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Perut F, Graziani G, Columbaro M, Caudarella R, Baldini N, Granchi D. Citrate Supplementation Restores the Impaired Mineralisation Resulting from the Acidic Microenvironment: An In Vitro Study. Nutrients 2020; 12:E3779. [PMID: 33317151 PMCID: PMC7763163 DOI: 10.3390/nu12123779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/30/2020] [Accepted: 12/04/2020] [Indexed: 12/25/2022] Open
Abstract
Chronic metabolic acidosis leads to bone-remodelling disorders based on excessive mineral matrix resorption and inhibition of bone formation, but also affects the homeostasis of citrate, which is an essential player in maintaining the acid-base balance and in driving the mineralisation process. This study aimed to investigate the impact of acidosis on the osteogenic properties of bone-forming cells and the effects of citrate supplementation in restoring the osteogenic features impaired by the acidic milieu. For this purpose, human mesenchymal stromal cells were cultured in an osteogenic medium and the extracellular matrix mineralisation was analysed at the micro- and nano-level, both in neutral and acidic conditions and after treatment with calcium citrate and potassium citrate. The acidic milieu significantly decreased the citrate release and hindered the organisation of the extracellular matrix, but the citrate supplementation increased collagen production and, particularly calcium citrate, promoted the mineralisation process. Moreover, the positive effect of citrate supplementation was observed also in the physiological microenvironment. This in vitro study proves that the mineral matrix organisation is influenced by citrate availability in the microenvironment surrounding bone-forming cells, thus providing a biological basis for using citrate-based supplements in the management of bone-remodelling disorders related to chronic low-grade acidosis.
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Affiliation(s)
- Francesca Perut
- Biomedical Science and Technology Lab, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy; (F.P.); (N.B.)
| | - Gabriela Graziani
- Laboratory of Nanobiotechnology, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy;
| | - Marta Columbaro
- Electron Microscopy Platform, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy;
| | - Renata Caudarella
- Maria Cecilia Hospital, GVM Care and Research, Via Corriera 1, 48033 Cotignola (RA), Italy;
| | - Nicola Baldini
- Biomedical Science and Technology Lab, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy; (F.P.); (N.B.)
- Department of Biomedical and Neuromotor Sciences, Via Pupilli 1, University of Bologna, 40136 Bologna, Italy
| | - Donatella Granchi
- Biomedical Science and Technology Lab, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy; (F.P.); (N.B.)
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Raphael KL, Kraut JA. Assessing Acid-Base Status in Patients With CKD: Does Measurement of Blood pH Matter? Am J Kidney Dis 2020; 77:9-11. [PMID: 33067031 DOI: 10.1053/j.ajkd.2020.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Kalani L Raphael
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University; VA Portland Health Care System, Portland, OR.
| | - Jeffrey A Kraut
- Medical and Research Services, VHAGLA Healthcare System, Los Angeles, CA; Division of Nephrology, VHAGLA Healthcare System, Los Angeles, CA; UCLA Membrane Biology Laboratory, Los Angeles, CA; UCLA David Geffen School of Medicine Sciences, Los Angeles, CA
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53
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Spot urinary citrate-to-creatinine ratio is a marker for acid-base status in chronic kidney disease. Kidney Int 2020; 99:208-217. [PMID: 32721446 DOI: 10.1016/j.kint.2020.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 11/20/2022]
Abstract
Due to multiple compensating mechanisms, the serum bicarbonate concentration is a relatively insensitive marker of acid-base status; especially in chronic kidney disease (CKD). This is a major drawback that impairs the ability to diagnose acid excess or monitor alkali therapy. We postulated that it is more logical to measure the compensatory defense mechanism(s) rather than the defended parameter, which remains normal if the compensation is successful. Therefore, a retrospective cross-sectional study was performed in 1733 stone formers along with a prospective cross-sectional study of 22 individuals with normal kidney function and 50 patients in different stages of CKD. While serum bicarbonate was flat and did not fall below the reference range until near CKD stage 5, citrate excretion (24-hour urinary citrate excretion rate; urinary citrate-to-creatinine ratio, in the retrospective analysis, and spot urinary citrate-to-creatinine ratio in the prospective study) progressively and significantly declined starting from CKD stage 2. Following an acute acid load in 25 participants with a wide range of estimated glomerular filtration rates, the urinary citrate-to-creatinine ratio inversely and significantly associated with acid accumulation, whereas serum bicarbonate did not. We compared changes in serum bicarbonate and urinary citrate-to-creatinine ratio in response to alkali therapy in patients with CKD stage 3 or 4 started on potassium citrate in our kidney stone database. With alkali therapy, there was no change in serum bicarbonate, but the urinary citrate-to-creatinine ratio rose consistently in all patients adherent to potassium citrate therapy. Thus, the urinary citrate-to-creatinine ratio (the defense mechanism) is a potential easily implementable, pragmatic, and a superior parameter to serum bicarbonate (the defended entity) to assess acid-base status, and monitor alkali therapy. Additional studies are needed before a clinical test can be devised.
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Abstract
PURPOSE OF REVIEW Both chronic kidney disease (CKD) and kidney stones are major public health problems, which are closely interrelated. Recurrent kidney stones predispose to CKD although CKD seems to decrease risk of further kidney stone formation. Herein, we review new information of this interrelationship. RECENT FINDINGS Several epidemiological studies in the past have shown an association between history of kidney stones and risk for CKD and CKD progression. Recent literature supports this concept and it is reviewed in this article. The issue of whether CKD protects against new kidney stone formation remains unsettled and there is no recent literature addressing it. In relation to stone risk factors in CKD, there are several interesting new articles that discuss mechanisms of hypocitraturia in early CKD before overt metabolic acidosis. Since hypocitraturia is an important risk factor for kidney stone formation we addressed these new data in detail. There are also new data supporting urinary oxalate excretion as a predictor of CKD progression. SUMMARY It seems clear that recurrent kidney stones should be avoided not only because of their immediate clinical manifestations but also because of their long-term predisposition to CKD progression. Mechanisms leading to hypocitraturia in early CKD still remain controversial.
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Szeri F, Lundkvist S, Donnelly S, Engelke UFH, Rhee K, Williams CJ, Sundberg JP, Wevers RA, Tomlinson RE, Jansen RS, van de Wetering K. The membrane protein ANKH is crucial for bone mechanical performance by mediating cellular export of citrate and ATP. PLoS Genet 2020; 16:e1008884. [PMID: 32639996 PMCID: PMC7371198 DOI: 10.1371/journal.pgen.1008884] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/20/2020] [Accepted: 05/25/2020] [Indexed: 01/23/2023] Open
Abstract
The membrane protein ANKH was known to prevent pathological mineralization of joints and was thought to export pyrophosphate (PPi) from cells. This did not explain, however, the presence of ANKH in tissues, such as brain, blood vessels and muscle. We now report that in cultured cells ANKH exports ATP, rather than PPi, and, unexpectedly, also citrate as a prominent metabolite. The extracellular ATP is rapidly converted into PPi, explaining the role of ANKH in preventing ankylosis. Mice lacking functional Ank (Ankank/ank mice) had plasma citrate concentrations that were 65% lower than those detected in wild type control animals. Consequently, citrate excretion via the urine was substantially reduced in Ankank/ank mice. Citrate was even undetectable in the urine of a human patient lacking functional ANKH. The hydroxyapatite of Ankank/ank mice contained dramatically reduced levels of both, citrate and PPi and displayed diminished strength. Our results show that ANKH is a critical contributor to extracellular citrate and PPi homeostasis and profoundly affects bone matrix composition and, consequently, bone quality.
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Affiliation(s)
- Flora Szeri
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Stefan Lundkvist
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Sylvia Donnelly
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Udo F. H. Engelke
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kyu Rhee
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Charlene J. Williams
- Cooper Medical School of Rowan University, Camden, New Jersey, United States of America
| | - John P. Sundberg
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Ron A. Wevers
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ryan E. Tomlinson
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Robert S. Jansen
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Wesson DE, Buysse JM, Bushinsky DA. Mechanisms of Metabolic Acidosis-Induced Kidney Injury in Chronic Kidney Disease. J Am Soc Nephrol 2020; 31:469-482. [PMID: 31988269 DOI: 10.1681/asn.2019070677] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Retrospective analyses and single-center prospective studies identify chronic metabolic acidosis as an independent and modifiable risk factor for progression of CKD. In patients with CKD, untreated chronic metabolic acidosis often leads to an accelerated reduction in GFR. Mechanisms responsible for this reduction include adaptive responses that increase acid excretion but lead to a decline in kidney function. Metabolic acidosis in CKD stimulates production of intrakidney paracrine hormones including angiotensin II, aldosterone, and endothelin-1 (ET-1) that mediate the immediate benefit of increased kidney acid excretion, but their chronic upregulation promotes inflammation and fibrosis. Chronic metabolic acidosis also stimulates ammoniagenesis that increases acid excretion but also leads to ammonia-induced complement activation and deposition of C3 and C5b-9 that can cause tubule-interstitial damage, further worsening disease progression. These effects, along with acid accumulation in kidney tissue, combine to accelerate progression of kidney disease. Treatment of chronic metabolic acidosis attenuates these adaptive responses; reduces levels of angiotensin II, aldosterone, and ET-1; reduces ammoniagenesis; and diminishes inflammation and fibrosis that may lead to slowing of CKD progression.
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Affiliation(s)
- Donald E Wesson
- Baylor Scott & White Health and Wellness Center, Dallas, Texas; .,Department of Internal Medicine, Texas A&M College of Medicine, Bryan, Texas
| | | | - David A Bushinsky
- Division of Nephrology, University of Rochester School of Medicine, Rochester, New York
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Successful correction of metabolic acidosis is difficult to achieve in chronic kidney disease. Nefrologia 2019; 40:328-335. [PMID: 31862183 DOI: 10.1016/j.nefro.2019.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/13/2019] [Accepted: 09/16/2019] [Indexed: 11/20/2022] Open
Abstract
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.
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Melamed ML, Horwitz EJ, Dobre MA, Abramowitz MK, Zhang L, Lo Y, Mitch WE, Hostetter TH. Effects of Sodium Bicarbonate in CKD Stages 3 and 4: A Randomized, Placebo-Controlled, Multicenter Clinical Trial. Am J Kidney Dis 2019; 75:225-234. [PMID: 31699517 DOI: 10.1053/j.ajkd.2019.07.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 07/16/2019] [Indexed: 01/18/2023]
Abstract
RATIONALE & OBJECTIVE Metabolic acidosis associated with chronic kidney disease (CKD) may contribute to muscle dysfunction and bone disease. We aimed to test whether treatment with sodium bicarbonate improves muscle and bone outcomes. STUDY DESIGN Multicenter, randomized, placebo-controlled, clinical trial. SETTING & PARTICIPANTS 149 patients with CKD stages 3 and 4 between July 2011 and April 2016 at 3 centers in Cleveland, OH, and the Bronx, NY. INTERVENTION Sodium bicarbonate (0.4 mEq per kg of ideal body weight per day) (n=74) or identical-appearing placebo (n=75). OUTCOMES Dual primary outcomes were muscle function assessed using sit-to-stand test and bone mineral density. Muscle biopsies were performed at baseline and 2 months. Participants were seen at baseline and 2, 6, 12, and 24 months. RESULTS Mean baseline serum bicarbonate level was 24.0±2.2 (SD) mEq/L and mean baseline estimated glomerular filtration rate was 36.3±11.2mL/min/1.73m2. Baseline characteristics did not differ between groups. Mean serum bicarbonate levels in the intervention arm during follow-up were 26.4±2.2, 25.5±2.3, 25.6±2.6, and 24.4±2.8 mEq/L (at 2, 6, 12, and 24 months). These were significantly higher than in the placebo group (P<0.001). Compared to the placebo group, participants randomly assigned to sodium bicarbonate treatment had no significant differences in sit-to-stand time (5 repetitions: P=0.1; and 10 repetitions P=0.07) or bone mineral density (P=0.3). Sodium bicarbonate treatment caused a decrease in serum potassium levels that was of borderline statistical significance (P=0.05). There were no significant differences in estimated glomerular filtration rates, blood pressure, weight, serious adverse events, or levels of muscle gene expression between the randomly assigned groups. LIMITATIONS Initial mean serum bicarbonate level was in the normal range. CONCLUSIONS Sodium bicarbonate therapy in patients with CKD stages 3 and 4 significantly increases serum bicarbonate and decreases potassium levels. No differences were found in muscle function or bone mineral density between the randomly assigned groups. Larger trials are required to evaluate effects on kidney function. FUNDING National Institutes of Health grant. TRIAL REGISTRATION Registered at ClinicalTrials.gov with study number NCT01452412.
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Affiliation(s)
- Michal L Melamed
- Department of Medicine (Nephrology), Albert Einstein College of Medicine/ Montefiore Medical Center, Bronx, NY; Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY.
| | - Edward J Horwitz
- Department of Medicine (Nephrology), MetroHealth Medical Center, Cleveland, OH
| | - Mirela A Dobre
- Department of Medicine (Nephrology), Case Western Reserve University/University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Matthew K Abramowitz
- Department of Medicine (Nephrology), Albert Einstein College of Medicine/ Montefiore Medical Center, Bronx, NY
| | - Liping Zhang
- Department of Medicine (Nephrology), Baylor College of Medicine, Houston, TX
| | - Yungtai Lo
- Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY
| | - William E Mitch
- Department of Medicine (Nephrology), Baylor College of Medicine, Houston, TX
| | - Thomas H Hostetter
- Department of Medicine (Nephrology), Case Western Reserve University/University Hospitals Cleveland Medical Center, Cleveland, OH
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Prot-Bertoye C, Vallet M, Houillier P. Urinary citrate: helpful to predict acid retention in CKD patients? Kidney Int 2019; 95:1020-1022. [PMID: 31010475 DOI: 10.1016/j.kint.2019.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 01/24/2019] [Accepted: 01/31/2019] [Indexed: 10/27/2022]
Abstract
Acid retention occurs early during the course of chronic kidney disease (CKD). Studies conducted in patients with CKD suggest that alkali supplementation may slow CKD progression. However, the diagnosis of acid retention is challenging when plasma bicarbonate concentration is still normal. In this issue, Goraya et al. suggest that urinary citrate may predict acid retention in eubicarbonatemic patients with stages 1 and 2 CKD . Although interesting, this claim yet requires confirmation by further studies.
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Affiliation(s)
- Caroline Prot-Bertoye
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France; CNRS, ERL 8228, Paris, France; Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France; Université Paris Descartes, Paris, France
| | - Marion Vallet
- Service des Explorations Fonctionnelles Physiologiques, CHU de Toulouse, Toulouse, France
| | - Pascal Houillier
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France; CNRS, ERL 8228, Paris, France; Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France; Université Paris Descartes, Paris, France.
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60
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Granchi D, Baldini N, Ulivieri FM, Caudarella R. Role of Citrate in Pathophysiology and Medical Management of Bone Diseases. Nutrients 2019; 11:E2576. [PMID: 31731473 PMCID: PMC6893553 DOI: 10.3390/nu11112576] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/19/2019] [Accepted: 10/22/2019] [Indexed: 12/11/2022] Open
Abstract
Citrate is an intermediate in the "Tricarboxylic Acid Cycle" and is used by all aerobic organisms to produce usable chemical energy. It is a derivative of citric acid, a weak organic acid which can be introduced with diet since it naturally exists in a variety of fruits and vegetables, and can be consumed as a dietary supplement. The close association between this compound and bone was pointed out for the first time by Dickens in 1941, who showed that approximately 90% of the citrate bulk of the human body resides in mineralised tissues. Since then, the number of published articles has increased exponentially, and considerable progress in understanding how citrate is involved in bone metabolism has been made. This review summarises current knowledge regarding the role of citrate in the pathophysiology and medical management of bone disorders.
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Affiliation(s)
- Donatella Granchi
- Laboratory for Orthopedic Pathophysiology and Regenerative Medicine, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy;
| | - Nicola Baldini
- Laboratory for Orthopedic Pathophysiology and Regenerative Medicine, IRCCS Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy;
- Department of Biomedical and Neuromotor Sciences, Via Pupilli 1, University of Bologna, 40136 Bologna, Italy
| | - Fabio Massimo Ulivieri
- Nuclear Medicine, Bone Metabolic Unit, IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Via F.Sforza 35, 20122 Milano, Italy;
| | - Renata Caudarella
- Maria Cecilia Hospital, GVM Care and Research, Via Corriera 1, 48033 Cotignola (RA), Italy;
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61
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Goraya N, Simoni J, Sager LN, Mamun A, Madias NE, Wesson DE. Urine citrate excretion identifies changes in acid retention as eGFR declines in patients with chronic kidney disease. Am J Physiol Renal Physiol 2019; 317:F502-F511. [PMID: 31215805 DOI: 10.1152/ajprenal.00044.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Previous studies have shown that acid (H+) retention in patients with chronic kidney disease (CKD) but without metabolic acidosis increases as the estimated glomerular filtration rate (eGFR) decreases over time. The present study examined whether changes in urine excretion of the pH-sensitive metabolite citrate predicted changes in H+ retention over time in similar patients with CKD that were followed for 10 yr. We randomized 120 CKD2 nondiabetic, hypertension-associated nephropathy patients with plasma total CO2 of >24 mM to receive 0.5 meq·kg body wt-1·day-1 NaHCO3 ([Formula: see text]; n = 40), 0.5 meq·kg body wt-1·day-1 NaCl (NaCl; n = 40), or usual care (UC; n = 40). We assessed eGFR (CKD-EPI) and H+ retention by comparing the observed with expected plasma total CO2 increase 2 h after an oral NaHCO3 bolus (0.5 meq/kg body wt). Although 10 yr versus baseline eGFR was lower for each group, 10-yr eGFR was higher (P < 0.01) in [Formula: see text] (59.6 ± 4.8 ml·min-1·1.73 m-2) than NaCl and UC (52.1 ± 5.9 and 52.3 ± 4.1 ml·min-1·1.73 m-2, respectively) groups. Less eGFR preservation was associated with higher 10-yr versus baseline H+ retention in the NaCl group (26.5 ± 13.1 vs. 18.2 ± 15.3 mmol, P < 0.01) and UC group (24.8 ± 11.3 vs. 17.7 ± 10.9 mmol, P < 0.01) and with lower 10-yr versus baseline 8-h urine citrate excretion (UcitrateV) for the NaCl group (162 ± 47 vs. 196 ± 52 mg, respectively, P < 0.01) and UC group (153 ± 41 vs. 186 ± 42 mg, respectively, P < 0.01). Conversely, better eGFR preservation in the [Formula: see text] group was associated with no differences in 10-yr versus baseline H+ retention (14.2 ±13.5 vs. 16.1 ± 15.1 mmol, P = 1.00) or UcitrateV (212 ± 45 vs. 203 ± 49 mg, respectively, P = 0.74). An overall generalized linear model for repeated measures showed that UcitrateV predicted H+ retention (P < 0.01). Less eGFR preservation in patients with CKD2 without metabolic acidosis was associated with increased H+ retention that was predicted by decreased UcitrateV.
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Affiliation(s)
- Nimrit Goraya
- Baylor Scott and White Health Department of Internal Medicine, Temple, Texas.,Texas A&M Health Sciences Center, College of Medicine, Temple Texas
| | - Jan Simoni
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Lauren N Sager
- Baylor Scott and White Health Department of Biostatistics, Temple, Texas
| | - Abdullah Mamun
- Baylor Scott and White Health and Wellness Center, Dallas, Texas
| | - Nicolaos E Madias
- School of Medicine, Department of Medicine, St. Elizabeth's Medical Center and Tufts University, Boston, Massachusetts
| | - Donald E Wesson
- Baylor Scott and White Health Department of Internal Medicine, Dallas, Texas.,Texas A&M Health Sciences Center, College of Medicine, Dallas, Texas
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