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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 07; 78(1):38-47.AJ

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.

Authors+Show Affiliations

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.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.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.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.Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC.Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC.Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA.Department of Medicine, Duke University School of Medicine, Durham, NC.Department of Medicine, Duke University School of Medicine, Durham, NC.Department of Medicine, Duke University School of Medicine, Durham, NC.Litholink Corp, Laboratory Corporation of America Holdings, Chicago, IL.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.Department of Medicine, Duke University School of Medicine, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC.Department of Medicine, Duke University School of Medicine, Durham, NC; Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC.Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA. Electronic address: jscialla@virginia.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

33810868

Citation

Tyson, Crystal C., et al. "Effect of Bicarbonate On Net Acid Excretion, Blood Pressure, and Metabolism in Patients With and Without CKD: the Acid Base Compensation in CKD Study." American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation, vol. 78, no. 1, 2021, pp. 38-47.
Tyson CC, Luciano A, Modliszewski JL, et al. 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(1):38-47.
Tyson, C. C., Luciano, A., Modliszewski, J. L., Corcoran, D. L., Bain, J. R., Muehlbauer, M., Ilkayeva, O., Pourafshar, S., Allen, J., Bowman, C., Gung, J., Asplin, J. R., Pendergast, J., Svetkey, L. P., Lin, P. H., & Scialla, J. J. (2021). Effect of Bicarbonate on Net Acid Excretion, Blood Pressure, and Metabolism in Patients With and Without CKD: The Acid Base Compensation in CKD Study. American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation, 78(1), 38-47. https://doi.org/10.1053/j.ajkd.2020.10.015
Tyson CC, et al. 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(1):38-47. PubMed PMID: 33810868.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of Bicarbonate on Net Acid Excretion, Blood Pressure, and Metabolism in Patients With and Without CKD: The Acid Base Compensation in CKD Study. AU - Tyson,Crystal C, AU - Luciano,Alison, AU - Modliszewski,Jennifer L, AU - Corcoran,David L, AU - Bain,James R, AU - Muehlbauer,Michael, AU - Ilkayeva,Olga, AU - Pourafshar,Shirin, AU - Allen,Jenifer, AU - Bowman,Cassandra, AU - Gung,Joseph, AU - Asplin,John R, AU - Pendergast,Jane, AU - Svetkey,Laura P, AU - Lin,Pao-Hwa, AU - Scialla,Julia J, Y1 - 2021/03/31/ PY - 2020/05/03/received PY - 2020/10/10/accepted PY - 2021/4/4/pubmed PY - 2021/4/4/medline PY - 2021/4/3/entrez KW - CKD KW - NAE KW - acid-base homeostasis KW - alkali KW - bicarbonate KW - bicarbonate supplementation KW - chronic kidney disease KW - cross-over trial KW - diet KW - human feeding study KW - hypertension KW - metabolic acidosis KW - net acid excretion KW - subclinical acidosis SP - 38 EP - 47 JF - American journal of kidney diseases : the official journal of the National Kidney Foundation JO - Am J Kidney Dis VL - 78 IS - 1 N2 - 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. SN - 1523-6838 UR - https://www.unboundmedicine.com/medline/citation/33810868/Effect_of_Bicarbonate_on_Net_Acid_Excretion_Blood_Pressure_and_Metabolism_in_Patients_With_and_Without_CKD:_The_Acid_Base_Compensation_in_CKD_Study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0272-6386(20)31141-0 DB - PRIME DP - Unbound Medicine ER -