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Tyson CC, Luciano A, Modliszewski JL, Corcoran DL, Bain JR, Muehlbauer M, Ilkayeva O, Pourafshar S, Allen J, Bowman C, Gung J, Asplin JR, Pendergast J, Svetkey LP, Lin PH, Scialla JJ. Effect of Bicarbonate on Net Acid Excretion, Blood Pressure, and Metabolism in Patients With and Without CKD: The Acid Base Compensation in CKD Study. Am J Kidney Dis 2021; 78:38-47. [PMID: 33810868 DOI: 10.1053/j.ajkd.2020.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 10/10/2020] [Indexed: 11/11/2022]
Abstract
RATIONALE & OBJECTIVE Patients with CKD are at elevated risk of metabolic acidosis due to impaired net acid excretion (NAE). Identifying early markers of acidosis may guide prevention in chronic kidney disease (CKD). This study compared NAE in participants with and without CKD, as well as the NAE, blood pressure (BP), and metabolomic response to bicarbonate supplementation. STUDY DESIGN Randomized order, cross-over study with controlled feeding. SETTING & PARTICIPANTS Participants consisted of 8 patients with CKD (estimated glomerular filtration rate 30-59mL/min/1.73m2 or 60-70mL/min/1.73m2 with albuminuria) and 6 patients without CKD. All participants had baseline serum bicarbonate concentrations between 20 and 28 mEq/L; they did not have diabetes mellitus and did not use alkali supplements at baseline. INTERVENTION Participants were fed a fixed-acid-load diet with bicarbonate supplementation (7 days) and with sodium chloride control (7 days) in a randomized order, cross-over fashion. OUTCOMES Urine NAE, 24-hour ambulatory BP, and 24-hour urine and plasma metabolomic profiles were measured after each period. RESULTS During the control period, mean NAE was 28.3±10.2 mEq/d overall without differences across groups (P=0.5). Urine pH, ammonium, and citrate were significantly lower in CKD than in non-CKD (P<0.05 for each). Bicarbonate supplementation reduced NAE and urine ammonium in the CKD group, increased urine pH in both groups (but more in patients with CKD than in those without), and increased; urine citrate in the CKD group (P< 0.2 for interaction for each). Metabolomic analysis revealed several urine organic anions were increased with bicarbonate in CKD, including 3-indoleacetate, citrate/isocitrate, and glutarate. BP was not significantly changed. LIMITATIONS Small sample size and short feeding duration. CONCLUSIONS Compared to patients without CKD, those with CKD had lower acid excretion in the form of ammonium but also lower base excretion such as citrate and other organic anions, a potential compensation to preserve acid-base homeostasis. In CKD, acid excretion decreased further, but base excretion (eg, citrate) increased in response to alkali. Urine citrate should be evaluated as an early and responsive marker of impaired acid-base homeostasis. FUNDING National Institute of Diabetes and Digestive and Kidney Diseases and the Duke O'Brien Center for Kidney Research. TRIAL REGISTRATION Registered at ClinicalTrials.gov with study number NCT02427594.
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Affiliation(s)
- Crystal C Tyson
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - Alison Luciano
- Center for the Study of Aging and Human Development, Duke University School of Medicine, Durham, NC
| | - Jennifer L Modliszewski
- Center for Genomic and Computational Biology, Duke University School of Medicine, Durham, NC; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC
| | - David L Corcoran
- Center for Genomic and Computational Biology, Duke University School of Medicine, Durham, NC; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC
| | - James R Bain
- Department of Medicine, Duke University School of Medicine, Durham, NC; Center for the Study of Aging and Human Development, Duke University School of Medicine, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC
| | - Michael Muehlbauer
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC
| | - Olga Ilkayeva
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC
| | - Shirin Pourafshar
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA
| | - Jenifer Allen
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - Cassandra Bowman
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - Joseph Gung
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - John R Asplin
- Litholink Corp, Laboratory Corporation of America Holdings, Chicago, IL
| | - Jane Pendergast
- Department of Medicine, Duke University School of Medicine, Durham, NC; Center for the Study of Aging and Human Development, Duke University School of Medicine, Durham, NC; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC
| | - Laura P Svetkey
- Department of Medicine, Duke University School of Medicine, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC
| | - Pao-Hwa Lin
- Department of Medicine, Duke University School of Medicine, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC
| | - Julia J Scialla
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA.
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