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Wen S, Arakawa H, Tamai I. Uric acid in health and disease: From physiological functions to pathogenic mechanisms. Pharmacol Ther 2024; 256:108615. [PMID: 38382882 DOI: 10.1016/j.pharmthera.2024.108615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/02/2024] [Accepted: 02/17/2024] [Indexed: 02/23/2024]
Abstract
Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.
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Affiliation(s)
- Shijie Wen
- Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Hiroshi Arakawa
- Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Ikumi Tamai
- Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
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Anders HJ, Li Q, Steiger S. Asymptomatic hyperuricaemia in chronic kidney disease: mechanisms and clinical implications. Clin Kidney J 2023; 16:928-938. [PMID: 37261000 PMCID: PMC10229286 DOI: 10.1093/ckj/sfad006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Indexed: 10/19/2023] Open
Abstract
Asymptomatic hyperuricaemia (HU) is considered a pathogenic factor in multiple disease contexts, but a causative role is only proven for the crystalline form of uric acid in gouty arthritis and urate nephropathy. Epidemiological studies document a robust association of HU with hypertension, cardiovascular disease (CVD) and CKD progression, but CKD-related impaired uric acid (UA) clearance and the use of diuretics that further impair UA clearance likely accounts for these associations. Interpreting the available trial evidence is further complicated by referring to xanthine oxidase inhibitors as urate-lowering treatment, although these drugs inhibit other substrates, so attributing their effects only to HU is problematic. In this review we provide new mechanistic insights into the biological effects of soluble and crystalline UA and discuss clinical evidence on the role of asymptomatic HU in CKD, CVD and sterile inflammation. We identify research areas with gaps in experimental and clinical evidence, specifically on infectious complications that represent the second common cause of death in CKD patients, referred to as secondary immunodeficiency related to kidney disease. In addition, we address potential therapeutic approaches on how and when to treat asymptomatic HU in patients with kidney disease and where further interventional studies are required.
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Affiliation(s)
- Hans-Joachim Anders
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilians University, Munich, Germany
| | - Qiubo Li
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilians University, Munich, Germany
| | - Stefanie Steiger
- Division of Nephrology, Department of Medicine IV, Hospital of the Ludwig-Maximilians University, Munich, Germany
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3
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Siener R, Löhr P, Hesse A. Urinary Risk Profile, Impact of Diet, and Risk of Calcium Oxalate Urolithiasis in Idiopathic Uric Acid Stone Disease. Nutrients 2023; 15:nu15030572. [PMID: 36771279 PMCID: PMC9919786 DOI: 10.3390/nu15030572] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
The role of diet in the pathogenesis of uric acid (UA) nephrolithiasis is incompletely understood. This study investigated the effect of dietary intervention on the risk of UA stone formation under standardized conditions. Twenty patients with idiopathic UA stone disease were included in the study. Dietary intake and 24 h urinary parameters were collected on the usual diet of the patients and a standardized balanced mixed diet. Although urinary UA excretion did not change, the relative supersaturation of UA decreased significantly by 47% under the balanced diet primarily due to the significant increase in urine volume and pH. Urinary pH was below 5.8 in 85% of patients under the usual diet, and in 60% of patients under the balanced diet. The supersaturation of calcium oxalate declined significantly under the balanced diet due to the significant decrease in urinary calcium and oxalate excretion and the increase in urine volume. Dietary intervention is a key component in the management of UA nephrolithiasis. Urinary calcium and oxalate excretion should also be monitored in patients with pure UA calculi to reduce the risk of mixed stone formation with calcium oxalate. Lower urinary pH in UA stone patients can only be partially explained by diet.
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Uribarri J, Goldfarb DS, Raphael KL, Rein JL, Asplin JR. Beyond the Urine Anion Gap: In Support of the Direct Measurement of Urinary Ammonium. Am J Kidney Dis 2022; 80:667-676. [PMID: 35810828 DOI: 10.1053/j.ajkd.2022.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/10/2022] [Indexed: 02/02/2023]
Abstract
Ammonium is a major urinary buffer that is necessary for the normal excretion of the daily acid load. Its urinary rate of excretion (UNH4) may be increased several fold in the presence of extrarenal metabolic acidosis. Therefore, measurement of UNH4 can provide important clues about causes of metabolic acidosis. Because UNH4 is not commonly measured in clinical laboratories, the urinary anion gap (UAG) was proposed as its surrogate about 4 decades ago, and it is still frequently used for that purpose. Several published studies strongly suggest that UAG is not a good index of UNH4 and support the concept that direct measurement of UNH4 is an important parameter to define in clinical nephrology. Low UNH4 levels have recently been found to be associated with a higher risk of metabolic acidosis, loss of kidney function, and death in persons with chronic kidney disease, while surrogates like the UAG do not recapitulate this risk. In order to advance the field it is necessary for the medical community to become more familiar with UNH4 levels in a variety of clinical settings. Herein, we review the literature, searching for available data on UNH4 under normal and various pathological conditions, in an attempt to establish reference values to interpret UNH4 results if and when UNH4 measurements become available as a routine clinical test. In addition, we present original data in 2 large populations that provide further evidence that the UAG is not a good predictor of UNH4. Measurement of urine NH4 holds promise to aid clinicians in the care of patients, and we encourage further research to determine its best diagnostic usage.
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Affiliation(s)
- Jaime Uribarri
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
| | | | - Kalani L Raphael
- Oregon Health & Science University and VA Portland Health Care System, Portland, Oregon
| | - Joshua L Rein
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, Illinois
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Hood VL, Sternberg KM, de Waal D, Asplin JR, Mulligan C, Callas PW. Association of Urine Findings with Metabolic Syndrome Traits in a Population of Patients with Nephrolithiasis. KIDNEY360 2021; 3:317-324. [PMID: 35373120 PMCID: PMC8967639 DOI: 10.34067/kid.0002292021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 11/23/2021] [Indexed: 01/10/2023]
Abstract
Background The odds of nephrolithiasis increase with more metabolic syndrome (MetS) traits. We evaluated associations of metabolic and dietary factors from urine studies and stone composition with MetS traits in a large cohort of stone-forming patients. Methods Patients >18 years old who were evaluated for stones with 24-hour urine collections between July 2009 and December 2018 had their records reviewed retrospectively. Patient factors, laboratory values, and diagnoses were identified within 6 months of urine collection and stone composition within 1 year. Four groups with none, one, two, and three or four MetS traits (hypertension, obesity, dyslipidemia, and diabetes) were evaluated. Trends across groups were tested using linear contrasts in analysis of variance and analysis of covariance. Results A total of 1473 patients met the inclusion criteria (835 with stone composition). MetS groups were 684 with no traits, 425 with one trait, 211 with two traits, and 153 with three or four traits. There were no differences among groups for urine volume, calcium, or ammonium excretion. There was a significant trend (P<0.001) for more MetS traits being associated with decreasing urine pH, increasing age, calculated dietary protein, urine uric acid (UA), oxalate, citrate, titratable acid phosphate, net acid excretion, and UA supersaturation. The ratio of ammonium to net acid excretion did not differ among the groups. After adjustment for protein intake, the fall in urine pH remained strong, while the upward trend in acid excretion was lost. Calcium oxalate stones were most common, but there was a trend for more UA (P<0.001) and fewer calcium phosphate (P=0.09) and calcium oxalate stones (P=0.01) with more MetS traits. Conclusions Stone-forming patients with MetS have a defined pattern of metabolic and dietary risk factors that contribute to an increased risk of stone formation, including higher acid excretion, largely the result of greater protein intake, and lower urine pH.
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Affiliation(s)
- Virginia L. Hood
- Department of Nephrology, University of Vermont Medical Center, Burlington, Vermont
| | - Kevan M. Sternberg
- Department of Urology, University of Vermont Medical Center, Burlington, Vermont
| | - Desiree de Waal
- Department of Nephrology, University of Vermont Medical Center, Burlington, Vermont
| | - John R. Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Itasca, Illinois
| | - Carley Mulligan
- Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Peter W. Callas
- Medical Biostatistics, University of Vermont, Burlington, Vermont
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Association between aortic calcification and the presence of kidney stones: calcium oxalate calculi in focus. Int Urol Nephrol 2021; 54:1915-1923. [PMID: 34846621 PMCID: PMC9262773 DOI: 10.1007/s11255-021-03058-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/11/2021] [Indexed: 02/05/2023]
Abstract
PURPOSE The current research is aimed at analyzing the relationship between kidney stone (KS) and abdominal aortic calcification (AAC) and the relationship between KS components and AAC. METHODS This is a retrospective, case-control study. Kidney stone formers (KSFs) were treated at the Department of Urology, West China Hospital, Sichuan University for urological calculus disease from January 2014 to January 2020. Matched non-stone formers (non-SFs) were drawn from the same hospital for routine health examination from January 2018 to February 2019. Research-related information was collected and reviewed retrospectively from the hospital's computerized records. AAC were evaluated using available results of computed tomography imaging and abdominal vascular ultrasound. The relationships of AAC between KSFs and non-SFs were compared. The composition of renal calculi was analyzed by Fourier-transform infrared spectrophotometer. KSFs were divided into AAC groups and non-AAC based on AAC. The relationship of the composition of renal calculi between AAC and non-AAC were compared. The independent-sample t test, the chi-squared test and binary logistics regression were performed. RESULTS Altogether, 4516 people were included, with 1027 KSFs and 3489 non-SFs. There were no significant differences in the laboratory parameters between KSFs and non-SFs. The association between the presence of AAC and KS was significant in multivariable model 2 [adjusting hypertension, diabetes mellitus, fasting blood glucose, uric acid, serum triglyceride (TG), serum calcium, and urine pH] (OR 5.756, 95% CI 4.616-7.177, p < 0.001). The result of KSFs showed that calcium oxalate calculi (CaOx) was significantly associated with AAC in multivariable model 3 (adjusting age, hypertension, diabetes mellitus, drinking history, smoking history, and TG) (OR 1.351, 95% CI 1.002-1.822, p = 0.048). CONCLUSIONS The current study pioneered the revelation of the relationship between CaOx and AAC. Through an elimination of the confounding factors, the study demonstrated that KS and AAC were connected.
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Bohling R, Grafals M, Moreau K, You Z, Tommerdahl KL, Bjornstad P, Stenson EK, Andrews E, Ramirez-Renteria L, Kendrick J. A Pilot Study of the Safety and Efficacy of Alkali Therapy on Vascular Function in Kidney Transplant Recipients. Kidney Int Rep 2021; 6:2323-2330. [PMID: 34514193 PMCID: PMC8419116 DOI: 10.1016/j.ekir.2021.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/18/2021] [Accepted: 06/07/2021] [Indexed: 12/31/2022] Open
Abstract
Introduction Metabolic acidosis is associated with cardiovascular events, graft function, and mortality in kidney transplant recipients (KTRs). We examined the effect of alkali therapy on vascular endothelial function in KTRs. Methods We performed an 18-week, randomized, double-blind, placebo-controlled crossover pilot study examining the effect of sodium bicarbonate therapy versus placebo on vascular function in 20 adult KTRs at least 1 year from transplant with an estimated glomerular filtration rate (eGFR) ≥45 ml/min per 1.73 m2 and a serum bicarbonate level of 20 to 26 mEq/L. Each treatment period was 8 weeks in duration with a 2-week washout period between treatments. The primary outcome was change in brachial artery flow-mediated dilation (FMD) between sodium bicarbonate treatment and placebo. Results Twenty patients completed the study and were included in the primary analysis. The mean (SD) baseline eGFR of participants was 75 (22) ml/min per 1.73 m2, respectively. Serum bicarbonate levels did not increase significantly with treatment (0.3 [1.5] mEq/L, P = 0.37). Sodium bicarbonate therapy was not associated with worsening blood pressure, weight gain, or hypokalemia. There was no significant increase in FMD after 8 weeks of sodium bicarbonate therapy compared to placebo (mean change in FMD 2.2%, 95% CI -0.1 to 4.6, P = 0.06). There were no significant changes in high-sensitivity C-reactive protein, interleukin-6, eGFR, or urinary albumin-to-creatinine ratio during treatment. Urinary ammonium excretion decreased by 9 mmol/d (P=0.003), with sodium bicarbonate. Conclusions Sodium bicarbonate therapy is safe and feasible in KTRs, and our results strengthen the need for a larger randomized controlled trial.
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Affiliation(s)
- Rachel Bohling
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Monica Grafals
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kerrie Moreau
- Division of Geriatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.,Eastern Colorado VA Geriatric Research, Education and Clinical Center, Aurora, Colorado, USA
| | - Zhiying You
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kalie L Tommerdahl
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.,Department of Pediatrics, Section of Pediatric Endocrinology, Children's Hospital Colorado and University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Petter Bjornstad
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.,Department of Pediatrics, Section of Pediatric Endocrinology, Children's Hospital Colorado and University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Erin K Stenson
- Department of Pediatrics, Section of Critical Care Medicine, Children's Hospital Colorado and University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Emily Andrews
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Lorena Ramirez-Renteria
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jessica Kendrick
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Kawaguchi S, Fujiwara SI, Murahashi R, Nakashima H, Matsuoka S, Ikeda T, Toda Y, Ito S, Ban T, Nagayama T, Umino K, Minakata D, Nakano H, Yamasaki R, Ashizawa M, Yamamoto C, Hatano K, Sato K, Oh I, Ohmine K, Kanda Y. Risk factors for high-dose methotrexate-induced nephrotoxicity. Int J Hematol 2021; 114:79-84. [PMID: 33743109 DOI: 10.1007/s12185-021-03132-8] [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: 10/15/2020] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 12/01/2022]
Abstract
High-dose methotrexate (MTX) is widely used for the treatment of hematological malignancies. Despite the application of routine supportive care measures, such as intensive fluid hydration and urine alkalinization, nephrotoxicity is still a problem. The present study aimed to evaluate the risk factors for MTX-induced nephrotoxicity. We retrospectively reviewed 88 patients who received a regimen consisting of high-dose MTX (1000 mg/m2) and cytosine arabinoside between 2006 and 2018. Nephrotoxicity (≥ grade 2) was observed in 11 patients. Nephrotoxicity was observed only in patients with a high MTX concentration. Other than the MTX concentration, the serum uric acid level and urine pH at day 1 were associated with nephrotoxicity. A multivariate analysis revealed that urine pH was an independent risk factor for MTX-induced nephrotoxicity. Urine pH < 7.0 at day 1 was a significant risk factor for nephrotoxicity (odds ratio, 8.05; 95% confidence interval 1.95-33.3) and was also a predictor of delayed MTX elimination at 72 h after injection. Among pre-treatment factors, a low serum calcium level predicted urine pH < 7.0 at day 1. In conclusion, the present study suggests that low urine pH at day 1 is an independent risk factor for MTX-induced nephrotoxicity.
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Affiliation(s)
- Shinichiro Kawaguchi
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Shin-Ichiro Fujiwara
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan.,Division of Cell Transplantation and Transfusion, Jichi Medical University Hospital, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Rui Murahashi
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Hirotomo Nakashima
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Sae Matsuoka
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Takashi Ikeda
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Yumiko Toda
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Shoko Ito
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Tetsuaki Ban
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Takashi Nagayama
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Kento Umino
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Daisuke Minakata
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Hirofumi Nakano
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Ryoko Yamasaki
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Masahiro Ashizawa
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Chihiro Yamamoto
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Kaoru Hatano
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Kazuya Sato
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Iekuni Oh
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Ken Ohmine
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Yoshinobu Kanda
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan.
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Huo J, Li D, McKay C, Hoke M, Worcester E, Coe F. Relative contributions of urine sulfate, titratable urine anion, and GI anion to net acid load and effects of age. Physiol Rep 2021; 9:e14870. [PMID: 34042292 PMCID: PMC8157790 DOI: 10.14814/phy2.14870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 11/24/2022] Open
Abstract
Models of acid–base balance include acid production from (1) oxidation of sulfur atoms on amino acids and (2) metabolically produced organic acid anions. Acid load is balanced by alkali from metabolism of GI anions; thus, net acid production is equivalent to the sum of urine sulfate and organic anion (measured by titration in urine), minus GI anion. However, the relative contributions of these three sources of acid production in people eating free choice diets, and presumably in acid–base balance, have not been well studied. We collected 26 urines from 18 normal subjects (10 male) and 43 urine samples from 34 stone formers (17 male) and measured sulfate, organic anion, and components of GI anion and acid excretion in each; values were expressed as mEq/mmol creatinine. Mean values of the urine components, except creatinine and pH, did not differ between the sexes or groups. Urine organic acid and acid production varied directly with age (p ≤ 0.03). In a general linear model of acid excretion, the coefficients for sulfate, organic anion, and GI anion were 0.34 ± 0.09, 0.49 ± 0.12, and −0.51 ± 0.06, respectively, p ≤ 0.005, and the model accounted for 54% of the variance. A model for urine ammonia gave similar results. Urine organic anion is a significant contributor to total acid production and may be responsible for an increase in acid production with age.
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Affiliation(s)
- Jenny Huo
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
| | - Daniel Li
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
| | - Charles McKay
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
| | - Madeleine Hoke
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
| | - Elaine Worcester
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
| | - Fredric Coe
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois, USA
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10
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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: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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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11
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Shevel E. Conditions Favoring Increased COVID-19 Morbidity and Mortality: Their Common Denominator and its Early Treatment. MISSOURI MEDICINE 2021; 118:113-115. [PMID: 33840847 PMCID: PMC8029622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The factors contributing to increased morbidity and mortality in SARS-CoV-2 infection are diverse, and include diabetes, obesity, Chronic Obstructive Pulmonary Disease (COPD), advanced age, and male sex. Although there is no obvious connection between these, they do have one common denominator-they all have a tendency towards lower urine pH, which may indicate a lower-than-normal tissue pH. Furthermore, it has been shown that lower pH has two important negative influences: 1) it enhances viral fusion via the endosomal route, thereby facilitating viral multiplication; and 2) it facilitates increased production of inflammatory cytokines, thereby exacerbating the cytokine storm. This paper discusses published literature on lower tissue/interstitial pH in those diseases/co-morbidities that are known risk factors of severe COVID-19, and hypothesize that small doses of baking soda could be a simple, cost-effective, and rapid method of reducing both morbidity and mortality in COVID-19 patients.
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Affiliation(s)
- Eliot Shevel
- Head of the South African Headache Society, the South African affiliate of the International Headache Society. He is founder and practices at The Headache Clinic in Johannesburg, South Africa
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12
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Tran TVM, Li X, Adams-Huet B, Maalouf NM. Impact of age and renal function on urine chemistry in patients with calcium oxalate kidney stones. Urolithiasis 2021; 49:495-504. [PMID: 33582830 DOI: 10.1007/s00240-021-01254-6] [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: 09/24/2020] [Accepted: 01/30/2021] [Indexed: 12/22/2022]
Abstract
Nephrolithiasis is associated with an increased risk of chronic kidney disease, and its incidence varies with age. However, little is known on the combined impact of aging and declining renal function on urinary risk factors for calcium oxalate stone formation. A retrospective analysis was performed on 24-h urine collections from 993 calcium oxalate stone-forming patients. We first tested for interactions between age and creatinine clearance on various urinary determinants of calcium oxalate nephrolithiasis, and then examined their separate and combined effects in univariable and multivariable analyses adjusting for demographic and biochemical covariates. We identified significant interactions between age and creatinine clearance in predicting 24-h urine pH, calcium, and citrate. In view of the small number of stone formers with low creatinine clearance, we limited further regression analyses to patients with creatinine clearance ≥ 60 mL/min. In multivariable analyses, urine citrate, oxalate, and total volume were positively correlated with age, whereas urine pH, citrate, calcium, oxalate, total volume, and RSR of calcium oxalate all significantly decreased with lower creatinine clearance. A decrease in creatinine clearance from 120 to 60 mL/min was associated with clinically significant decreases in the daily excretion rate of citrate (by 188 mg/day), calcium (by 33 mg/day), and oxalate (by 4 mg/day), and in RSR calcium oxalate (by 1.84). Age and creatinine clearance are significant and independent predictors of several urinary determinants of calcium oxalate nephrolithiasis. The impacts of aging and declining renal function should be considered during the management of calcium oxalate stone-forming patients.
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Affiliation(s)
- Triet Vincent M Tran
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-8885, USA
| | - Xilong Li
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-8885, USA.,Department of Population and Data Sciences, UT Southwestern Medical Center, Dallas, TX, USA
| | - Beverley Adams-Huet
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-8885, USA.,Department of Population and Data Sciences, UT Southwestern Medical Center, Dallas, TX, USA
| | - Naim M Maalouf
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-8885, USA. .,Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA.
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13
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Abstract
PURPOSE OF REVIEW An overly acidic urine resulting in supersaturation of urine with respect to uric acid is the major mechanism responsible for uric acid nephrolithiasis. The present review summarizes findings from recent human physiologic studies examining the pathophysiology and reversibility of low urine pH in uric acid stone formers. RECENT FINDINGS Epidemiologic and metabolic studies have confirmed an increase in the prevalence of uric acid nephrolithiasis and reported its association with several features of the metabolic syndrome including dyslipidemia, hyperglycemia, hepatic steatosis, and greater visceral adiposity. Physiologic studies in uric acid stone formers have identified diet-independent excessive net acid excretion and concomitant reduction in urinary buffering from impaired renal ammoniagenesis as the two causes underlying the greater aciduria. Administration of the insulin sensitizer pioglitazone to uric acid stone formers reduced the acid load presented to the kidney and enhanced ammoniagenesis and ammonium excretion, resulting in significantly higher urine pH. SUMMARY Recent human physiologic studies have identified greater acid excretion and reduced urinary buffering by ammonia as two culprits of aciduria in uric acid nephrolithiasis that can be reversed by pioglitazone, raising new questions regarding the origin of the aciduria and opening the door to pathophysiology-based treatment of uric acid stones.
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14
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Zhao Y, Yang L. Twenty-four-hour urine osmolality should be used in combination with other urine parameters in urolithiasis patients. Int Urol Nephrol 2019; 51:1357-1358. [PMID: 31201664 DOI: 10.1007/s11255-019-02198-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 02/05/2023]
Affiliation(s)
- Yuliang Zhao
- Division of Nephrology, West China Hospital of Sichuan University, 37# Guoxue Alley, Wuhou District, Chengdu, 610041, Sichuan, China. .,Kidney Research Laboratory, National Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, 610041, Sichuan, China.
| | - Letian Yang
- Division of Nephrology, West China Hospital of Sichuan University, 37# Guoxue Alley, Wuhou District, Chengdu, 610041, Sichuan, China.,Kidney Research Laboratory, National Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, 610041, Sichuan, China
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