Metabolic acidosis and malnutrition-inflammation complex syndrome in chronic renal failure

Systemic immune-inflammatory indicators and bone mineral density in chronic kidney disease patients: A cross-sectional research from NHANES 2011 to 2018

BACKGROUND

The purpose of this study was to look at the relationship between the Systemic Immune Inflammatory Index (SII) and bone mineral density (BMD) in the pelvis, left upper and lower limbs, lumbar spine, thoracic spine, and trunk in a chronic kidney disease (CKD) population in the United States.

METHODS

The National Health and Nutrition Examination Survey (2011-2016) yielded 2302 people with CKD aged >18 years. CKD was defined as eGFR less than 90 ml/min/1.73 m2 or eGFR greater than 90 ml/min/1.73 m2 with urine ACR greater than 30 mg/L.SII was calculated as PC * (NC / LC) from platelet count (PC), neutrophil count (NC), and lymphocyte count (LC). Multiple logistic regression was used to examine the relationship between BMD and SII at different sites in CKD patients, smoothed curve-fitting and generalized weighting models were used to investigate non-linear relationships, and a two-tailed linear regression model was used to find potential inflection points in the model.

RESULTS

We discovered a negative correlation between SII and pelvic BMD among 2302 participants after controlling for gender, age, and race [β = -0.008; 95% confidence value -0.008; 95% confidence interval (CI) -0.014, -0.002]. Lower PEBMD was related to increasing SII (trend p = 0.01125). After additional correction, only pelvic BMD remained adversely linked with SII [value -0.006; 95% CI -0.012, -0.000, p = 0.03368]. Smoothed curve fitting revealed a consistent inverse relationship between SII and pelvic BMD. Further stratified analyses revealed a substantial positive negative connection between SII and pelvic BMD in individuals who did not have hypertension, diabetes, a BMI of more than 30 kg/m2, or stage 2 CKD. The connection between SII and PEBMD in people without diabetes revealed a strong inverted U-shaped curve.

CONCLUSION

In individuals with CKD in the United States, there was a negative connection between the systemic immunoinflammatory index (SII) and pelvic BMD. The SII might be a low-cost and simple test for CKD-related BMD loss.

Dietary acid load and markers of malnutrition, inflammation, and oxidative stress in hemodialysis patients

Aims

The present study was conducted to examine the association between dietary acid load (DAL) and markers of inflammation, oxidative stress, and malnutrition in a group of Iranian hemodialysis (HD) patients.

Methods

This cross-sectional study was performed on individuals aged ≥18 years who were on HD at least 6 months before their enrollment in the study. A 4-day dietary recall was used for the evaluation of dietary intake. DAL was calculated using two methods including potential renal acid load (PRAL) and net endogenous acid production (NEAP). For assessing the malnutrition status, we used the subjective global assessment (SGA), dialysis malnutrition score (DMS), and malnutrition inflammation score (MIS). Fasting blood samples were collected from each participant to assess serum levels of high-sensitivity C-reactive protein (hs-CRP), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular adhesion molecule-1 (sVCAM-1), sE-selectin, malondialdehyde (MDA), nitric oxide (NO), and endothelin-1.

Results

In total, 291 patients with a mean age of 57.73 ± 0.88 years and HD vintage of 4.27 ± 0.25 months were enrolled in the current study. Significant positive associations were observed between PRAL and hs-CRP (β = 1.77, 95% CI: 0.88, 2.65), sICAM-1 (β = 83.21, 95% CI: 10.39, 156.04), sVCAM-1 (β = 194.63, 95% CI: 74.68, 314.58), and sE-selectin (β = 6.66, 95% CI: 1.81, 11.50) among participants with the highest PRAL scores, compared to those with the lowest PRAL scores. NEAP was positively correlated with hs-CRP (β = 1.34, 95% CI: 0.46, 2.22), sICAM-1 (β = 88.83, 95% CI: 16.99, 160.67), and MDA (β = 0.35, 95% CI: 0.005, 0.71). Additionally, marginally significant higher odds of SGA (OR = 1.98, 95% CI: 0.95, 4.11) and DMS (OR = 1.94, 95% CI: 0.92, 4.05) were observed in individuals in the third tertile of PRAL vs. the first tertile of PRAL. NEAP had also a marginally significant positive correlation with DMS (OR = 2.01, 95% CI: 0.93, 4.31).

Conclusion

This study illustrates that higher consumption of acidic foods is correlated with markers of inflammation, oxidative stress, and malnutrition in HD patients.

Redox Signaling in Chronic Kidney Disease-Associated Cachexia

Redox signaling alterations contribute to chronic kidney disease (CKD)-associated cachexia. This review aims to summarize studies about redox pathophysiology in CKD-associated cachexia and muscle wasting and to discuss potential therapeutic approaches based on antioxidant and anti-inflammatory molecules to restore redox homeostasis. Enzymatic and non-enzymatic systems of antioxidant molecules have been studied in experimental models of kidney diseases and patients with CKD. Oxidative stress is increased by several factors present in CKD, including uremic toxins, inflammation, and metabolic and hormone alterations, leading to muscle wasting. Rehabilitative nutritional and physical exercises have shown beneficial effects for CKD-associated cachexia. Anti-inflammatory molecules have also been tested in experimental models of CKD. The importance of oxidative stress has been shown by experimental studies in which antioxidant therapies ameliorated CKD and its associated complications in the 5/6 nephrectomy model. Treatment of CKD-associated cachexia is a challenge and further studies are necessary to investigate potential therapies involving antioxidant therapy.

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.

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.

Skeletal Muscle Complications in Chronic Kidney Disease

PURPOSE OF REVIEW

To provide an overview of the recent literature investigating the pathophysiology of skeletal muscle changes, interventions for skeletal muscle, and effects of exercise in chronic kidney disease (CKD).

RECENT FINDINGS

There are multiple CKD-related changes that negatively impact muscle size and function. However, the variability in the assessment of muscle size, in particular, hinders the ability to truly understand the impact it may have in CKD. Exercise interventions to improve muscle size and function demonstrate inconsistent responses that warrant further investigation to optimize exercise prescription. Despite progress in the field, there are many gaps in the knowledge of the pathophysiology of sarcopenia of CKD. Identifying these gaps will help in the design of interventions that can be tested to target muscle loss and its consequences such as impaired mobility, falls, and poor quality of life in patients with CKD.

Impact of Preoperative Handgrip Strength on Postoperative Outcome after Radical Gastrectomy for Gastric Cancer Patients

In this study, we investigated whether preoperative low-handgrip strength (HGS) defined by the Asian working group for sarcopenia could be a predictor of postoperative outcomes in patients with gastric cancer. A total of 327 patients who underwent radical gastrectomy for c-stage I-III primary gastric cancer with pre-operative HGS records were included. The cut-off values of HGS were defined as 28 kg for males and 18 kg for females, with values below and above the cut-off defined as low-HGS and high-HGS, respectively. The primary outcome was infectious complications. We compared the postoperative outcomes of the groups after adjusting for the background using propensity score matching. Of the 327 patients, 246 (75.2%) and 81 (24.8%) were in the high and low-HGS groups, respectively. After adjusting for background, there were 57 patients in both groups. After matching, the low-HGS group had significantly more infectious complications (17.5% vs. 1.8%, p = 0.008). Multivariate analysis of infectious complications in the low-HGS group demonstrated chronic kidney disease and diabetes as independent risk factors (odds ratio 4.390, 95% confidence interval 1.120-17.20, p = 0.034). Preoperative low-HGS according to the Asian criteria was associated with infectious complications after gastrectomy. Chronic kidney disease and diabetes were independent risk factors for infectious complications among patients with low-HGS.

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

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

The Impact of Chronic Kidney Disease on Nutritional Status and Its Possible Relation with Oral Diseases

Several studies have demonstrated a strong relation between periodontal diseases and chronic kidney disease (CKD). The main mechanisms at the base of this link are malnutrition, vitamin dysregulation, especially of B-group vitamins and of C and D vitamins, oxidative stress, metabolic acidosis and low-grade inflammation. In particular, in hemodialysis (HD) adult patients, an impairment of nutritional status has been observed, induced not only by the HD procedures themselves, but also due to numerous CKD-related comorbidities. The alteration of nutritional assessment induces systemic manifestations that have repercussions on oral health, like oral microbiota dysbiosis, slow healing of wounds related to hypovitaminosis C, and an alteration of the supporting bone structures of the oral cavity related to metabolic acidosis and vitamin D deficiency. Low-grade inflammation has been observed to characterize periodontal diseases locally and, in a systemic manner, CKD contributes to the amplification of the pathological process, bidirectionally. Therefore, CKD and oral disease patients should be managed by a multidisciplinary professional team that can evaluate the possible co-presence of these two pathological conditions, that negatively influence each other, and set up therapeutic strategies to treat them. Once these patients have been identified, they should be included in a follow-up program, characterized by periodic checks in order to manage these pathological conditions.

Hyperkalemia and Metabolic Acidosis Occur at a Higher eGFR in Sickle Cell Disease

Background

People with sickle cell disease (SCD) have an elevated estimated glomerular filtration rate (eGFR) compared with the general population, and this may alter the usual creatinine-based eGFR cutoffs for which physiologic evidence of kidney dysfunction is apparent. This study aimed to identify eGFR thresholds for hyperkalemia and metabolic acidosis in patients with SCD.

Methods

This was a cross-sectional analysis of 733 patients with severe (hemoglobin SS or Sβ ⁰-thalassemia) SCD genotype, 238 patients with moderate (hemoglobin SC or Sβ ⁺-thalassemia) SCD genotype, and 1333 age- and sex-matched African Americans from the National Health and Nutrition Examination Survey (NHANES). The prevalence rates of hyperkalemia and metabolic acidosis were compared by eGFR category. Cutoffs for hyperkalemia and metabolic acidosis were determined using generalized additive models.

Results

Hyperkalemia and metabolic acidosis were more common in those with severe SCD genotype (13% and 21%, respectively) compared with the NHANES (0.3% and 5%, respectively); the prevalence rates in the moderate SCD genotype were intermediate for hyperkalemia (3%) and metabolic acidosis (11%). The proportion of patients with hyperkalemia and metabolic acidosis progressively increased with lower eGFR category in both SCD genotype groups. The eGFR thresholds for hyperkalemia and metabolic acidosis were higher in the severe (85 and 91 ml/min per 1.73 m², respectively) and moderate (52 and 102 ml/min per 1.73 m², respectively) SCD genotypes compared with the NHANES (34 and 46 ml/min per 1.73 m²).

Conclusions

We demonstrate that hyperkalemia and metabolic acidosis are more common and occur at higher eGFR values in patients with SCD compared with age- and sex-matched African Americans, including in eGFR ranges considered to be normal. Future studies using redefined creatinine-based eGFR thresholds for abnormal kidney function may identify high-risk patients for earlier intervention strategies and referral for specialized renal care in SCD.

Effects of Oral Bicarbonate Supplementation on the Cardiovascular Risk Factors and Serum Nutritional Markers in Non-Dialysed Chronic Kidney Disease Patients

Background and Objectives: Kidneys play a key role in maintaining the acid−base balance. The aim of this study was to evaluate the effect of a 3-month oral sodium bicarbonate administration on arterial wall stiffness, arterial pressure and serum nutritional markers in non-dialysed patients with chronic kidney disease (CKD) stages 3−5 and metabolic acidosis. Methods: Eighteen CKD patients with eGFR < 45 mL/min/1.73 m2 and capillary blood bicarbonate (HCO3) < 22 mmol/L were enrolled in this single-centre, prospective study. Anthropometric parameters, pulse wave velocity, 24-h ambulatory blood pressure measurements, blood and urine parameters were assessed at the beginning and at the end of the study. The patients received supplementation with 2 g of sodium bicarbonate daily for three months. Results: A significant increase of pH: 7.32 ± 0.06 to 7.36 ± 0.06; p = 0.025, HCO3 from 18.7 mmol/L (17.7−21.3) to 22.2 mmol/L (20.2−23.9); p < 0.001 and a decrease in base excess from −6.0 ± 2.4 to −1.9 ± 3.1 mmol/L; p < 0.001 were found. An increase in serum total protein from 62.7 ± 6.9 to 65.8 ± 6.2; p < 0.013 and albumin from 37.3 ± 5.4 to 39.4 ± 4.8; p < 0.037 but, also, NT-pro-BNP (N-Terminal Pro-B-Type Natriuretic Peptide) from 794.7 (291.2−1819.0) to 1247.10 (384.7−4545.0); p < 0.006, CRP(C Reactive Protein) from 1.3 (0.7−2.9) to 2.8 (1.1−3.1); p < 0.025 and PTH (parathyroid hormone) from 21.5 ± 13.7 to 27.01 ± 16.3; p < 0.006 were observed, as well as an increase in erythrocyte count from 3.4 ± 0.6 to 3.6 ± 0.6; p < 0.004, haemoglobin from 10.2 ± 2.0 to 11.00 ± 1.7; p < 0.006 and haematocrit from 31.6 ± 6.00 to 33.6 ± 4.8; p < 0.009. The mean eGFR during sodium bicarbonate administration did not change significantly: There were no significant differences in pulse wave velocity or in the systolic and diastolic BP values. Conclusion: The administration of sodium bicarbonate in non-dialysed CKD patients in stages 3−5 improves the parameters of metabolic acidosis and serum nutritional markers; however, it does not affect the blood pressure and vascular stiffness.

Estimated Glomerular Filtration Rate in Chronic Kidney Disease: A Critical Review of Estimate-Based Predictions of Individual Outcomes in Kidney Disease

Chronic kidney disease (CKD) is generally regarded as a final common pathway of several renal diseases, often leading to end-stage kidney disease (ESKD) and a need for renal replacement therapy. Estimated GFR (eGFR) has been used to predict this outcome recognizing its robust association with renal disease progression and the eventual need for dialysis in large, mainly cross-sectional epidemiological studies. However, GFR is implicitly limited as follows: (1) GFR reflects only one of the many physiological functions of the kidney; (2) it is dependent on several non-renal factors; (3) it has intrinsic variability that is a function of dietary intake, fluid and cardiovascular status, and blood pressure especially with impaired autoregulation or medication use; (4) it has been shown to change with age with a unique non-linear pattern; and (5) eGFR may not correlate with GFR in certain conditions and disease states. Yet, many clinicians, especially our non-nephrologist colleagues, tend to regard eGFR obtained from a simple laboratory test as both a valid reflection of renal function and a reliable diagnostic tool in establishing the diagnosis of CKD. What is the validity of these beliefs? This review will critically reassess the limitations of such single-focused attention, with a particular focus on inter-individual variability. What does science actually tell us about the usefulness of eGFR in diagnosing CKD?

Effects of AST-120 on muscle health and quality of life in chronic kidney disease patients: results of RECOVERY study

BACKGROUND

The prevalence of sarcopenia is increased with declining renal function. Elevated serum indoxyl sulfate levels are associated with poor skeletal muscle conditions. We aimed to determine the effects of AST-120, the oral adsorbent of indoxyl sulfate, on sarcopenia and sarcopenia-associated factors in chronic kidney disease patients.

METHODS

This was a 48 week, randomized controlled, parallel group, open-label, multicentre trial (n = 150). The participants were randomly assigned in a 1:1 ratio to the control (CON) and AST-120 (Renamezin®, REN) groups. Outcome measurements were performed at baseline and every 24 weeks for 48 weeks. The primary outcome was gait speed difference ≥0.1 m/s between the two groups, and secondary outcomes included hand grip strength, muscle mass, and health-related quality of life.

RESULTS

A difference of gait speed ≥0.1 m/s was not observed during the study period. The mean dynamic-start gait speed in the REN group increased from baseline to 48 weeks (1.04 ± 0.31 to 1.08 ± 0.32 m/s, P = 0.019). The static-start gait speed changed by -0.024 and 0.04 m/s (P = 0.049) in the CON and REN groups over 48 weeks, respectively. Hand grip strength decreased during the first 24 weeks and did not significantly change over the next 24 weeks in either group. The proportion of low muscle mass or sarcopenia at baseline was larger in the REN group than in the CON group, but the difference attenuated over the study period [low muscle mass and sarcopenia in the CON and REN groups at baseline, 4.0% vs. 18.9% (P = 0.004) and 2.7% vs. 13.5% (P = 0.017); at 24 weeks, 2.9% vs. 13.6% (P = 0.021) and 1.4% vs. 10.5% (P = 0.029); and at 48 weeks, 7.6% vs. 12.9% (P = 0.319) and 4.5% vs. 8.1% (P = 0.482), respectively]. Bodily pain, vitality, symptoms/problems, and cognitive function in the REN group improved, while the quality of social interactions and the kidney disease effects in the CON group aggravated from baseline to 48 weeks. Interaction between time and group was evident only in symptoms/problems, cognitive function, and kidney disease effects.

CONCLUSIONS

The addition of AST-120 to standard treatment in chronic kidney disease patients did not make a significant difference in gait speed, although AST-120 modestly had beneficial effects on gait speed change and quality of life and showed the potential to improve sarcopenia. (clinicaltrials.gov: NCT03788252).

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.

Plant-Based versus Animal-Based Low Protein Diets in the Management of Chronic Kidney Disease

Recent data reiterate low-protein diets (LPDs) as cornerstones in the conservative management of chronic kidney disease (CKD). The reduction in proteinuria, better blood pressure control and the reduction in the rate of decline in kidney function with LPDs were reported, both in non-diabetics and diabetics patients. Supplemented, vegetarian, very-low-protein diets (sVLPD, 0.3 g/kg-day) could postpone kidney replacement therapy (KRT) initiation, mainly through the better control of metabolic disorders of advanced CKD in non-diabetic patients. Plant-based diets could ameliorate gut microbiota and appear to be superior to mixed hypoproteic diets in treating advanced CKD: better control of nitrogen balance, acid-base metabolism and bone mineral disorders. Vegetarian diets generate fewer uremic toxins and reduce salt intake and acid overload. At the same time, they can improve lipid metabolism, providing a high ratio of unsaturated to saturated fatty acids, as well as insulin resistance.

Chronic Kidney Disease: Strategies to Retard Progression

Chronic kidney disease (CKD), defined as the presence of irreversible structural or functional kidney damages, increases the risk of poor outcomes due to its association with multiple complications, including altered mineral metabolism, anemia, metabolic acidosis, and increased cardiovascular events. The mainstay of treatments for CKD lies in the prevention of the development and progression of CKD as well as its complications. Due to the heterogeneous origins and the uncertainty in the pathogenesis of CKD, efficacious therapies for CKD remain challenging. In this review, we focus on the following four themes: first, a summary of the known factors that contribute to CKD development and progression, with an emphasis on avoiding acute kidney injury (AKI); second, an etiology-based treatment strategy for retarding CKD, including the approaches for the common and under-recognized ones; and third, the recommended approaches for ameliorating CKD complications, and the final section discusses the novel agents for counteracting CKD progression.

Yi-Qi-Jian-Pi-Xiao-Yu-Xie-Zhuo Formula Improves Muscle Atrophy via Modulating the IGF-1/PI3K/Akt Signaling Pathway in 5/6 Nephrectomized Rats

The Yi–Qi–Jian–Pi–Xiao–Yu–Xie–Zhuo (YQJPXYXZ) formula has been used for treating chronic kidney disease (CKD) for many years with good efficiency based on the cumulative empirical experience of previous practitioners. Impairment of the IGF-1/PI3K/Akt signaling pathway plays an important role in mediating muscle wasting. This study aimed to observe effects of the YQJPXYXZ formula on muscle atrophy in CKD rats and investigate its possible mechanism on regulation of the IGF-1/PI3K/Akt signaling pathway. The 5/6 nephrectomized rats were randomly allocated into 3 groups: the CKD group, the KT (compound α-ketoacid tablets) group, and the YQJPXYXZ group. Besides, sham-operated rats were included as the sham group. All rats were treated for 12 weeks. Results showed that administration of the YQJPXYXZ formula prevented body weight loss and muscle fiber size decrease. Moreover, the YQJPXYXZ formula increased the IGF-1 level of serum and skeletal muscle in CKD rats and enhanced the phosphorylation level of Akt. Furthermore, the YQJPXYXZ formula decreased the Atrogin1 and MuRF1 mRNA and MuRF1 proteins. In conclusion, our data demonstrated that the YQJPXYXZ formula improves muscle wasting in CKD rats, which might be associated with the modulation of the IGF-1/PI3K/Akt signaling pathway and inhibition of the ubiquitin–proteasome system (UPS).

Nutritional Management for Dogs and Cats with Chronic Kidney Disease

The nutritional management of canine and feline chronic kidney disease and protein-losing nephropathy is discussed. Special attention is paid to assessment of body composition (body weight, body condition score, and muscle condition score) and the dysrexia that often occurs with kidney disease. Various nutrients of concern are discussed and specific dietary options are provided.

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.

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.

Chronic Metabolic Acidosis Elicits Hypertension via Upregulation of Intrarenal Angiotensin II and Induction of Oxidative Stress

Chronic metabolic acidosis (CMA) can be a consequence of persistent hypertension but could potentially play a role in invoking hypertension. Currently, there is a scarcity of studies examining the outcome of induced chronic acidosis on blood pressure regulation. This study investigates CMA as a cause of hypertension. Chronic acidosis was induced in Sprague Dawley rats (100–150 g) by providing a weak acid solution of 0.28 M ammonium chloride (NH₄Cl) in tap water for 8 weeks. To determine whether the rats were acidotic, blood pH was measured, while blood pressure (BP) was monitored by tail-cuff plethysmography weekly. Rats were divided into five groups: control, CMA, CMA ± spironolactone, captopril, and tempol. Serum sodium and potassium; renal interstitial fluid (for Angiotensin II concentration); and kidney proximal tubules (for Na⁺/K⁺ ATPase- α1 concentration) were analyzed. Reactive oxygen species (ROS) were detected in renal cortical homogenates using electron paramagnetic resonance (EPR). In the CMA rats, a sustained elevation in mean arterial pressure (MAP) associated with a significant decrease in blood pH was observed compared to that of control over the 8 weeks. A significant decrease in MAP was observed in acidotic rats treated with captopril/tempol, whereas spironolactone treatment caused no decrease in MAP as compared to that of the CMA group. The interstitial angiotensin II was increased in the CMA group but decreased in the CMA with captopril and tempol groups. In addition, the urinary sodium was decreased, and the serum sodium levels increased significantly in the CMA groups as compared to that of control. However, the acidotic groups with captopril and tempol showed reduced levels of serum sodium and an elevation in urinary sodium as compared to that of the CMA group. In addition, there was a significant increase in plasma renin and no change in plasma aldosterone in the CMA group with no significant differences in plasma renin or aldosterone observed during spironolactone, captopril, or tempol treatments. The increased expression of Na⁺/K⁺ ATPase-α1 in the CMA group suggests that active transport of Na⁺ to the blood could be causative of the observed hypertension. Furthermore, the EPR analysis confirmed an elevation in superoxide (O₂^-) radical levels in the CMA group, but the tempol/captopril treated acidotic groups showed less (O₂^-) compared to that of either the CMA group or control. Taken together, our data suggest that induction of CMA could potentially be causative of hypertension, while the mechanisms underlying the increased BP could be through the activation of intrarenal Ang II and induction of oxidative stress.

Is Metabolic Acidosis a Novel Risk Factor for a Long-Term Graft Survival in Patients after Kidney Transplantation?

BACKGROUND

Results of both experimental and clinical studies suggest that metabolic acidosis (MA) contributes to the progression of chronic kidney disease (CKD) and mortality in CKD patients. It is unknown whether the same relationship exists in kidney transplantation (KTx) patients. The aim of this observational study was to examine this relationship between MA and both mortality and renal outcomes in patients after KTx.

METHODS

Four hundred eighty-six (290 male; 196 female) patients aged 48 ± 12 years, at least 1 year after KTx, were analyzed. Blood HCO3- was measured, and patients were then observed over 3 years. MA was defined as the blood HCO3- concentration <22 mmol/L. The end points of survival analysis were death and initiation of dialysis therapy. In patients who did not reach the above-mentioned end points, the difference between final (after 3 years of follow-up) and initial estimated glomerular filtration rate (eGFR) was calculated.

RESULTS

MA was initially diagnosed in 57 (12%) patients after KTx. Three-year patient survival was 89.5% in the MA group and 97.4% in the non-MA group (p = 0.001). Three-year graft survival was 73.7% for patients with MA and 93.0% for patients without MA (p < 0.001). In patients with MA who did not reach study end points, blood bicarbonate concentration at baseline correlated positively with a change in eGFR (R = 0.48, p = 0.002, n = 36). Such a correlation was not found in patients without MA (n = 388).

CONCLUSIONS

(1) MA significantly increases the risk of mortality in patients after KTx. (2) The intensity of MA may be associated with progression of transplanted kidney dysfunction in KTx patients.

Effect of high bicarbonate hemodialysis solution on biochemical parameters and anthropometric indices

INTRODUCTION

Protein energy wasting is an adverse consequence of renal failure, which is correlated with increased mortality and morbidity. Metabolic acidosis has a major role in the development of protein energy wasting in hemodialysis patients. Every effort that could ameliorate this catabolic state would be beneficial to stabilize body composition. The aim of this study was to investigate the possible beneficial effects of high bicarbonate dialysis on anthropometric indices and biochemical parameters of nutrition.

METHODS

Fifty-six hemodialysis patients were randomly enrolled in two groups: an intervention group that underwent hemodialysis for 6 months with high bicarbonate dialysate concentration (36 mmol/L, N = 26) and a control group that underwent hemodialysis using a bicarbonate dialysate concentration of 30 mmol/L (N = 30). Biochemical parameters of nutrition and weight, body mass index (BMI), total body water, percent body fat, and other anthropometric indices were measured at the beginning and the end of the trial.

FINDINGS

At the end of the 6 month evaluation period, plasma levels of albumin, phosphorus, K, calcium, and bicarbonate showed no significant changes. Body weight and BMI increased significantly in high bicarbonate arm but did not change significantly in the control group. Percent body fat in the arms and legs did not change in intervention arm, but decreased significantly in the controls.

DISCUSSION

The results suggest that higher bicarbonate dialysis can have beneficial effects on nutritional status and might protect against loss of fat mass.

Immune system stimulation increases the irreversible loss of cysteine to taurine, but not sulfate, in starter pigs

An isotope tracer study was conducted to evaluate the effects of immune system stimulation (ISS) on the irreversible loss of cysteine (Cys) to taurine (Tau) and sulfate (SO4), as well as glutathione (GSH) synthesis, during the fed state in pigs. We previously have reported that ISS increases plasma Cys flux and the GSH synthesis rate at the tissue and whole-body levels in growing pigs. Thus, the current article presents the data on the irreversible loss of Cys during ISS in pigs. Ten gilts (BW: 7.0 ± 0.12 kg) were feed restricted a sulfur amino acids (SAA) limiting diet and injected twice with either saline (n = 4) or increasing amounts of E. coli lipopolysaccharide (n = 6). The day after the second injection, a 5-h primed continuous intravenous infusion of 35S-Cys was conducted. ISS reduced plasma Cys and total SAA concentrations (16% and 21%, respectively; P < 0.05). However, ISS had no effect on the plasma concentrations of Tau and SO4, nor did it affect the appearance of 35S in plasma Tau, plasma SO4, urinary Tau, or urinary SO4 (P > 0.19). On a whole-body basis and including urinary excretion, ISS increased the appearance of 35S in Tau by 67% (P < 0.05), but tended to decrease the appearance of 35S in SO4 by 22% (P < 0.09). Overall, the current findings indicate that during ISS, decreased plasma SAA concentrations and increased plasma Cys flux are attributed in part to increased rates of Cys conversion to Tau, but not Cys catabolism to SO4. Thus, increased utilization of Cys for the synthesis of immune system metabolites, such as GSH and Tau, is likely the main contributor to increased Cys flux during ISS in pigs. In addition, the irreversible loss of Cys during ISS is small and has a minimal impact on the daily SAA requirements of starter pigs.

A Study on Effect of Bicarbonate Supplementation on the Progression of Chronic Kidney Disease

Introduction:

Chronic kidney disease (CKD) is a major health problem in India. Prevalence of CKD will continue to rise, reflecting the growing elderly population and increasing number of patients with diabetes and hypertension.

Methods:

A total of 67 patients with CKD participated in the study. Patients were randomized into two groups. Group 1 received oral bicarbonate and Group 2 was the control group. Their baseline, 6 and 9 months estimated glomerular filtration rate (eGFR), bicarbonate, muscle mass and serum albumin were estimated. We analysed the effect of bicarbonate supplementation on the progression of CKD.

Results:

Bicarbonate supplementation decreased the metabolic acidosis in CKD patients. After bicarbonate supplementation, the serum bicarbonate level increased time-dependently from 16.62 to 18.02 and 19.77 mEq/L after 6 and 9 months, respectively. It also restored the eGFR to its baseline value. The eGFR values of Group 1 at baseline, after 6 months and 9 months were 22.39, 22.66, and 22.65 mL/min/1.73 m2, respectively. In contrast, the eGFR value in Group 2 reduced significantly. Patients who received bicarbonate supplementation displayed increased serum albumin levels compared with the controls. The albumin level was significantly increased from 4.05 to 4.24 and 4.34 g/dL, respectively, after 6 and 9 months (P = 0.0001). Also, bicarbonate supplementation showed significant improvement in muscle mass.

Conclusion:

Study confirms the role of bicarbonate in relieving the metabolic acidosis and thereby its possible role in the management of CKD progression.

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.

Factors related to peripheral arterial disease in patients undergoing hemodialysis: the potential role of monocyte chemoattractant protein-1

Peripheral arterial disease (PAD) is substantially prevalent among patients in the end stage of renal disease (ESRD). We considered factors related to peripheral arterial disease in patients undergoing hemodialysis including the important role of monocyte chemoattractant protein-1 (MCP-1) serum concentrations. We studied 150 patients in on-line-predilution hemodiafiltration. Dialysis sufficiency was defined by Kt/V for urea. PAD was defined using clinical criteria, ankle-brachial index and Doppler ultrasound in the lower limbs. MCP-1 serum concentrations were measured using enzyme-linked immunoabsorbed assay (ΕLISA). We performed chi-square tests and logistic regression analysis to investigate risk factors for the prevalence of PAD in these patients including MCP-1 serum concentrations. The patients with manifested PAD had elevated MCP-1, higher BP, higher arterial stiffness markers, higher markers of malnutrition, uncontrolled metabolic acidosis, bone disease and lower obtained dialysis adequacy than the patients without PAD. The association between PAD manifestation and high MCP-1 was found significant (x² = 9.6, p = 0.001). The built logistic regression analysis showed that the high MCP-1 increased the risk for PAD 3.2 (95% C.I 1.3-8.2) folds after adjustment for confounders. PAD was also significantly associated with non-administration of vitamin D agents during dialysis (x² = 3.5, p = 0.04).Malnutrition, low-grade inflammation mainly defined by high MCP-1 serum concentrations, metabolic acidosis and bone disease were included in significant predictors for peripheral arterial disease in patients undergoing hemodiafiltration. The obtained dialysis sufficiency and the therapy during dialysis sessions seem to play an additional role in the demonstration of peripheral vascular disease in these patients.

Metformin: Mechanisms in Human Obesity and Weight Loss

PURPOSE OF REVIEW

Metformin has multiple benefits for health beyond its anti-hyperglycemic properties. The purpose of this manuscript is to review the mechanisms that underlie metformin's effects on obesity.

RECENT FINDINGS

Metformin is a first-line therapy for type 2 diabetes. Large cohort studies have shown weight loss benefits associated with metformin therapy. Metabolic consequences were traditionally thought to underlie this effect, including reduction in hepatic gluconeogenesis and reduction in insulin production. Emerging evidence suggests that metformin-associated weight loss is due to modulation of hypothalamic appetite regulatory centers, alteration in the gut microbiome, and reversal of consequences of aging. Metformin is also being explored in the management of obesity's sequelae such as hepatic steatosis, obstructive sleep apnea, and osteoarthritis. Multiple mechanisms underlie the weight loss-inducing and health-promoting effects of metformin. Further exploration of these pathways may be important in identifying new pharmacologic targets for obesity and other aging-associated metabolic diseases.

Oral Sodium Bicarbonate Supplementation Does Not Affect Serum Calcification Propensity in Patients with Chronic Kidney Disease and Chronic Metabolic Acidosis

BACKGROUND

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD) and metabolic acidosis might accelerate vascular calcification. The T50 calcification inhibition test (T50-test) is a global functional test analyzing the overall propensity of calcification in serum, and low T50-time is associated with progressive aortic stiffening and with all-cause mortality in non-dialysis CKD, dialysis, and transplant patients. Low serum bicarbonate is associated with a short T50-time and alkali supplementation could be a simple modifier of calcification propensity. The aim of this study was to investigate the short-term effect of oral sodium bicarbonate supplementation on T50-time in CKD patients.

MATERIAL AND METHODS

The SoBic-study is an ongoing randomized-controlled trial in CKD-G3 and G4 patients with chronic metabolic acidosis (serum HCO3- ≤21 mmol/L), in which patients are randomized to either achieve serum HCO3- levels of 24 ± 1 mmol/L (intervention group) or 20 ± 1 mmol/L (rescue group). The effect of bicarbonate treatment on T50-time was assessed.

RESULTS

The study cohort consisted of 35 (14 female) patients aged 57 (±15) years, and 18 were randomized to the intervention group. The mean T50-time was 275 (± 64) min. After 4 weeks, the mean change of T50-time was 4 (±69) min in the intervention group and 18 min (±56) in the rescue group (β = -25; 95% CI: -71 to 22; p = 0.298). Moreover, change of serum bicarbonate in individual patients was not associated with change in T50-time, analyzed by regression analysis. Change of serum phosphate had a significant impact on change of T50-time (β = -145; 95% CI: -237 to -52).

CONCLUSION

Oral sodium bicarbonate supplementation showed no effect on T50-time in acidotic CKD patients.

Oral Bicarbonate Therapy in Non-Haemodialysis Dependent Chronic Kidney Disease Patients: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Metabolic acidosis is a common complication in chronic kidney disease (CKD) patients, and is associated with an accelerated decline in renal function. Oral bicarbonate therapy has been used to counteract metabolic acidosis in CKD for decades. However, until recently, there have been very few intervention studies testing the effectiveness of bicarbonate therapy at improving metabolic acidosis or its consequences in patients with CKD. In this systematic review and meta-analysis, we aimed to examine the outcomes of all published randomised controlled trials (RCTs) that investigated the effect of oral bicarbonate therapy in adults with CKD. Ovid MEDLINE^®, EMBASE^® and Cochrane Library were searched in mid-October 2018 for English literature, with no restrictions applied to the publication status or date. Seven RCTs that recruited 815 participants met our inclusion criteria after full text review. Oral bicarbonate supplementation resulted in a slightly higher estimated glomerular filtration rate (eGFR) (mean difference 3.1 mL/min per 1.73 m²; 95% CI 1.3–4.9) and serum bicarbonate levels (mean difference 3.4 mmol/L; 95% CI 1.9–4.9) at the end of follow-up (three months to five years) compared to those given placebo or conventional CKD treatment. When limited to studies reporting outcomes at one year, the positive effect of oral bicarbonate therapy on eGFR was attenuated. There were no significant treatment effects in other parameters such as systolic blood pressure (BP) and weight. These findings should be interpreted with caution and further trial evidence is needed to establish the net overall benefit or harm of oral bicarbonate therapy in CKD.

The impact of a nutritional intervention based on egg white for phosphorus control in hemodialyis patients

BACKGROUND AND AIMS

Here we describe a dietary intervention for hyperphosphatemia in dialysis patients based on the partial replacement of meat and fish, which are one of the main sources of alimentary phosphorous, with egg white, a virtually phosphorous-free protein source. This intervention aims to reduce phosphorous intake without causing protein wasting.

PATIENTS AND METHODS

As many as 23 hyperphosphatemic patients (15 male and 8 female, mean age 53.0 ± 10.0 years) on chronic standard 4 h, three times weekly, bicarbonate hemodialysis were enrolled in this open-label, randomized controlled trial. Patients in the intervention group were instructed to replace fish or meat with egg white in three meals a week for three months whereas diet was unchanged in the control group.

RESULTS

Serum phosphate concentrations were significantly lower in the intervention group than in controls after three (4.9 ± 1.0 vs 6.6 ± 0.8; p < 0.001) but not after one month of treatment. Phosphate concentrations decreased more from baseline in the intervention than in the control group both after one (-1,2 ± 1,1 vs 0,5 ± 1,1; p = 0.004) and after three (-1,7 ± 1,1 vs -0,6 ± 1,1; p < 0.001) months of follow-up. No change either in body weight or in body composition assessed with bioelectrical impedance analysis or in serum albumin concentration was observed in either group.

CONCLUSION

The partial replacement of meat and fish with egg white induces a significant decrease in serum phosphate without causing protein malnutrition and could represent a useful instrument to control serum phosphate levels in hemodialysis patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT03236701.

Emerging role of myostatin and its inhibition in the setting of chronic kidney disease

The past two decades have witnessed tremendous progress in our understanding of the mechanisms underlying wasting and cachexia in chronic kidney disease (CKD) and in other chronic illnesses, such as cancer and heart failure. In all these conditions wasting is an effect of the activation of protein degradation in muscle, a response that increases the risk of morbidity and mortality. Major recent advances in our knowledge on how CKD and inflammation affect cellular signaling include the identification of the myostatin (MSTN)/activin system, and its related transcriptional program that promotes protein degradation. In addition, the identification of the role of MSTN/activin in the vascular wall shows premise that its inhibition can better control or prevent some effects of CKD on vessels, such as accelerated atherosclerosis and vascular calcifications. In this review, we summarize the expanding role of MSTN activation in promoting muscle atrophy and the recent clinical studies that investigated the efficacy of MSTN/activin pathway antagonism in sarcopenic patients. Moreover, we also review the utility of MSTN inhibition in the experimental models of CKD and its potential advantages in CKD patients. Lessons learned from clinical studies on MSTN antagonism in sarcopenic patients tell us that the anabolic intervention is likely better if we use a block of the two ActRII receptors. At the same time, however, it is becoming clear that MSTN-targeted therapies should not be seen as a substitute for physical activity and nutritional supplementation which are mandatory to successfully manage patients with wasting.

Prognostic factor determination mortality of acute glufosinate-poisoned patients

Background:

Glufosinate-containing herbicide is increasingly used in agriculture. Its poisoning is a worldwide concern. More and more patients are poisoned by glufosinate. The aim of this study was to determine the factors associated with mortality of patients with acute poisoning of glufosinate.

Methods:

This was a retrospective cohort study conducted from January 1998 to October 2015. Using a multivariate logistic analysis, data for the total population were retrospectively analyzed to determine the factors associated with mortality. Various variables were compared in survivors and non-survivors. Significant predictive variables, Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system, the Simplified Acute Physiology Score (SAPS) II, and Sequential Organ Failure Assessment (SOFA) score were compared by analyzing receiver operating characteristic (ROC) curves.

Results:

A total of 253 patients (mean age: 58 years) were enrolled. Of the 253 patients, 219 (86.6%) survived and 34 (13.4%) died. Decreased Glasgow Coma Scale (GCS) and bicarbonate (HCO3−), use of mechanical ventilator, and use of vasopressors (dopamine, dobutamine, norepinephrine) were associated with mortality. The areas under the curve in the ROC curve analysis for the predictive variables, SOFA score, APACHE II scoring system, and SAPS II were 0.952, 0.829, 0.927, and 0.944, respectively.

Conclusion:

Four predictive variables (GCS < 9, HCO3− < 16.0 mmol/L, mechanical ventilator apply, and use of vasopressors) were associated with mortality in the total population of patients with acute poisoning of glufosinate. These predictive variables had good discriminative power for predicting mortality of patients with acute poisoning of glufosinate-containing herbicide compared to APACHE II, SOFA, and SAPS II.

The Association between Intradialytic Hypertension and Metabolic Disorders in End Stage Renal Disease

Background

Intradialytic hypertension was associated with a high mortality risk. We examined the relationship between intradialytic hypertension and metabolic disorders in hemodialysis treatment patients.

Methods

We studied 76 patients in online hemodiafiltration. Dialysis adequacy was defined by Kt/V for urea. Normalized protein catabolic rate (nPCR), as a marker of protein intake, was calculated. Sodium removal was determined as percent sodium removal. Metabolic acidosis was determined by serum bicarbonate less than 22 mmol/L. Interdialytic urine volume more than 100 ml was recorded. Intradialytic hypertension was defined by an increase in systolic blood pressure equal to 10 mmHg from pre- to posthemodialysis. Arterial stiffness was assessed as carotid-femoral pulse wave velocity (c-fPWV) and carotid augmentation index (AIx). Chi-square tests and logistic regression analysis were applied for intradialytic hypertension prediction.

Results

Patients with intradialytic hypertension were older and had significantly lower hemoglobin, nPCR, urine output, and serum bicarbonate and significantly higher c-fPWV, though similar Kt/V for urea, than patients without intradialytic hypertension. They also had increased sodium removal and pulse pressure related to less urine output. Serum bicarbonate was inversely associated with c-fPWV (r = -0.377, p = 0.001). Chi-square test showed significant association between intradialytic hypertension and serum bicarbonate < 22 mmol/L (x² = 5.6, p = 0.01), which was supported by an adjusted model.

Conclusion

The intradialytic hypertension was significantly associated with metabolic disorders including malnutrition/inflammation and uncontrolled metabolic acidosis in hemodialysis treatment patients. Severe metabolic acidosis may reflect sodium imbalance and hemodynamic instability of these patients resulting in volume overload and increased vascular resistance.

Effects of aging and comorbidities on nutritional status and muscle dysfunction in patients with COPD

Chronic obstructive pulmonary disease (COPD) is a prevalent, complex and debilitating disease which imposes a formidable burden on patients and the healthcare system. The recognition that COPD is a multifaceted disease is not new, and increasing evidence have outlined the importance of its extra-pulmonary manifestations and its relation to other comorbid conditions in the clinical course of the disease and its societal cost. The relationship between aging, COPD and its comorbidities on skeletal muscle function and nutritional status is complex, multidirectional and incompletely understood. Despite this, the current body of knowledge allows the identification of various, seemingly partially independent factors related both to the normal aging process and to the independent deleterious effects of chronic diseases on muscle function and body composition. There is a dire need of studies evaluating the relative contribution of each of these factors, and their potential synergistic effects in patients with COPD and advanced age/comorbid conditions, in order to delineate the best course of therapeutic action in this increasingly prevalent population.

Mortality and Low Serum Bicarbonate Level in Patients on Hemodiafiltration versus Peritoneal Dialysis

Mortality is substantially elevated in patients on chronic kidney disease in comparison to general population. In this study, we observed the mortality rate in relation to risk factors including low serum bicarbonate level, coronary artery disease (CAD), and dialysis modality in patients on dialysis during a median follow-up time of 60 months. We studied 96 dialysis patients, 62 males and 34 females, on mean age 62.1 ± 14.27 years old. The treatment modalities which were applied were predilution hemodiafiltration (HDF, n = 76), and peritoneal dialysis (PD, n = 20). We performed Kaplan-Meier curves and a Cox-regression analysis to investigate significant risk factors for mortality including hypertension, diabetes mellitus, smoking, bone disease defined by intact-parathormone, serum albumin, serum bicarbonate levels < or >22 mEq/L, dialysis modality, and the existence of CAD. Cox-regression analysis revealed a significant impact of serum bicarbonate levels <22 mEq/L on mortality in combination to dialysis modality and CAD. The prevalence of CAD on mortality was found significant (log-rank = 5.507, P = 0.02). Furthermore, the impact of dialysis modality on mortality was shown significant (log rank = 22.4, P = 0.001), noting that during the first 28-30 months from the treatment initiation, the survival was better for PD; but then, the mortality was significantly increased comparatively to HDF. Uncorrected metabolic acidosis and CAD were shown as independent significant predictors for mortality in patients on renal replacement therapy. PD may provide worse survival after 2-2.5 years of treatment initiation than HDF.

The Association between Intradialytic Hypertension and Metabolic Disorders in End Stage Renal Disease

BACKGROUND

Intradialytic hypertension was associated with a high mortality risk. We examined the relationship between intradialytic hypertension and metabolic disorders in hemodialysis treatment patients.

METHODS

We studied 76 patients in online hemodiafiltration. Dialysis adequacy was defined by Kt/V for urea. Normalized protein catabolic rate (nPCR), as a marker of protein intake, was calculated. Sodium removal was determined as percent sodium removal. Metabolic acidosis was determined by serum bicarbonate less than 22 mmol/L. Interdialytic urine volume more than 100 ml was recorded. Intradialytic hypertension was defined by an increase in systolic blood pressure equal to 10 mmHg from pre- to posthemodialysis. Arterial stiffness was assessed as carotid-femoral pulse wave velocity (c-fPWV) and carotid augmentation index (AIx). Chi-square tests and logistic regression analysis were applied for intradialytic hypertension prediction.

RESULTS

Patients with intradialytic hypertension were older and had significantly lower hemoglobin, nPCR, urine output, and serum bicarbonate and significantly higher c-fPWV, though similar Kt/V for urea, than patients without intradialytic hypertension. They also had increased sodium removal and pulse pressure related to less urine output. Serum bicarbonate was inversely associated with c-fPWV (r = -0.377, p = 0.001). Chi-square test showed significant association between intradialytic hypertension and serum bicarbonate < 22 mmol/L (x² = 5.6, p = 0.01), which was supported by an adjusted model.

CONCLUSION

The intradialytic hypertension was significantly associated with metabolic disorders including malnutrition/inflammation and uncontrolled metabolic acidosis in hemodialysis treatment patients. Severe metabolic acidosis may reflect sodium imbalance and hemodynamic instability of these patients resulting in volume overload and increased vascular resistance.

Alkaline Diet and Metabolic Acidosis: Practical Approaches to the Nutritional Management of Chronic Kidney Disease

The kidneys play an extremely important role in maintaining the body acid-base balance by excreting nonvolatile acids and regenerating and reabsorbing bicarbonate in the kidney tubules. As the individual loses their kidney function, renal excretion of nonvolatile acid produced by metabolism of the diet is impaired, resulting in low-grade metabolic acidosis. With this in mind, it is relevant to better understand the dietary aspects related to the acid-base balance in chronic kidney disease metabolic acidosis and try to provide possible strategies for the nutritional management of these cases. The type of diet can deeply affect the body by providing acid or base precursors. Generally speaking, foods such as meat, eggs, cheese, and grains increase the production of acid in the organism, whereas fruit and vegetables are alkalizing. On the other hand, milk is considered neutral as well as fats and sugars, which have a small effect on acid-base balance. The modern Western-type diet is deficient in fruits and vegetables and contains excessive animal products. Thus metabolic acidosis may be exacerbated by a contemporary Western diet, which delivers a high nonvolatile acid load. The remaining acid is neutralized or stored within the body. Bone and muscle are lost to neutralize the acid and serum bicarbonate falls. Early studies suggest that lowering the dietary acid load with a reduced protein content and vegetable proteins replacements, associated with an increase in fruits and vegetables intake can improve the metabolic parameters of acidosis, preserve bone and muscle, and slow the glomerular filtration rate decline. More studies focusing on the effects of controlled dietary interventions among chronic kidney disease patients are needed to determining the optimal target for nutritional therapy.

Metabolic acidosis of chronic kidney disease and subclinical cardiovascular disease markers: Friend or foe?

The effect of chronic metabolic acidosis (MA) on cardiovascular disease (CVD) in the setting of chronic kidney disease (CKD) is largely unknown. Therefore, we aimed to study this relationship in nondialysis CKD patients.This cross-sectional, single-center study prospectively enrolled 95 clinically stable CKD patients (median age 61 (58, 65) years, 60% male, median eGFR 27 (22, 32) mL/min). Data on CKD etiology, CVD history, CVD traditional, and nontraditional risk factors were obtained. Also, markers of subclinical CVD were assessed: intima-media thickness (IMT), abdominal aortic calcifications (Kauppila score-AACs), cardio-ankle vascular index (CAVI), ankle-brachial index (ABI), ejection fraction, and interventricular septum thickness. Using the serum bicarbonate cutoff value of 22 mEq/L, comparisons between MA (<22 mEq/L; 43 patients) and non-MA (≥22 mEq/L; 52 patients) groups were performed.Vascular (40%), tubulointerstitial (24%), and glomerular (22%) nephropathies were the main causes of CKD. Twenty-three percent of patients had diabetes mellitus, but only 5% were considered to have diabetic nephropathy. Patients with chronic MA had lower eGFR (P < .01), higher iPTH (P = .01), higher serum phosphate (P < .01), and increased serum cholesterol (P = .04) and triglycerides (P = .01).Higher ABI (P = .04), lower IMT (P = .03), CAVI (P = .05), and AACs (P = .03) were found in patients with chronic MA.Separate binomial logistic regression models were performed using ABI (cutoff 0.9), CAVI (cutoff 9), IMT (cutoff 0.1 cm), and AACs (cutoff 1) as dependent variables. MA was used as independent variable and adjustments were made for iPTH, serum phosphate, eGFR, proteinuria, cholesterol, triglycerides, CVD score. The absence of MA was retained as an independent predictor only for the presence of AACs.In conclusion, the present study shows a potential advantageous effect of MA on vascular calcifications in predialysis CKD patients. Thus, a guideline relaxation of the serum bicarbonate target might prove to be beneficial in CKD patients at high risk of vascular calcifications. However, one should always consider the negative effects of MA. Therefore, additional research is warranted before any clear clinical recommendation.

Oral Bicarbonate Slows Decline of Residual Renal Function in Peritoneal Dialysis Patients

BACKGROUND/AIMS

Metabolic acidosis is a common consequence of end-stage renal disease (ESRD) which may result in a substantial adverse outcome. The effect of oral bicarbonate on the preservation of residual renal function (RRF) in peritoneal dialysis (PD) patients has been rarely reported.

METHODS

We randomly assigned 40 continuous ambulatory peritoneal dialysis (CAPD) patients to the oral bicarbonate group or placebo group at a 1: 1 ratio. All enrollments were followed for a duration of 104 weeks. We took residual creatinine clearance (CCr), a measure of residual renal function (RRF), as the primary outcome. Residual CCr was calculated as the average of urea and creatinine clearance from a 24-hour urine collection.

RESULTS

Thirteen patients in the placebo group and 15 patients in the treatment group completed the 104 weeks of follow-up with a comparable dropout rate (placebo group: 35% vs treatment group: 25%). Compared with the placebo group, serum bicarbonate in treatment group was significantly increased at each time point, and oral bicarbonate resulted in a slower declining rate of residual CCr (F=5.113, p=0.031). Baseline residual CCr at enrollment also had a significant effect on residual CCr (F=168.779, P<0.001). Charlson Comorbidity Index which was adopted to calculate a comorbidity score had no significant effect on residual CCr loss (F=0.168, P=0.685).

CONCLUSION

Oral bicarbonate may have a RRF preserving effect in CAPD patients, and a normal to high level of serum bicarbonate (≥24mmol/L) may be appropriate for RRF preservation.

Adverse Effects of the Metabolic Acidosis of Chronic Kidney Disease

The kidney has the principal role in the maintenance of acid-base balance, and therefore, a fall in renal net acid excretion and positive H⁺ balance often leading to reduced serum [HCO₃^-] are observed in the course of CKD. This metabolic acidosis can be associated with muscle wasting, development or exacerbation of bone disease, hypoalbuminemia, increased inflammation, progression of CKD, protein malnutrition, alterations in insulin, leptin, and growth hormone, and increased mortality. Importantly, some of the adverse effects can be observed even in the absence of overt hypobicarbonatemia. Administration of base decreases muscle wasting, improves bone disease, restores responsiveness to insulin, slows progression of CKD, and possibly reduces mortality. Base is recommended when serum [HCO₃^-] is <22 mEq/L, but the target serum [HCO₃^-] remains unclear. Evidence that increments of serum [HCO₃^-] >26 mEq/L might be associated with worsening of cardiovascular disease adds complexity to treatment decisions. Further study of the mechanisms through which positive H⁺ balance in CKD contributes to its various adverse effects and the pathways involved in mediating the benefits and complications of base therapy is warranted.

Metabolic acidosis is common and associates with disease progression in children with chronic kidney disease

Recent studies in adult chronic kidney disease (CKD) suggest that metabolic acidosis is associated with faster decline in estimated glomerular filtration rate (eGFR). Alkali therapies improve the course of kidney disease. Here we investigated the prevalence and determinants of abnormal serum bicarbonate values and whether metabolic acidosis may be deleterious to children with CKD. Associations between follow-up serum bicarbonate levels categorized as under 18, 18 to under 22, and 22 or more mmol/l and CKD outcomes in 704 children in the Cardiovascular Comorbidity in Children with CKD Study, a prospective cohort of pediatric patients with CKD stages 3-5, were studied. The eGFR and serum bicarbonate were measured every six months. At baseline, the median eGFR was 27 ml/min/1.73m² and median serum bicarbonate level 21 mmol/l. During a median follow-up of 3.3 years, the prevalence of metabolic acidosis (serum bicarbonate under 22 mmol/l) was 43%, 60%, and 45% in CKD stages 3, 4, and 5, respectively. In multivariable analysis, the presence of metabolic acidosis as a time-varying covariate was significantly associated with log serum parathyroid hormone through the entire follow-up, but no association with longitudinal growth was found. A total of 211 patients reached the composite endpoint (ESRD or 50% decline in eGFR). In a multivariable Cox model, children with time-varying serum bicarbonate under 18 mmol/l had a significantly higher risk of CKD progression compared to those with a serum bicarbonate of 22 or more mmol/l (adjusted hazard ratio 2.44; 95% confidence interval 1.43-4.15). Thus, metabolic acidosis is a common complication in pediatric patients with CKD and may be a risk factor for secondary hyperparathyroidism and kidney disease progression.

Autophagy and kidney inflammation

Inflammation plays a pivotal role in pathophysiological processes of kidney diseases. Macroautophagy/autophagy plays multiple roles in inflammatory responses, and the regulation of inflammation by autophagy has great potential as a treatment for damaged kidneys. A growing body of evidence suggests autophagy protects kidney from versatile kidney inflammatory insults, including those that are acute, chronic, metabolic, and aging-related. It is noteworthy that, in kidney, mitophagy is active, and damaged lysosomes are removed by autophagy. In this mode, autophagy suppresses inflammation to protect the kidney. Systemic inflammation also affects the kidney via pro-inflammatory cytokines and infiltration of inflammatory cells, and autophagy also has a regulatory role in systemic inflammation. This review focuses on the roles of autophagy in kidney diseases and aging through inflammation, and discusses the potential usage of autophagy as an inflammatory modulator for the treatment of kidney diseases.

Role of Acid-Base Homeostasis in Diabetic Kidney Disease

PURPOSE OF REVIEW

Acid-base homeostasis is impaired in chronic kidney disease (CKD) and may contribute to disease progression. Diabetes, a major cause of CKD worldwide, may exacerbate acidosis further due to differences in acid production and excretion. Here, we review the role of abnormal acid-base homeostasis in the pathogenesis and progression of diabetes and diabetic kidney disease.

RECENT FINDINGS

Acidosis and dietary acid loading may contribute to the development and worsening of insulin resistance and hypertension, thereby promoting diabetes and diabetic CKD. However, although metabolic acidosis associates with progression of CKD generally, the results in diabetic CKD are mixed. Data suggests that metabolic acid production in diabetes may be higher than would be predicted based on dietary intake alone, and new observational data suggests that this higher diet-independent acid production could potentially be protective. The role of acid-base homeostasis in diabetic CKD progression is complex and must consider differences in endogenous acid production and excretion in diabetes. Ongoing observational and interventional studies in this field should consider the unique physiology of diabetes.

Possible Mechanisms of Cardiac Contractile Dysfunction and Electrical Changes in Ammonium Chloride Induced Chronic Metabolic Acidosis in Wistar Rats

Metabolic acidosis could occur due to either endogenous acids accumulation or bicarbonate loss from the gastrointestinal tract or commonly from the kidney. This study aimed to investigate the possible underlying mechanism(s) of chronic acidosis-induced cardiac contractile and electrical changes in rats. Twenty four adult Wistar rats, of both sexes, were randomly divided into control group and chronic metabolic acidosis group, which received orally 0.28 M NH4Cl in the drinking water for 2 weeks. At the end of experimental period, systolic and diastolic blood pressure values were measured. On the day of sacrifice, rats were anesthetized by i.p. pentobarbitone (40 mg/kg b.w.), transthoracic echocardiography and ECG were performed. Blood samples were obtained from abdominal aorta for complete blood count and determination of pH, bicarbonate, chloride, sodium, potassium, troponin I, CK-MB, IL-6, renin and aldosterone levels. Hearts from both groups were studied for cardiac tissue IL-6 and aldosterone in addition to histopathological examination. Compared to control group, chronic metabolic acidosis group showed anemia, significant systolic and diastolic hypotension accompanied by significant reduction of ejection fraction and fraction of shortening, significant bradycardia, prolonged QTc interval and higher widened T wave as well as significantly elevated plasma levels of renin, aldosterone, troponin I, CK-MB and IL-6, and cardiac tissue aldosterone and IL-6. The left ventricular wall of the acidosis group showed degenerated myocytes with fibrosis and apoptosis. Thus, chronic metabolic acidosis induced negative inotropic and chronotropic effects and cardiomyopathy, possibly by elevated aldosterone and IL-6 levels released from the cardiac tissue.

Association between Low Serum Bicarbonate Concentrations and Cardiovascular Disease in Patients in the End-Stage of Renal Disease

BACKGROUND

Metabolic acidosis, a common condition particularly in the end-stage of renal disease patients, results in malnutrition, inflammation and oxidative stress. In this study, we focused on the association between low serum bicarbonate and cardiovascular disease in patients on intermittent dialysis.

METHODS

We studied 52 on-line-pre-dilution hemodiafiltration (on-l HDF) patients, 32 males and 20 females, with a mean age of 58.01 ± 15.4 years old. Metabolic acidosis was determined by serum bicarbonate concentrations less than 22 mmol/L. Residual renal function (RRF) was defined by interdialytic urine volume. Kaplan-Meier curves and Cox regression models were performed to predict coronary artery disease (CAD), defined by ejection fraction <50%, or diastolic dysfunction congestive heart failure (CHF) and peripheral vascular disease (PVD).

RESULTS

Kaplan-Meier analyses showed that a lower or higher than 22 mmol/L serum bicarbonate metabolic acidosis status was significantly associated with both PVD and diastolic dysfunction (log-rank = 5.07, p = 0.02 and log-rank = 5.84, p = 0.01, respectively). A similar prevalence of serum bicarbonate on CAD or CHF by low ejection fraction was not shown. The RRF was associated with PVD event and serum bicarbonate less than 22 mmol/L (log-rank = 5.49, p = 0.01 and log-rank = 3.9, p = 0.04, respectively). Cox regression analysis revealed that serum bicarbonate and RRF were significant risk factors for PVD after adjustment for confounders. Furthermore, RRF adjusted for covariates was shown to be a significant risk factor for diastolic dysfunction.

CONCLUSION

Low serum bicarbonate was associated with peripheral vascular disease and diastolic dysfunction in intermittent dialysis. The residual renal function may impact patients' outcomes through its relationship with metabolic acidosis status, particularly for peripheral vascular disease manifestation.

Association of Fluid Status and Body Composition with Physical Function in Patients with Chronic Kidney Disease

Background

Impairment of physical function and abnormal body composition are the major presentations in patients with chronic kidney disease (CKD). The aim of this study is to investigate the relationship between body composition and physical function in CKD patients.

Methods

This cross-sectional study enrolled 172 of CKD stages 1–5 from February 2013 to September 2013. Handgrip strength (upper extremity muscle endurance), 30-second chair-stand test (lower extremity muscle endurance) and 2-minute step test (cardiorespiratory endurance) were used as indices of physical function. Body composition, including fluid status (extracellular water/total body water, ECW/TBW), lean tissue index (LTI), and fat tissue index (FTI), was measured using a bioimpedance spectroscopy method.

Results

All patients with high ECW/TBW had lower handgrip strength and 30-second chair-stand than those with low ECW/TBW (P<0.001 and P = 0.002). CKD patients with high FTI had lower handgrip strength and 30-second chair-stand than those with low FTI (P<0.001 and P = 0.002). These patients with low LTI had lower handgrip strength than those with high LTI (P = 0.04). In multivariate analysis, high ECW/TBW was positively associated with decreased handgrip strength (β = -41.17, P = 0.03) in CKD patients. High FTI was significantly correlated with decreased times of 30-second chair-stand (β = -0.13, P = 0.01). There was no significant relationship between body composition and 2-minute step test.

Conclusions

Our results show a significant association of impaired upper and lower extremity muscle endurance with high fluid status and fat tissue. Evaluation of body composition may assist in indentifying physical dysfunction earlier in CKD patients.