality of life, and an increased risk of mortality. The physiological underpinnings of exercise intolerance are multifaceted and still not fully understood. This review aims to provide a comprehensive outline of the potential physiological contributors, both central and peripheral, to kidney disease-related exercise intolerance and highlight current and prospective interventions to target this symptom. In this review, the CKD-related metabolic derangements, cardiac and pulmonary dysfunction, altered physiological responses to oxygen consumption, vascular derangements, and sarcopenia are discussed in the context of exercise intolerance. Lifestyle interventions to improve exertional fatigue, such as aerobic and resistance exercise training, are discussed, and the lack of dietary interventions to improve exercise tolerance is highlighted. Current and prospective pharmaceutical and nutraceutical strategies to improve exertional fatigue are also broached. An extensive understanding of the pathophysiological mechanisms of exercise intolerance will allow for the development of more targeted therapeutic approached to improve exertional fatigue and health-related quality of life in CKD and ESRD.

Mechanism of Action of Veverimer: A Novel, Orally Administered, Nonabsorbed, Counterion-Free, Hydrochloric Acid Binder under Development for the Treatment of Metabolic Acidosis in Chronic Kidney Disease

Current management of metabolic acidosis in patients with chronic kidney disease (CKD) relies on dietary intervention to reduce daily endogenous acid production or neutralization of retained acid with oral alkali (sodium bicarbonate, sodium citrate). Veverimer is being developed as a novel oral treatment for metabolic acidosis through removal of intestinal acid, resulting in an increase in serum bicarbonate. Veverimer is a free-amine polymer that combines high capacity and selectivity to bind and remove hydrochloric acid (HCl) from the gastrointestinal (GI) tract. In vitro studies demonstrated that veverimer had a binding capacity of 10.7 ± 0.4 mmol HCl per gram of polymer with significant binding capacity (>5 mmol/g) across the range of pH values found in the human GI tract (1.5-7). Upon protonation, veverimer bound chloride with high specificity but showed little or no binding of phosphate, citrate, or taurocholate (<1.5 mmol/g), which are all anions commonly found in the human GI tract. Administration of veverimer to rats with adenine-induced CKD and metabolic acidosis resulted in a significant increase in fecal chloride excretion and a dose-dependent increase in serum bicarbonate to within the normal range compared with untreated controls. Absorption, distribution, metabolism, and excretion studies in rats and dogs dosed with ¹⁴C-labeled veverimer showed that the polymer was not absorbed from the GI tract and was quantitatively eliminated in the feces. Acid removal by veverimer, an orally administered, nonabsorbed polymer, may provide a potential new treatment for metabolic acidosis in patients with CKD. SIGNIFICANCE STATEMENT: Metabolic acidosis is a complication of chronic kidney disease (CKD) as well as a cause of CKD progression. Veverimer is a high-capacity, selective, nonabsorbed, hydrochloric acid-binding polymer being developed as a treatment for metabolic acidosis. Veverimer binds and removes hydrochloric acid from the gastrointestinal tract, resulting in increased serum bicarbonate and the correction of metabolic acidosis. Veverimer is not an ion-exchange resin and does not deliver sodium or other counterions, and so it may be appropriate for patients with CKD with and without sodium-sensitive comorbidities.

Veverimer: An Emerging Potential Treatment Option for Managing the Metabolic Acidosis of CKD

Sodium bicarbonate is the mainstay treatment of the metabolic acidosis of chronic kidney disease but associated concerns center on administering sodium to patients with hypertension and sodium-retentive states. Veverimer (formerly referred to as TRC101), a drug candidate for which Tricida, Inc is seeking approval from the US Food and Drug Administration, is a novel nonabsorbable polymer that binds hydrogen cations and chloride anions in the gastrointestinal tract and then is excreted fecally, thereby increasing serum bicarbonate concentration without administering sodium. We examine the published evidence on the investigational use of veverimer in patients with chronic kidney disease and metabolic acidosis. We highlight the achieved increase in serum bicarbonate concentration without coadministering sodium, effects on physical functioning, and the safety record of the drug. We also scrutinize certain unanticipated findings: a lack of dose dependency in the increase in serum bicarbonate concentration observed and that despite the presumed large hydrogen chloride losses in feces, veverimer induces an isochloremic increase in serum bicarbonate concentration that is accompanied by a decrease in serum anion gap. We propose likely explanations for these puzzling findings and raise questions about veverimer's mode of action and its potential interaction with colonic bacterial flora. Additional work is required to fill these knowledge gaps that could have important clinical implications.

Spot urinary citrate-to-creatinine ratio is a marker for acid-base status in chronic kidney disease

Due to multiple compensating mechanisms, the serum bicarbonate concentration is a relatively insensitive marker of acid-base status; especially in chronic kidney disease (CKD). This is a major drawback that impairs the ability to diagnose acid excess or monitor alkali therapy. We postulated that it is more logical to measure the compensatory defense mechanism(s) rather than the defended parameter, which remains normal if the compensation is successful. Therefore, a retrospective cross-sectional study was performed in 1733 stone formers along with a prospective cross-sectional study of 22 individuals with normal kidney function and 50 patients in different stages of CKD. While serum bicarbonate was flat and did not fall below the reference range until near CKD stage 5, citrate excretion (24-hour urinary citrate excretion rate; urinary citrate-to-creatinine ratio, in the retrospective analysis, and spot urinary citrate-to-creatinine ratio in the prospective study) progressively and significantly declined starting from CKD stage 2. Following an acute acid load in 25 participants with a wide range of estimated glomerular filtration rates, the urinary citrate-to-creatinine ratio inversely and significantly associated with acid accumulation, whereas serum bicarbonate did not. We compared changes in serum bicarbonate and urinary citrate-to-creatinine ratio in response to alkali therapy in patients with CKD stage 3 or 4 started on potassium citrate in our kidney stone database. With alkali therapy, there was no change in serum bicarbonate, but the urinary citrate-to-creatinine ratio rose consistently in all patients adherent to potassium citrate therapy. Thus, the urinary citrate-to-creatinine ratio (the defense mechanism) is a potential easily implementable, pragmatic, and a superior parameter to serum bicarbonate (the defended entity) to assess acid-base status, and monitor alkali therapy. Additional studies are needed before a clinical test can be devised.

Advances in management of chronic metabolic acidosis in chronic kidney disease

PURPOSE OF REVIEW

Chronic metabolic acidosis is a common complication of chronic kidney disease (CKD) and is associated with adverse consequences, such as CKD progression and muscle wasting. We review the findings from recent clinical trials that have examined the effects of sodium bicarbonate therapy and veverimer in patients with CKD and chronic metabolic acidosis.

RECENT FINDINGS

There are four recent clinical trials on chronic metabolic acidosis of CKD. In a pilot, cross-over study, 6 weeks of sodium bicarbonate therapy improved vascular endothelial function, measured by brachial artery flow-mediated dilation. In a single-center, randomized, open-label study, 6 months of sodium bicarbonate therapy increased muscle mass and lean body mass, and preserved kidney function. The other two clinical trials (phase 1/2 and phase 3 studies) examined the effects of veverimer, which is a hydrochloric acid binder. The phase 3 study showed that 12-weeks of veverimer increased serum bicarbonate levels and might improve physical function. The effects of veverimer on CKD progression, physical function and cardiovascular endpoints as well as its long-term safety are yet to be determined.

SUMMARY

Recent studies suggest that sodium bicarbonate therapy may improve vascular endothelial function and muscle mass, and preserve renal function. Veverimer increases serum bicarbonate level and could be a potential new therapeutic option for treating chronic metabolic acidosis.

Successful correction of metabolic acidosis is difficult to achieve in chronic kidney disease

INTRODUCTION

Metabolic acidosis (MA) is a common complication of chronic kidney disease (CKD) and is associated with numerous adverse effects, which is why its correction is highly recommended. Oral sodium bicarbonate is the current treatment of choice.

OBJECTIVES

To describe the prevalence of MA in advanced CKD patients and to determine the clinical and biochemical characteristics associated with its successful correction.

MATERIAL AND METHODS

Retrospective, observational cohort study in adult patients with CKD stage 4-5. The inclusion criteria were: not being treated with alkali therapy at the time of inclusion, and to have at least three consecutive glomerular filtration rate (GFR) measurements and biochemical parameters during a minimum follow-up period of 3 months. Incident patients with serum bicarbonate<22 mEq/l were included in the follow-up study and treated with oral sodium bicarbonate. Correction was considered successful when more than half of the samples and the mean bicarbonate levels during individual follow-up were≥22 mEq/l.

RESULTS

The study group consisted of 969 patients (age 65±14 years, 507 males) with a mean GFR of 14.8±4.5ml/min/1.73 m². At baseline, 530 patients (55%) had serum bicarbonate<22mEq/l. They were treated with sodium bicarbonate and followed for 15 months. Satisfactory correction of MA was only achieved in 133 patients (25%). By multivariate logistic regression analysis, the main characteristics of patients with adequate control of MA were: age (OR=1.03; 95% CI 1.01 - 1.05), baseline GFR (OR=1.07; 1.02 - 1.12), and treatment with proton-pump inhibitors (OR=1.61; 95% CI 1.06 - 2.44). Patients who achieved successful correction of MA showed slower CKD progression (-1.67±3.71 vs -4.36±4.56ml/min/1.73 m²/year, P<.0001), and lower average serum potassium concentration (5.1±0.5 vs 5.3±0.5, P<.0001) than those who did not. However, there were no differences in the hospitalisation or mortality rate.

CONCLUSION

MA is a common complication of advanced CKD but difficult to manage with current therapies. Due to the significant potential benefit of controlling MA, new, more effective therapies should be further researched.

A Randomized Trial Comparing the Safety, Adherence, and Pharmacodynamics Profiles of Two Doses of Sodium Bicarbonate in CKD: the BASE Pilot Trial

BACKGROUND

Oral sodium bicarbonate (NaHCO₃) may preserve kidney function in CKD, even if initiated when serum bicarbonate concentration is normal. Adequately powered trials testing this hypothesis have not been conducted, partly because the best dose for testing is unknown.

METHODS

This multicenter pilot trial assessed the safety, tolerability, adherence, and pharmacodynamics of two doses of NaHCO₃ over 28 weeks in adults with eGFR 20-44 or 45-59 ml/min per 1.73 m² with urinary albumin/creatinine (ACR) ≥50 mg/g and serum bicarbonate 20-28 meq/L. We randomly assigned 194 participants from ten clinical sites to receive higher-dose (HD-NaHCO₃; 0.8 meq/kg of lean body wt per day; n=90) or lower-dose (LD-NaHCO₃; 0.5 meq/kg of lean body wt per day; n=52) NaHCO₃ or matching placebo (n=52). The dose was adjusted depending on side effects. The prescribed dose at week 28 was the primary outcome; a dose was considered acceptable for a full-scale trial if ≥67% of participants were on full-dose and ≥80% were on ≥25% of the per-protocol dose.

RESULTS

Mean±SD baseline eGFR was 36±9 ml/min per 1.73 m², serum bicarbonate was 24±2 meq/L, and median (IQR) ACR was 181 (25-745) mg/g. Both doses were well tolerated without significant changes in BP, weight, or serum potassium. The proportions of adverse events and hospitalizations were similar across the groups. Consequently, 87% in HD-NaHCO₃, 96% in LD-NaHCO₃, and 87% in placebo were on full dose at week 28; and 91% in HD-NaHCO₃, 98% in LD-NaHCO₃, and 92% in placebo were on ≥25% of the per-protocol dose. Mean urinary ammonium excretion was 25% lower and serum bicarbonate concentration was 1.3 meq/L higher in HD-NaHCO₃ compared with LD-NaHCO₃ at week 28. However, mean ACR increased by 12% in the lower-dose group and 30% in the higher-dose group.

CONCLUSIONS

Both NaHCO₃ doses were well tolerated over 28 weeks with no significant difference in adverse events or hospitalization compared with placebo. The higher dose lowered urinary ammonium excretion and increased serum bicarbonate more than the lower dose but was associated with a greater increase in ACR. The higher 0.8 meq/kg of lean body wt per day dose of NaHCO₃ may be a reasonable choice for future trials.

Effects of Sodium Bicarbonate in CKD Stages 3 and 4: A Randomized, Placebo-Controlled, Multicenter Clinical Trial

RATIONALE & OBJECTIVE

Metabolic acidosis associated with chronic kidney disease (CKD) may contribute to muscle dysfunction and bone disease. We aimed to test whether treatment with sodium bicarbonate improves muscle and bone outcomes.

STUDY DESIGN

Multicenter, randomized, placebo-controlled, clinical trial.

SETTING & PARTICIPANTS

149 patients with CKD stages 3 and 4 between July 2011 and April 2016 at 3 centers in Cleveland, OH, and the Bronx, NY.

INTERVENTION

Sodium bicarbonate (0.4 mEq per kg of ideal body weight per day) (n=74) or identical-appearing placebo (n=75).

OUTCOMES

Dual primary outcomes were muscle function assessed using sit-to-stand test and bone mineral density. Muscle biopsies were performed at baseline and 2 months. Participants were seen at baseline and 2, 6, 12, and 24 months.

RESULTS

Mean baseline serum bicarbonate level was 24.0±2.2 (SD) mEq/L and mean baseline estimated glomerular filtration rate was 36.3±11.2mL/min/1.73m². Baseline characteristics did not differ between groups. Mean serum bicarbonate levels in the intervention arm during follow-up were 26.4±2.2, 25.5±2.3, 25.6±2.6, and 24.4±2.8 mEq/L (at 2, 6, 12, and 24 months). These were significantly higher than in the placebo group (P<0.001). Compared to the placebo group, participants randomly assigned to sodium bicarbonate treatment had no significant differences in sit-to-stand time (5 repetitions: P=0.1; and 10 repetitions P=0.07) or bone mineral density (P=0.3). Sodium bicarbonate treatment caused a decrease in serum potassium levels that was of borderline statistical significance (P=0.05). There were no significant differences in estimated glomerular filtration rates, blood pressure, weight, serious adverse events, or levels of muscle gene expression between the randomly assigned groups.

LIMITATIONS

Initial mean serum bicarbonate level was in the normal range.

CONCLUSIONS

Sodium bicarbonate therapy in patients with CKD stages 3 and 4 significantly increases serum bicarbonate and decreases potassium levels. No differences were found in muscle function or bone mineral density between the randomly assigned groups. Larger trials are required to evaluate effects on kidney function.

FUNDING

National Institutes of Health grant.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT01452412.

NaHCO3 Dilates Mouse Afferent Arteriole Via Na+/HCO3- Cotransporters NBCs

Sodium bicarbonate has long been used to treat chronic kidney disease. It has been demonstrated to slow the decline in glomerular filtration rate in chronic kidney disease patient; however, the mechanisms are not completely understood. We hypothesized that NaHCO₃ dilates afferent arterioles (Af-Art) by stimulating nitric oxide (NO) release mediated by the Na⁺/HCO₃^- cotransporter (NBC) contributing to the elevation in glomerular filtration rate. Isolated microperfused mouse renal Af-Art, preconstricted with norepinephrine (1 µmol/L), dilated 45±2% (n=6, P<0.05) in response to NaHCO₃ (44 mmol/L). Whereas, NaCl solution containing the same Na⁺ concentration was not effective. The mRNA for NBCn1 and NBCe1 were detected in microdissected Af-Art using reverse transcription-polymerase chain reaction and quantitative polymerase chain reaction. The Af-Art intracellular pH measured with 2',7'-bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein, acetoxymethyl ester increased significantly by 0.29±0.02 (n=6; P<0.05) in the presence of NaHCO₃, which was blunted by N-cyanosulphonamide compound (S0859) that is an inhibitor of the NBC family. After clamping the intracellular pH with 10 μM nigericin, changing the bath solution pH from 7.4 to 7.8 still dilates the Af-Art by 53±4% (n=7; P<0.005) and increases NO generation by 22±3% (n=7; P<0.005). Both pH-induced NO generation and vasodilation were blocked by L-NG-Nitroarginine Methyl Ester. NaHCO₃ increased NO generation in Af-Art by 19±4% (n=5; P<0.005) and elevated glomerular filtration rate in conscious mice by 36% (233 versus 318 ul/min; n=9-10; P<0.0001). S0859 and L-NG-nitroarginine methyl ester blocked NaHCO₃-induced increases in NO generation and vasodilation. We conclude that NBCn1 and NBCe1 are expressed in Af-Art and that NaHCO₃ dilates Af-Art via NBCs mediated by NO that increases the glomerular filtration rate.

Effects of Treatment of Metabolic Acidosis in CKD: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Metabolic acidosis is associated with progression of CKD and has significant adverse effects on muscle and bone. A systematic review and meta-analysis was conducted to evaluate the benefits and risks of metabolic acidosis treatment with oral alkali supplementation or a reduction of dietary acid intake in those with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

MEDLINE, Embase, and Cochrane CENTRAL were searched for relevant trials in patients with stage 3-5 CKD and metabolic acidosis (<22 mEq/L) or low-normal serum bicarbonate (22-24 mEq/L). Data were pooled in a meta-analysis with results expressed as weighted mean difference for continuous outcomes and relative risk for categorical outcomes with 95% confidence intervals (95% CIs), using a random effects model. Study quality and strength of evidence were assessed using Cochrane risk of bias and the Grading of Recommendations Assessment, Development and Evaluation criteria.

RESULTS

Fourteen clinical trials were included (n=1394 participants). Treatment of metabolic acidosis with oral alkali supplementation or a reduction of dietary acid intake increased serum bicarbonate levels (14 studies, 1378 patients, mean difference 3.33 mEq/L, 95% CI, 2.37 to 4.29) and resulted in a slower decline in eGFR (13 studies, 1329 patients, mean difference -3.28 ml/min per 1.73 m2, 95% CI, -4.42 to -2.14; moderate certainty) and a reduction in urinary albumin excretion (very-low certainty), along with a reduction in the risk of progression to ESKD (relative risk, 0.32; 95% CI, 0.18 to 0.56; low certainty). Oral alkali supplementation was associated with worsening hypertension or the requirement for increased antihypertensive therapy (very-low certainty).

CONCLUSIONS

Low-to-moderate certainty evidence suggest that oral alkali supplementation or a reduction in dietary acid intake may slow the rate of kidney function decline and potentially reduce the risk of ESKD in patients with CKD and metabolic acidosis.

Veverimer versus placebo in patients with metabolic acidosis associated with chronic kidney disease: a multicentre, randomised, double-blind, controlled, phase 3 trial

BACKGROUND

Patients with advanced chronic kidney disease lose the capacity to fully excrete endogenous acid, resulting in chronic metabolic acidosis that increases the risk of disease progression and causes muscle catabolism and bone resorption. Veverimer, a non-absorbed, counterion-free, polymeric drug, selectively binds and removes hydrochloric acid from the gastrointestinal lumen, unlike current oral sodium bicarbonate therapy for metabolic acidosis that only neutralises accumulated acid. We assessed the efficacy and safety of veverimer as a treatment for metabolic acidosis in patients with chronic kidney disease.

METHODS

We did a multicentre, parallel, randomised, double-blind, placebo-controlled study at 37 sites (hospitals and specialty clinics) in Bulgaria, Croatia, Georgia, Hungary, Serbia, Slovenia, Ukraine, and the USA. Eligible participants were patients aged 18-85 years with non-dialysis-dependent chronic kidney disease (estimated glomerular filtration rate of 20-40 mL/min per 1·73 m²) and metabolic acidosis (serum bicarbonate concentration of 12-20 mmol/L). Patients were randomly assigned (4:3) to veverimer 6 g/day or placebo for 12 weeks while they consumed their typical diet. Both drugs were taken as oral suspensions in water with lunch. Randomisation was done by study site personnel with a computer-generated randomisation code with balanced permuted blocks (block size of seven) and stratified by baseline bicarbonate (≤18 mmol/L vs >18 mmol/L). Patients and investigators were masked to treatment allocation; however, because the appearance of placebo differed from veverimer, a non-masked site staff member who had no other role in the study dispensed, prepared, and supervised dosing of the study drugs. The composite primary efficacy endpoint was the difference (veverimer-placebo) in the proportion of patients achieving at week 12 either an increase of 4 mmol/L or more from baseline in serum bicarbonate concentration or serum bicarbonate in the normal range of 22-29 mmol/L, assessed in the modified intention-to-treat population (all patients with a baseline and at least one post-baseline serum bicarbonate value). Patients fasted for at least 4 h (consuming only water) before measurements of bicarbonate. Safety was assessed in all patients who received any amount of study drug. This trial is registered with ClinicalTrials.gov, number NCT03317444.

FINDINGS

Between Sept 26, 2017, and Feb 9, 2018, we randomly assigned 124 participants to veverimer and 93 to placebo. The composite primary endpoint was met by 71 (59%) of 120 patients in the veverimer group versus 20 (22%) of 89 patients in the placebo group (a difference of 37%, 95% CI 23-49; p<0·0001). The most common body system in which adverse events in the veverimer group occurred was gastrointestinal; of these, non-treatment limiting diarrhoea was the most common event (11 [9%] vs three [3%] in the veverimer and placebo groups, respectively). The most common treatment-related adverse events were gastrointestinal (diarrhoea, flatulence, nausea, and constipation) occurring in 16 (13%) patients with veverimer and five (5%) patients with placebo. Two deaths occurred during the study, both in the placebo group (unstable angina and pneumonia).

INTERPRETATION

Veverimer effectively and safely corrected metabolic acidosis. Longer-term studies are warranted to assess the effects of veverimer on physical functioning and to assess other deleterious consequences of metabolic acidosis including progression of chronic kidney disease and bone health.

FUNDING

Tricida.

Aiming for the optimal bicarbonate prescription for maintenance hemodialysis therapy in end-stage renal disease

INTRODUCTION

Acidemia and alkalemia, as a result of gradual depletion of the body's buffers followed by rapid repletion during hemodialysis (HD), are linked to adverse consequences. We examined the acid-base status with dialysis bath of higher bicarbonate (HC03^- ) concentration or standard HC03^- bath plus oral HC03^- supplementation.

METHODS

A total of 60 stable HD patients (pts) were evaluated according to their pre-dialysis acid-base status both before the first and the second session of the week dialyzed against standard base dialysate of 35 mmol/L. Those who presented predialysis HC03^- <22 mmol/L (25 pts) were assigned to dialysis against bath of increased HC03^- levels (37 mmol/L) for 2 weeks (period A) and subsequently to dialysis with the standard dialysate bath plus daily oral sodium bicarbonate at a dose of 5 g/day for 2 weeks (period B). Pre and post-dialysis acid-base status at each study period and relevant laboratory tests were recorded.

FINDINGS

Pre-dialysis acid-base values were similar between the first and the second dialysis session. Twenty-five points had pre-dialysis pH <7.35, while 42 (the younger ones) presented pre-dialysis HC03^- <22 mmol/L. After dialysis session 18 pts had pH >7.45. Comparing the two study periods, interdialytic weight was similar, pre-dialysis HC03^- levels were improved with oral bicarbonate, while post-dialysis HC03^- were higher during period A. Three pts could not tolerate the symptoms of alkalemia during period A.

DISCUSSION

The impact of conventional HC03^- concentrations of 35 mmol/L results in a considerable degree of pre-dialysis acidemia. Increasing the HC03^- in bath results in more prominent post-dialysis alkalemia, however, it is not sufficient to maintain acid-base status during the interdialytic period. Oral bicarbonate supplement at a dose of 5 g/day (divided in three daily doses) results in a more balanced acid-base status, avoiding post-dialysis alkalemia.

Chronic Kidney Disease and Dietary Measures to Improve Outcomes

Chronic kidney disease is an ongoing deterioration of renal function that often progresses to end-stage renal disease. Management goals in children include slowing disease progression, prevention and treatment of complications, and optimizing growth, development, and quality of life. Nutritional management is critically important to achieve these goals. Control of blood pressure, proteinuria, and metabolic acidosis with dietary and pharmacologic measures may slow progression of chronic kidney disease. Although significant progress in management has been made, further research is required to resolve many outstanding controversies. We review recent developments in pediatric chronic kidney disease, focusing on dietary measures to improve outcomes.

Tolerance to Sodium in Patients With CKD-Induced Metabolic Acidosis: Does the Accompanying Anion Matter?

Patients with chronic kidney disease (CKD) continue to produce endogenous acids but have a reduction in net acid excretion, resulting in a primary decrease in serum bicarbonate concentration, which is termed chronic metabolic acidosis. Recent prospective studies, along with retrospective cohort analyses, demonstrate a higher risk for CKD progression with untreated metabolic acidosis. To normalize serum bicarbonate levels, acidemic patients are often treated with sodium bicarbonate (NaHCO₃) or sodium citrate, which have been shown to slow the progression of CKD. However, studies using this approach have routinely excluded patients with common sodium-sensitive comorbid conditions, such as poorly controlled hypertension, congestive heart failure, volume overload, or edema. This article examines the effect of the anion that accompanies sodium delivered with these therapies. Do the negative effects on blood pressure (BP) and sodium retention, as measured by an increase in edema, weight gain, and congestive heart failure, observed with oral administration of sodium chloride (NaCl) differ when a similar amount of sodium is given with bicarbonate or citrate in this patient population? A review of the literature suggests that NaHCO₃ does not increase BP or sodium retention when administered to patients with CKD during a concurrent severe NaCl dietary restriction (∼10 mEq/d). However, this degree of NaCl restriction is feasible only under strict control in clinical research environments. In contrast, when NaHCO₃ is given to patients without severe dietary NaCl restriction, there is an increase in BP and sodium retention. Thus, unless patients with CKD can tolerate a diet virtually devoid of NaCl, additional sodium, regardless of the accompanying anion, appears to increase BP and sodium retention.

Wasting in Chronic Kidney Disease – a Complex Issue

Chronic kidney disease (CKD) has become a global health burden and is associated with increased morbidity and mortality. In particular, wasting is highly prevalent in later stages of the illness with muscle loss being a common problem. The aetiology and progression of this wasting is complex and multiple states have been identified linked to wasting in CKD. These include: ‘malnutrition’, ‘disease-related malnutrition’, ‘protein-energy wasting’, ‘cachexia’, ‘sarcopenia’, ‘frailty’ and ‘muscle wasting’. The purpose of this paper is to review these terms in the context of CKD. Common features include weight loss, loss of muscle mass and muscle function principally driven by CKD disease specific factors and inflammatory mediators. Disease-related malnutrition would appear to be a more appropriate term for CKD than malnutrition as it take in to consideration disease specific factors such as inflammation for example.  Frailty is commonly associated with age-related decline in physiological function. Development of novel screening tools measuring across multiple domains of nutritional status, muscle and physical function may be useful in CKD. Research into potential treatments are currently underway with focus on multi-modal therapies including nutrition, resistance training and anabolic drugs such as myostatin blockade and selective androgen receptor modulators. A better understanding of different states and terms may help guide assessment and treatment opportunities for patients.