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Mohebbi N, Ritter A, Wiegand A, Graf N, Dahdal S, Sidler D, Arampatzis S, Hadaya K, Mueller TF, Wagner CA, Wüthrich RP. Sodium bicarbonate for kidney transplant recipients with metabolic acidosis in Switzerland: a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial. Lancet 2023; 401:557-567. [PMID: 36708734 DOI: 10.1016/s0140-6736(22)02606-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 11/17/2022] [Accepted: 12/13/2022] [Indexed: 01/27/2023]
Abstract
BACKGROUND Metabolic acidosis is common in kidney transplant recipients and is associated with declining graft function. Sodium bicarbonate treatment effectively corrects metabolic acidosis, but no prospective studies have examined its effect on graft function. Therefore, we aimed to test whether sodium bicarbonate treatment would preserve graft function and slow the progression of estimated glomerular filtration rate (GFR) decline in kidney transplant recipients. METHODS The Preserve-Transplant Study was a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial at three University Hospitals in Switzerland (Zurich, Bern, and Geneva), which recruited adult (aged ≥18 years) male and female long-term kidney transplant recipients if they had undergone transplantation more than 1 year ago. Key inclusion criteria were an estimated GFR between 15 mL/min per 1·73 m2 and 89 mL/min per 1·73 m2, stable allograft function in the last 6 months before study inclusion (<15% change in serum creatinine), and a serum bicarbonate of 22 mmol/L or less. We randomly assigned patients (1:1) to either oral sodium bicarbonate 1·5-4·5 g per day or matching placebo using web-based data management software. Randomisation was stratified by study centre and gender using a permuted block design to guarantee balanced allocation. We did multi-block randomisation with variable block sizes of two and four. Treatment duration was 2 years. Acid-resistant soft gelatine capsules of 500 mg sodium bicarbonate or matching 500 mg placebo capsules were given at an initial dose of 500 mg (if bodyweight was <70 kg) or 1000 mg (if bodyweight was ≥70 kg) three times daily. The primary endpoint was the estimated GFR slope over the 24-month treatment phase. The primary efficacy analyses were applied to a modified intention-to-treat population that comprised all randomly assigned participants who had a baseline visit. The safety population comprised all participants who received at least one dose of study drug. The trial is registered with ClinicalTrials.gov, NCT03102996. FINDINGS Between June 12, 2017, and July 10, 2019, 1114 kidney transplant recipients with metabolic acidosis were assessed for trial eligibility. 872 patients were excluded and 242 were randomly assigned to the study groups (122 [50%] to the placebo group and 120 [50%] to the sodium bicarbonate group). After secondary exclusion of two patients, 240 patients were included in the intention-to-treat analysis. The calculated yearly estimated GFR slopes over the 2-year treatment period were a median -0·722 mL/min per 1·73 m2 (IQR -4·081 to 1·440) and mean -1·862 mL/min per 1·73 m2 (SD 6·344) per year in the placebo group versus median -1·413 mL/min per 1·73 m2 (IQR -4·503 to 1·139) and mean -1·830 mL/min per 1·73 m2 (SD 6·233) per year in the sodium bicarbonate group (Wilcoxon rank sum test p=0·51; Welch t-test p=0·97). The mean difference was 0·032 mL/min per 1·73 m2 per year (95% CI -1·644 to 1·707). There were no significant differences in estimated GFR slopes in a subgroup analysis and a sensitivity analysis confirmed the primary analysis. Although the estimated GFR slope did not show a significant difference between the treatment groups, treatment with sodium bicarbonate effectively corrected metabolic acidosis by increasing serum bicarbonate from 21·3 mmol/L (SD 2·6) to 23·0 mmol/L (2·7) and blood pH from 7·37 (SD 0·06) to 7·39 (0·04) over the 2-year treatment period. Adverse events and serious adverse events were similar in both groups. Three study participants died. In the placebo group, one (1%) patient died from acute respiratory distress syndrome due to SARS-CoV-2 and one (1%) from cardiac arrest after severe dehydration following diarrhoea with hypotension, acute kidney injury, and metabolic acidosis. In the sodium bicarbonate group, one (1%) patient had sudden cardiac death. INTERPRETATION In adult kidney transplant recipients, correction of metabolic acidosis by treatment with sodium bicarbonate over 2 years did not affect the decline in estimated GFR. Thus, treatment with sodium bicarbonate should not be generally recommended to preserve estimated GFR (a surrogate marker for graft function) in kidney transplant recipients with chronic kidney disease who have metabolic acidosis. FUNDING Swiss National Science Foundation.
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Affiliation(s)
- Nilufar Mohebbi
- Division of Nephrology, University Hospital, Zurich, Switzerland.
| | - Alexander Ritter
- Division of Nephrology, University Hospital, Zurich, Switzerland
| | - Anna Wiegand
- Division of Nephrology, University Hospital, Zurich, Switzerland
| | | | - Suzan Dahdal
- Division of Nephrology and Hypertension, Inselspital, Bern, Switzerland
| | - Daniel Sidler
- Division of Nephrology and Hypertension, Inselspital, Bern, Switzerland
| | | | - Karine Hadaya
- Division of Nephrology and Hypertension, University Hospital, Geneva, Switzerland
| | - Thomas F Mueller
- Division of Nephrology, University Hospital, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
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Elsebai MF, Habib ESE. Blood pH and COVID-19. Arch Pharm (Weinheim) 2023; 356:e2200558. [PMID: 36690587 DOI: 10.1002/ardp.202200558] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/31/2022] [Accepted: 01/02/2023] [Indexed: 01/25/2023]
Abstract
The coronavirus disease 2019 (COVID-19) pandemic is a worldwide war. Raising the blood pH might be a crucial strategy to chase COVID-19. The human blood is slightly alkaline, which is essential for cell metabolism, normal physiology, and balanced immunity since all of these biological processes are pH-dependent. Varieties of physiologic derangements occur when the blood pH is disrupted. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) proliferates in acidic blood that magnifies the severity of COVID-19. On the other side, blood acidemia is linked to increased morbidity and mortality because of its complications on immunity, especially in the elderly and in critical diseases such as cancer, musculoskeletal degradation, renal, cardiac, and pulmonary disorders, which result in many pathological disorders such as osteomalacia, and disturbing the hematopoiesis. Additionally, acidemia of the blood facilitates viral infection and progression. Thus, correcting the acid-base balance might be a crucial strategy for the treatment of COVID-19, which might be attributed to the distraction of the viral spike protein to its cognate receptor angiotensin-converting enzyme 2 and supporting the over-taxed immunity.
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Affiliation(s)
- Mahmoud Fahmi Elsebai
- Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - El-Sayed E Habib
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
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Tariq H, Dobre M. Metabolic acidosis post kidney transplantation. Front Physiol 2022; 13:989816. [PMID: 36082221 PMCID: PMC9445136 DOI: 10.3389/fphys.2022.989816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/01/2022] [Indexed: 11/23/2022] Open
Abstract
Metabolic acidosis, a common complication in patients with chronic kidney disease (CKD), results in a multitude of deleterious effects. Though the restoration of kidney function following transplantation is generally accompanied by a correction of metabolic acidosis, a subset of transplant recipients remains afflicted by this ailment and its subsequent morbidities. The vulnerability of kidney allografts to metabolic acidosis can be attributed to reasons similar to pathogenesis of acidosis in non-transplant CKD, and to transplant specific causes, including donor related, recipient related, immune mediated factors, and immunosuppressive medications. Correction of metabolic acidosis in kidney transplantation either with alkali therapy or through dietary manipulations may have potential benefits and the results of such clinical trials are eagerly awaited. This review summarizes the published evidence on the pathogenesis and clinical consequences of chronic metabolic acidosis in kidney transplant recipients.
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Affiliation(s)
- Hafsa Tariq
- Division of Nephrology, University of Rochester Medical Center, Rochester, NY, United States
| | - Mirela Dobre
- Division of Nephrology and Hypertension, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, United States
- *Correspondence: Mirela Dobre,
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Imenez Silva PH, Mohebbi N. Kidney metabolism and acid-base control: back to the basics. Pflugers Arch 2022; 474:919-934. [PMID: 35513635 PMCID: PMC9338915 DOI: 10.1007/s00424-022-02696-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 01/18/2023]
Abstract
Kidneys are central in the regulation of multiple physiological functions, such as removal of metabolic wastes and toxins, maintenance of electrolyte and fluid balance, and control of pH homeostasis. In addition, kidneys participate in systemic gluconeogenesis and in the production or activation of hormones. Acid-base conditions influence all these functions concomitantly. Healthy kidneys properly coordinate a series of physiological responses in the face of acute and chronic acid-base disorders. However, injured kidneys have a reduced capacity to adapt to such challenges. Chronic kidney disease patients are an example of individuals typically exposed to chronic and progressive metabolic acidosis. Their organisms undergo a series of alterations that brake large detrimental changes in the homeostasis of several parameters, but these alterations may also operate as further drivers of kidney damage. Acid-base disorders lead not only to changes in mechanisms involved in acid-base balance maintenance, but they also affect multiple other mechanisms tightly wired to it. In this review article, we explore the basic renal activities involved in the maintenance of acid-base balance and show how they are interconnected to cell energy metabolism and other important intracellular activities. These intertwined relationships have been investigated for more than a century, but a modern conceptual organization of these events is lacking. We propose that pH homeostasis indissociably interacts with central pathways that drive progression of chronic kidney disease, such as inflammation and metabolism, independent of etiology.
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Affiliation(s)
- Pedro Henrique Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Nilufar Mohebbi
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
- Praxis Und Dialysezentrum Zurich, Zurich, Switzerland
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Brown DD, Carroll M, Ng DK, Levy RV, Greenbaum LA, Kaskel FJ, Furth SL, Warady BA, Melamed ML, Dauber A. Longitudinal Associations between Low Serum Bicarbonate and Linear Growth in Children with CKD. KIDNEY360 2022; 3:666-676. [PMID: 35721607 PMCID: PMC9136912 DOI: 10.34067/kid.0005402021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/10/2022] [Indexed: 01/28/2023]
Abstract
Background Poor linear growth is a consequence of chronic kidney disease (CKD) that has been linked to adverse outcomes. Metabolic acidosis (MA) has been identified as a risk factor for growth failure. We investigated the longitudinal relationship between MA and linear growth in children with CKD and examined whether treatment of MA modified linear growth. Methods To describe longitudinal associations between MA and linear growth, we used serum bicarbonate levels, height measurements, and standard deviation (z scores) of children enrolled in the prospective cohort study Chronic Kidney Disease in Children. Analyses were adjusted for covariates recognized as correlating with poor growth, including demographic characteristics, glomerular filtration rate (GFR), proteinuria, calcium, phosphate, parathyroid hormone, and CKD duration. CKD diagnoses were analyzed by disease categories, nonglomerular or glomerular. Results The study population included 1082 children with CKD: 808 with nonglomerular etiologies and 274 with glomerular etiologies. Baseline serum bicarbonate levels ≤22 mEq/L were associated with worse height z scores in all children. Longitudinally, serum bicarbonate levels ≤18 and 19-22 mEq/L were associated with worse height z scores in children with nonglomerular CKD causes, with adjusted mean values of -0.39 (95% CI, -0.58 to -0.2) and -0.17 (95% CI, -0.28 to -0.05), respectively. Children with nonglomerular disease and more severe GFR impairment had a higher risk for worse height z score. A significant association was not found in children with glomerular diseases. We also investigated the potential effect of treatment of MA on height in children with a history of alkali therapy use, finding that only persistent users had a significant positive association between their height z score and higher serum bicarbonate levels. Conclusions We observed a longitudinal association between MA and lower height z score. Additionally, persistent alkali therapy use was associated with better height z scores. Future clinical trials of alkali therapy need to evaluate this relationship prospectively.
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Affiliation(s)
- Denver D. Brown
- Division of Nephrology, Children’s National Hospital, Washington, DC
| | - Megan Carroll
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Derek K. Ng
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Rebecca V. Levy
- Division of Pediatric Nephrology, University of Rochester Medical Center, Rochester, New York
| | - Larry A. Greenbaum
- Division of Pediatric Nephrology, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, Georgia
| | - Frederick J. Kaskel
- Division of Pediatric Nephrology, The Children’s Hospital at Montefiore, Bronx, New York
| | - Susan L. Furth
- Division of Pediatric Nephrology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Bradley A. Warady
- Division of Pediatric Nephrology, Children’s Mercy Hospital, Kansas City, Missouri
| | - Michal L. Melamed
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Andrew Dauber
- Division of Endocrinology, Children’s National Hospital, Washington, DC
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Kaneko S, Usui J, Takahashi K, Oda T, Yamagata K. Increased intrarenal post-glomerular blood flow is a key condition for the development of calcineurin inhibitor-induced renal tubular acidosis in kidney transplant recipients. Clin Transplant 2022; 36:e14648. [PMID: 35293652 DOI: 10.1111/ctr.14648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/04/2022] [Accepted: 03/08/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND Hyperchloremic metabolic acidosis (HCMA) from renal tubular acidosis (RTA) is common in kidney transplant (KT) recipients. Calcineurin inhibitors (CNIs) are a potential cause of RTA, and whether HCMA is a determinant of poor graft prognosis is controversial. METHODS The subjects were living-donor KT recipients (LDKTRs, n = 47) and matched donors (n = 43). All cases of rejection, extrarenal causes, and respiratory disorders were excluded. HCMA was defined as having a [Na+] - [Cl-] value of ≤ 34 or starting alkalization. We determined the potential causes of HCMA in LDKTRs at 3 months (m) and 1 year (y) post-KT. We examined renal hemodynamic parameters in 26 LDKTRs at 1 y post-KT: namely, glomerular filtration rate (GFR), renal plasma flow (RPF), filtration fraction (FF; GFR/RPF) and pre-/post-glomerular vascular resistance (pre-/postVR). RESULTS The HCMA incidence in the 3-m post-KT LDKTR group was higher than that of the donors (51.0% vs. 6.9%, p<0.001, adjusted odds ratio: 6.7-15.7). Among adjusted factors, the most dominant HCMA contributor was low hemoglobin concentration (Hb ≤12 g/dL). Compared to non-HCMA cases, HCMA patients had low FF and low post-VR (p = 0.008, 0.003, respectively) suggesting increased intrarenal post-glomerular blood flow. The high pathological score of alternative arteriolar hyalinosis (aah) ≥2 was a significant HCMA risk. The tacrolimus trough level was not high in HCMA but was significantly high in HCMA in the low post-VR setting (p = 0.002). CONCLUSION Among LDKTRs, low hemoglobin level is an important contributor to the manifestation of HCMA in the induction period, and increased intrarenal post-glomerular blood flow is a key condition for the development of CNI-induced RTA. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Shuzo Kaneko
- Department of Nephrology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.,Department of Nephrology, Itabashi Chuo Medical Center, Itabashi, Tokyo, Japan
| | - Joichi Usui
- Department of Nephrology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Kazuhiro Takahashi
- Department of Gastroenterological and Hepatobiliary Surgery and Organ Transplantation, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Tatsuya Oda
- Department of Gastroenterological and Hepatobiliary Surgery and Organ Transplantation, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kunihiro Yamagata
- Department of Nephrology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
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Ibrahim HN, Murad DN, Knoll GA. Thinking Outside the Box: Novel Kidney Protective Strategies in Kidney Transplantation. Clin J Am Soc Nephrol 2021; 16:1890-1897. [PMID: 33757985 PMCID: PMC8729499 DOI: 10.2215/cjn.15070920] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Despite the reduction in the incidence of acute rejection, a major risk factor for graft loss, there has been only modest improvement in long-term graft survival. Most cases of kidney graft loss have an identifiable cause that is not idiopathic fibrosis/atrophy or calcineurin inhibitor nephrotoxicity. Distinct immunologic and nonimmunologic factors conspire to lead to a common pathway of allograft fibrosis. It remains plausible that mitigating nonimmunologic damage using strategies proven effective in native kidney disease may yield benefit in kidney transplantation. In this review, we will focus on nonimmunologic aspects of kidney transplant care that may prove to be valuable adjuncts to a well-managed immunosuppression regimen. Topics to be addressed include the roles of hypertension and agents used to treat it, lipid lowering, sodium and water intake, elevated uric acid, metabolic acidosis, and the use of sodium-glucose cotransporter 2 inhibitors on long-term kidney transplant health.
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Affiliation(s)
- Hassan N. Ibrahim
- Division of Renal Diseases and Hypertension, Department of Medicine, Houston Methodist Hospital, Houston, Texas
| | - Dina N. Murad
- Division of Renal Diseases and Hypertension, Department of Medicine, Houston Methodist Hospital, Houston, Texas
| | - Greg A. Knoll
- Division of Nephrology, Department of Medicine, Ottawa Hospital and Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Association of serum bicarbonate with graft survival and mortality in kidney transplant recipients. J Nephrol 2021; 35:619-627. [PMID: 34843097 DOI: 10.1007/s40620-021-01197-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Metabolic acidosis is an independent risk factor for kidney disease progression with a high prevalence after kidney transplantation (KTx). Remarkably, it is still unclear if there is an impact of metabolic acidosis on graft function and death after KTx. Thus, we wanted to investigate if serum bicarbonate is associated with long-term graft outcome and mortality after KTx. METHODS We performed a single-center retrospective study including adult de novo KTx patients between 1999 and 2015. Cox proportional hazard model was used to analyze a possible association between time-dependent serum bicarbonate measurements and graft failure or death. RESULTS Four hundred thirty KTRs were included in the analysis with a mean age of 50.9 ± 13.4 years. Mean observation time was 4.7 ± 2.8 years. Two hundred eighty-four (66%) patients were male and 318 (74%) had received a deceased donor kidney transplant. Mean bicarbonate and eGFR levels 1 year post-transplant amounted to 22.9 ± 3.1 mEq/L and 61 ± 26 ml/min/1.73 m2, respectively. Prevalence of metabolic acidosis was 31% 1 year after transplantation. Fourteen (3%) patients died and 31 (7%) suffered from graft failure. Higher bicarbonate levels were associated with significantly lower hazards for graft failure (Hazard Ratio (HR) = 0.88; 95% Confidence Interval (CI): 0.79-0.98) and mortality (HR = 0.79; 95% CI 0.66-0.93) after adjusting for potential confounders such as age, donor type and time-varying eGFR. CONCLUSIONS Our analysis showed that higher serum bicarbonate levels are positively associated with long-term graft and patient survival in kidney transplant recipients. Thus, serum bicarbonate may serve as a predictor and independent risk factor for graft and patient outcome after KTx as has been previously shown for patients with CKD.
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Stenson EK, Kendrick J. An Apple a Day Keeps Dialysis Away. Clin J Am Soc Nephrol 2021; 16:1306-1308. [PMID: 34497106 PMCID: PMC8729567 DOI: 10.2215/cjn.09610721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Erin K Stenson
- Department of Pediatrics, Section of Critical Care Medicine, Children's Hospital Colorado and University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jessica Kendrick
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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10
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Silva PHI, Wiegand A, Daryadel A, Russo G, Ritter A, Gaspert A, Wüthrich RP, Wagner CA, Mohebbi N. Acidosis and alkali therapy in patients with kidney transplant is associated with transcriptional changes and altered abundance of genes involved in cell metabolism and acid-base balance. Nephrol Dial Transplant 2021; 36:1806-1820. [PMID: 34240183 DOI: 10.1093/ndt/gfab210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Metabolic acidosis occurs frequently in patients with kidney transplant and is associated with higher risk for and accelerated loss of graft function. To date, it is not known whether alkali therapy in these patients improves kidney function and whether acidosis and its therapy is associated with altered expression of proteins involved in renal acid-base metabolism. METHODS We collected retrospectively kidney biopsies from 22 patients. Of these patients, 9 had no acidosis, 9 had metabolic acidosis (plasma HCO3- < 22 mmol/l), and 4 had acidosis and received alkali therapy. We performed transcriptome analysis and immunohistochemistry for proteins involved in renal acid-base handling. RESULTS We found the expression of 40 transcripts significantly changed between kidneys from non-acidotic and acidotic patients. These genes are mostly involved in proximal tubule amino acid and lipid metabolism and energy homeostasis. Three transcripts were fully recovered by alkali therapy: the Kir4.2 K+-channel, an important regulator of proximal tubule HCO3--metabolism and transport, ACADSB and SHMT1, genes involved in beta-oxidation and methionine metabolism. Immunohistochemistry showed reduced staining for the proximal tubule NBCe1 HCO3- transporter in kidneys from acidotic patients that recovered with alkali therapy. In addition, the HCO3-exchanger pendrin was affected by acidosis and alkali therapy. CONCLUSIONS Metabolic acidosis in kidney transplant recipients is associated with alterations in the renal transcriptome that are partly restored by alkali therapy. Acid-base transport proteins mostly from proximal tubule were also affected by acidosis and alkali therapy suggesting that the downregulation of critical players contributes to metabolic acidosis in these patients.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Anna Wiegand
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Arezoo Daryadel
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Giancarlo Russo
- Functional Genomics Center Zürich, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - Alexander Ritter
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Ariana Gaspert
- Department of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Rudolf P Wüthrich
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
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Yeung SMH, Gomes-Neto AW, Osté MCJ, van den Berg E, Kootstra-Ros JE, Sanders JSF, Berger SP, Carrero JJ, De Borst MH, Navis GJ, Bakker SJL. Net Endogenous Acid Excretion and Kidney Allograft Outcomes. Clin J Am Soc Nephrol 2021; 16:1398-1406. [PMID: 34135022 PMCID: PMC8729579 DOI: 10.2215/cjn.00780121] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/07/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES High dietary acid load may accelerate a decline in kidney function. We prospectively investigated whether dietary acid load is associated with graft outcomes in kidney transplant recipients, and whether venous bicarbonate mediates this association. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We used data from 642 kidney transplant recipients with a functioning graft ≥1 year after transplantation. Net endogenous acid production was estimated using food frequency questionnaires and, alternatively, 24-hour urinary urea and potassium excretion to estimate net endogenous acid production. We defined the composite kidney end point as a doubling of plasma creatinine or graft failure. Multivariable Cox regression analyses, adjusted for potential confounders, were used to study the associations of dietary acid load with the kidney end point. We evaluated potential mediation effects of venous bicarbonate, urinary bicarbonate excretion, urinary ammonium excretion, titratable acid excretion, and net acid excretion on the association between net endogenous acid production and the kidney end point. RESULTS The median net endogenous acid production using food frequency questionnaires and net endogenous acid production using urinary excretion were 40 (interquartile range, 35-45) and 54 (interquartile range, 44-66) mEq/day, respectively. During a median follow-up of 5.3 years (interquartile range, 4.1-6.0), 121 (19%) participants reached the kidney end point. After multivariable adjustment, net endogenous acid production using food frequency questionnaires and net endogenous acid production using urinary excretion (per SD higher) were independently associated with higher risk for kidney end point (hazard ratio, 1.33; 95% confidence interval, 1.12 to 1.57, P=0.001 and hazard ratio, 1.44; 95% confidence interval, 1.24 to 1.69, P<0.001, respectively). Baseline venous bicarbonate mediated 20% of the association between net endogenous acid production using food frequency questionnaires and the kidney end point. Baseline venous bicarbonate, urinary ammonium excretion, and net acid excretion mediated 25%, -14%, and -18%, respectively, of the association between net endogenous acid production using urinary excretion and the kidney end point. CONCLUSIONS Higher dietary acid load was associated with a higher risk of doubling of plasma creatinine or graft failure, and this association was partly mediated by venous bicarbonate, urinary ammonium, and net acid excretion.
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Affiliation(s)
- Stanley M H Yeung
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Antonio W Gomes-Neto
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Maryse C J Osté
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Else van den Berg
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Jenny E Kootstra-Ros
- Department of Laboratory Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Jan Stephan F Sanders
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Stefan P Berger
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Juan Jesus Carrero
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Martin H De Borst
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Gerjan J Navis
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
| | - Stephan J L Bakker
- Department of Internal Medicine, University Medical Centre Groningen, Groningen, The Netherlands
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12
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Ritter A, Mohebbi N. Causes and Consequences of Metabolic Acidosis in Patients after Kidney Transplantation. Kidney Blood Press Res 2020; 45:792-801. [PMID: 33040055 DOI: 10.1159/000510158] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/01/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Metabolic acidosis (MA) is a common complication in kidney transplantation (KTx). It is more prevalent in KTx than in CKD, and it occurs at higher glomerular filtration rates. The pathophysiologic understanding of MA in KTx and its clinical impact has been highlighted by few recent studies. However, no guidelines exist yet for the treatment of MA after KTx. SUMMARY MA in KTx seems to share pathophysiologic mechanisms with CKD, such as impaired ammoniagenesis. Additional kidney transplant-specific factors seem to alter not only the prevalence but also the phenotype of MA, which typically shows features of renal tubular acidosis. There is evidence that calcineurin inhibitors, immunological factors, process of donation, donor characteristics, and diet may contribute to MA occurrence. According to several mainly observational studies, MA seems to play a role in disturbed bone metabolism, cardiovascular morbidity, declining graft function, and mortality. A better understanding of the pathophysiology and evidence from randomized controlled trials, in particular, are needed to clarify the role of MA and the potential benefit of alkali treatment in KTx. Alkali therapy might not only be beneficial but also cost effective and safe. Key Messages: MA seems to be associated with several negative outcomes in KTx. A deeper understanding of the pathophysiology and clinical consequences of MA in KTx is crucial. Clinical trials will have to determine the potential benefits of alkali therapy.
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Affiliation(s)
- Alexander Ritter
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland, .,Praxis und Dialysezentrum Zürich-City, Zurich, Switzerland,
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Brown DD, Roem J, Ng DK, Reidy KJ, Kumar J, Abramowitz MK, Mak RH, Furth SL, Schwartz GJ, Warady BA, Kaskel FJ, Melamed ML. Low Serum Bicarbonate and CKD Progression in Children. Clin J Am Soc Nephrol 2020; 15:755-765. [PMID: 32467307 PMCID: PMC7274283 DOI: 10.2215/cjn.07060619] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 04/09/2020] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND OBJECTIVES Studies of adults have demonstrated an association between metabolic acidosis, as measured by low serum bicarbonate levels, and CKD progression. We evaluated this relationship in children using data from the Chronic Kidney Disease in Children study. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The relationship between serum bicarbonate and a composite end point, defined as 50% decline in eGFR or KRT, was described using parametric and semiparametric survival methods. Analyses were stratified by underlying nonglomerular and glomerular diagnoses, and adjusted for demographic characteristics, eGFR, proteinuria, anemia, phosphate, hypertension, and alkali therapy. RESULTS Six hundred and three participants with nonglomerular disease contributed 2673 person-years of follow-up, and 255 with a glomerular diagnosis contributed 808 person-years of follow-up. At baseline, 39% (237 of 603) of participants with nonglomerular disease had a bicarbonate level of ≤22 meq/L and 36% (85 of 237) of those participants reported alkali therapy treatment. In participants with glomerular disease, 31% (79 of 255) had a bicarbonate of ≤22 meq/L, 18% (14 of 79) of those participants reported alkali therapy treatment. In adjusted longitudinal analyses, compared with participants with a bicarbonate level >22 meq/L, hazard ratios associated with a bicarbonate level of <18 meq/L and 19-22 meq/L were 1.28 [95% confidence interval (95% CI), 0.84 to 1.94] and 0.91 (95% CI, 0.65 to 1.26), respectively, in children with nonglomerular disease. In children with glomerular disease, adjusted hazard ratios associated with bicarbonate level ≤18 meq/L and bicarbonate 19-22 meq/L were 2.16 (95% CI, 1.05 to 4.44) and 1.74 (95% CI, 1.07 to 2.85), respectively. Resolution of low bicarbonate was associated with a lower risk of CKD progression compared with persistently low bicarbonate (≤22 meq/L). CONCLUSIONS In children with glomerular disease, low bicarbonate was linked to a higher risk of CKD progression. Resolution of low bicarbonate was associated with a lower risk of CKD progression. Fewer than one half of all children with low bicarbonate reported treatment with alkali therapy. Long-term studies of alkali therapy's effect in patients with pediatric CKD are needed.
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Affiliation(s)
- Denver D. Brown
- Division of Pediatric Nephrology, Children’s National Hospital, Washington, DC
| | - Jennifer Roem
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Derek K. Ng
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Kimberly J. Reidy
- Division of Pediatric Nephrology, The Children’s Hospital at Montefiore, Bronx, New York
| | - Juhi Kumar
- Division of Pediatric Nephrology, Weill Cornell Medicine, New York, New York
| | | | - Robert H. Mak
- Division of Pediatric Nephrology, Rady Children’s Hospital San Diego, University of California San Diego, San Diego, California
| | - Susan L. Furth
- Division of Pediatric Nephrology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - George J. Schwartz
- Division of Pediatric Nephrology, University of Rochester, Rochester, New York
| | - Bradley A. Warady
- Division of Pediatric Nephrology, Children’s Mercy Hospital, Kansas City, Missouri
| | - Frederick J. Kaskel
- Division of Pediatric Nephrology, The Children’s Hospital at Montefiore, Bronx, New York
| | - Michal L. Melamed
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
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Farouk SS, Rein JL. The Many Faces of Calcineurin Inhibitor Toxicity-What the FK? Adv Chronic Kidney Dis 2020; 27:56-66. [PMID: 32147003 DOI: 10.1053/j.ackd.2019.08.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 08/01/2019] [Indexed: 02/07/2023]
Abstract
Calcineurin inhibitors (CNIs) are both the savior and Achilles' heel of kidney transplantation. Although CNIs have significantly reduced rates of acute rejection, their numerous toxicities can plague kidney transplant recipients. By 10 years, virtually all allografts will have evidence of CNI nephrotoxicity. CNIs have been strongly associated with hypertension, dyslipidemia, and new onset of diabetes after transplantation-significantly contributing to cardiovascular risk in the kidney transplant recipient. Multiple electrolyte derangements including hyperkalemia, hypomagnesemia, hypercalciuria, metabolic acidosis, and hyperuricemia may be challenging to manage for the clinician. Finally, CNI-associated tremor, gingival hyperplasia, and defects in hair growth can have a significant impact on the transplant recipient's quality of life. In this review, the authors briefly discuss the pharmacokinetics of CNI and discuss the numerous clinically relevant toxicities of commonly used CNIs, cyclosporine and tacrolimus.
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Avila-Poletti D, De Azevedo L, Iommi C, Heldal K, Musso CG. Hyperchloremic metabolic acidosis in the kidney transplant patient. Postgrad Med 2019; 131:171-175. [PMID: 30924703 DOI: 10.1080/00325481.2019.1592360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hyperchloremic metabolic acidosis of renal origin results from a defect in renal tubular acidification mechanism, and this tubular dysfunction can consist of an altered tubular proton secretion or bicarbonate reabsorption capability. Studies have documented that all forms of renal tubular acidosis (RTA), type I to IV, are documented in kidney transplant patients. Among RTA pathophysiologic mechanisms have been described the renal mass reduction, hyperkalemia, hyperparathyroidism, graft rejection, immunologic diseases, and some drugs such as renin-angiotensin-aldosterone blockers, and calcineurin inhibitors. RTA can lead to serious complications as is the case of muscle protein catabolism, muscle protein synthesis inhibition, renal osteodystrophy, renal damage progression, and anemia promotion. RTA should be treated by suppressing its etiologic factor (if it is possible), avoiding hyperkalemia, and/or supplying bicarbonate or a precursor (citrate). In conclusion: Hyperchloremic metabolic acidosis of renal origin is a relatively frequent complication in kidney transplantation patients, which can be harmful, and should be adequately treated in order to avoid its renal and systemic adverse effects.
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Affiliation(s)
- Debora Avila-Poletti
- a Human Physiology Department , Instituto Universitario del Hospital Italiano de Buenos Aires , Buenos Aires , Argentina
| | - Leticia De Azevedo
- a Human Physiology Department , Instituto Universitario del Hospital Italiano de Buenos Aires , Buenos Aires , Argentina
| | - Candela Iommi
- a Human Physiology Department , Instituto Universitario del Hospital Italiano de Buenos Aires , Buenos Aires , Argentina
| | - Kristian Heldal
- b Clinic of Internal Medicine, Telemark Hospital Trust , Skien , Norway.,c Institute of Clinical Medicine, Faculty of Medicine of University of Oslo , Oslo , Norway
| | - Carlos G Musso
- a Human Physiology Department , Instituto Universitario del Hospital Italiano de Buenos Aires , Buenos Aires , Argentina
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