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Yang Y, Mu X, Wu Z, An Z, Li S. Renal hypouricemia complicated with kidney stone: a case report. Front Med (Lausanne) 2024; 11:1218232. [PMID: 38384421 PMCID: PMC10878990 DOI: 10.3389/fmed.2024.1218232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 01/22/2024] [Indexed: 02/23/2024] Open
Abstract
Renal hypouricemia (RHUC) is a rare autosomal recessive disorder characterized by impaired renal tubular uric acid reabsorption and abnormally high uric acid clearance, which may be manifested by reduced serum uric acid (SUA) levels and elevated fractional excretion of uric acid (FE-UA >10%). Most RHUC patients are often asymptomatic or have accidentally decreased SUA levels during health examinations, while others develop kidney stones and exercise-induced acute kidney injury (EIAKI). We now report a case of RHUC complicated with an asymptomatic kidney stone, and we identified a heterozygous mutation of c.269G > A (p.R90H) and a novel heterozygous mutation of c.674C > G (p.T225R) in the SLC22A12 gene in the patient through whole exon gene detection (NGS method). This case offers valuable insights into the mechanisms, clinical management, and prognosis of RHUC and its associated complications.
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Affiliation(s)
- Yuhao Yang
- General Practice Ward/International Medical Center Ward, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xingyu Mu
- General Practice Ward/International Medical Center Ward, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zengxiang Wu
- General Practice Ward/International Medical Center Ward, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhenmei An
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Shuangqing Li
- General Practice Ward/International Medical Center Ward, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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Terkeltaub R. Emerging Urate-Lowering Drugs and Pharmacologic Treatment Strategies for Gout: A Narrative Review. Drugs 2023; 83:1501-1521. [PMID: 37819612 DOI: 10.1007/s40265-023-01944-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2023] [Indexed: 10/13/2023]
Abstract
Hyperuricemia with consequent monosodium urate crystal deposition leads to gout, characterized by painful, incapacitating inflammatory arthritis flares that are also associated with increased cardiovascular event and related mortality risk. This narrative review focuses on emerging pharmacologic urate-lowering treatment (ULT) and management strategies in gout. Undertreated, gout can progress to palpable tophi and joint damage. In oral ULT clinical trials, target serum urate of < 6.0 mg/dL can be achieved in ~ 80-90% of subjects, with flare burden reduction by 1-2 years. However, real-world ULT results are far less successful, due to both singular patient nonadherence and prescriber undertreatment, particularly in primary care, where most patients are managed. Multiple dose titrations commonly needed to optimize first-line allopurinol ULT monotherapy, and substantial potential toxicities and other limitations of approved, marketed oral monotherapy ULT drugs, promote hyperuricemia undertreatment. Common gout comorbidities with associated increased mortality (e.g., moderate-severe chronic kidney disease [CKD], type 2 diabetes, hypertension, atherosclerosis, heart failure) heighten ULT treatment complexity and emphasize unmet needs for better and more rapid clinically significant outcomes, including attenuated gout flare burden. The gout drug armamentarium will be expanded by integrating sodium-glucose cotransporter-2 (SGLT2) inhibitors with uricosuric and anti-inflammatory properties as well as clinically indicated antidiabetic, nephroprotective, and/or cardioprotective effects. The broad ULT developmental pipeline is loaded with multiple uricosurics that selectively target uric acid transporter 1 (URAT1). Evolving ULT approaches include administering selected gut anaerobic purine degrading bacteria (PDB), modulating intestinal urate transport, and employing liver-targeted xanthine oxidoreductase mRNA knockdown. Last, emerging measures to decrease the immunogenicity of systemically administered recombinant uricases should simplify treatment regimens and further improve outcomes in managing the most severe gout phenotypes.
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Affiliation(s)
- Robert Terkeltaub
- Division of Rheumatology, Allergy and Immunology, Department of Medicine, University of California, 9500 Gilman Drive, San Diego, La Jolla, CA, 92093, USA.
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Aizawa C, Okabe M, Takahashi D, Sagasaki M, Watanabe M, Fujimoto T, Yoshioka Y, Katsuma A, Kimura A, Miyamoto D, Sato N, Okamoto K, Ichida K, Miyazaki Y, Yokoo T. Possible Use of Non-purine Selective Xanthine Oxidoreductase Inhibitors for Prevention of Exercise-induced Acute Kidney Injury Associated with Renal Hypouricemia. Intern Med 2023; 62:2725-2730. [PMID: 36754409 PMCID: PMC10569912 DOI: 10.2169/internalmedicine.0678-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 01/04/2023] [Indexed: 02/10/2023] Open
Abstract
Exercise-induced acute kidney injury (EIAKI) is frequently complicated with renal hypouricemia (RHUC). In patients with RHUC, limiting anaerobic exercise can prevent EIAKI. However, it is challenging to reduce exercise intensity in athletes. We herein report a 16-year-old Japanese football player with familial RHUC with compound heterozygous mutations in urate transporter 1 (URAT1) who presented with recurrent EIAKI. As prophylaxis (hydration during exercise) could not prevent EIAKI, febuxostat was initiated. EIAKI was not observed for 16 months despite exercising intensively. Hence, non-purine-selective xanthine oxidoreductase inhibitors may decrease the incidence of EIAKI in athletes with RHUC.
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Affiliation(s)
- Chiharu Aizawa
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
| | - Masahiro Okabe
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | | | - Makoto Sagasaki
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Department of Nephrology and Hypertension, Atsugi City Hospital, Japan
| | - Mao Watanabe
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Toshinari Fujimoto
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Yuuki Yoshioka
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Ai Katsuma
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Ai Kimura
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Daisuke Miyamoto
- Department of Endocrinology, Metabolism and Nephrology, Graduate School of Medicine, Nippon Medical School, Japan
| | - Nana Sato
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Ken Okamoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Kimiyoshi Ichida
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Department of Pathophysiology, Faculty of Pharmaceutical Sciences, Tokyo University of Pharmacy and Life Sciences, Japan
| | - Yoichi Miyazaki
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Japan
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University Daisan Hospital, Japan
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Tian Q, He C, Wang Z, Hun M, Fu YC, Zhao M, He Q. Relationship between serum uric acid and estimated glomerular filtration rate in adolescents aged 12-19 years with different body mass indices: a cross-sectional study. Front Endocrinol (Lausanne) 2023; 14:1138513. [PMID: 37564990 PMCID: PMC10410468 DOI: 10.3389/fendo.2023.1138513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/28/2023] [Indexed: 08/12/2023] Open
Abstract
Background Globally, chronic kidney disease (CKD) is a growing public health concern. Serum uric acid (SUA) is an easily detectable and readily available biochemical indicator that has long been recognized as an independent risk factor for CKD. In addition, studies have indicated a potential relationship between SUA and body mass index (BMI). However, studies on the effect of SUA levels on the estimated glomerular filtration rate (eGFR) in adolescents with different BMIs are very rare. Methods Weighted multiple regression analysis was used to estimate the independent relationship between SUA and log-transformed eGFR. Additionally, we used a weighted generalized additive model and smooth curve fitting to describe the nonlinear relationships in the subgroup analysis. Results First, SUA was negatively associated with log-transformed eGFR even after adjusting for all covariates (β=-0.0177, 95% CI: -0.0203-0.0151, P<0.0001). Second, the results of the stratified analysis found that after adjusting for all covariates, the decrease in log-transformed eGFR due to changes in per SUA levels (Per 1, mg/dL increase) was elevated in female adolescents (β=-0.0177, 95% CI: -0.0216, -0.0138, P<0.0001), adolescents aged 12-15 years (β=-0.0163, 95% CI: -0.0200, -0.0125, P<0.0001) and black (β=-0.0199, 95% CI: -0.0251, -0.0148, P<0.0001) adolescents. Furthermore, we found that adolescents with a higher BMI had higher SUA levels, and the effect of SUA on eGFR was significantly higher in underweight adolescents (β=-0.0386, 95% CI: (-0.0550, -0.0223), P<0.0001). Conclusion SUA was negatively associated with the eGFR in adolescents aged 12-19 years. Furthermore, we found for the first time that SUA affects the eGFR differently in adolescents with different BMIs. This effect was particularly significant in underweight adolescents.
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Affiliation(s)
- Qiuwei Tian
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Caixia He
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Zisai Wang
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Marady Hun
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yi-Cheng Fu
- Department of Pediatrics, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Mingyi Zhao
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Qingnan He
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
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Lee H, Kang D, Lee H, Yim J, Kim M, Park CW. Renal hypouricemia as the cause of exercise-induced acute kidney injury. Kidney Res Clin Pract 2023; 42:534-537. [PMID: 37448289 PMCID: PMC10407641 DOI: 10.23876/j.krcp.23.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 02/20/2023] [Indexed: 07/15/2023] Open
Affiliation(s)
- Haeun Lee
- Division of Nephrology, Department of Internal Medicine, Presbyterian Medical Center, Jeonju, Republic of Korea
| | - Donghyuk Kang
- Department of Nephrology and Hypertension, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Hanbi Lee
- Division of Nephrology, Department of Internal Medicine, The Catholic University of Korea, Seoul St. Mary’s Hospital, Seoul, Republic of Korea
| | - Jisook Yim
- Department of Laboratory Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Myungshin Kim
- Department of Laboratory Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Cheol Whee Park
- Division of Nephrology, Department of Internal Medicine, The Catholic University of Korea, Seoul St. Mary’s Hospital, Seoul, Republic of Korea
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Zhao X, Yang T, Zhou J, Chen Y, Shen Q, Zhang J, Qiu Q. Fucoidan alleviates the hepatorenal syndrome through inhibition organic solute transporter α/β to reduce bile acids reabsorption. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2023; 5:100159. [PMID: 37416532 PMCID: PMC10320405 DOI: 10.1016/j.crphar.2023.100159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 03/03/2023] [Accepted: 06/22/2023] [Indexed: 07/08/2023] Open
Abstract
The high levels of bile acids are a critical factor in hepatorenal syndrome. Organic solute transporter α/β (Ostα/β) participate in bile acids reabsorption in the kidney. Fucoidan has the great potential in protecting against liver and kidney injury. However, whether Ostα/β increase bile acids reabsorption in bile duct ligature (BDL)-induced hepatorenal syndrome and the blockade of fucoidan are still not clear. Male mice that received BDL were given to fucoidan (at 12.5, 25 and 50 mg/kg) through intraperitoneal injection once daily for three weeks. The serum, liver and kidney samples of these experimental mice were collected to carry out biochemical, pathological and Western blot analysis. In this study, fucoidan significantly lowered serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), decreased serum levels of uric acid, creatinine and uric nitrogen, restored the deregulation of the renal urate transporter 1 (URAT1), organic anion transporter 1 (OAT1), and organic cation/carnitine transporter 1/2 (OCTN1/2), consistence with alleviation BDL-induced liver and kidney dysfunction, inflammation and fibrosis in mice. Furthermore, fucoidan significantly hampered Ostα/β and reduced bile acids reabsorption in BDL-induced mice, protected against AML12 and HK-2 cells injury in vitro. These results demonstrate that fucoidan alleviates BDL-induced hepatorenal syndrome through inhibition Ostα/β to reduce bile acids reabsorption in mice. Therefore, suppression of Ostα/β by fucoidan may be a novel strategy for attenuating hepatorenal syndrome.
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Mazzierli T, Cirillo L, Palazzo V, Ravaglia F, Becherucci F. Clinical features suggesting renal hypouricemia as the cause of acute kidney injury: a case report and review of the literature. J Nephrol 2023; 36:651-657. [PMID: 36418779 PMCID: PMC10089983 DOI: 10.1007/s40620-022-01494-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/10/2022] [Indexed: 11/25/2022]
Abstract
Hypouricemia is defined as a level of serum uric acid below 2 mg/dl. Renal hypouricemia is related to genetic defects of the uric acid tubular transporters urate transporter 1 and glucose transporter 9. Patients with renal hypouricemia can be completely asymptomatic or can develop uric acid kidney stones or acute kidney injury, particularly after exercise. Renal hypouricemia is especially challenging to diagnose in patients with acute kidney injury, due to the nonspecific clinical, hematochemical and histological features. No common features are reported in the literature that could help clinicians identify renal hypouricemia-acute kidney injury. Currently available guidelines on diagnosis and management of renal hypouricemia provide limited support in defining clues for the differential diagnosis of renal hypouricemia, which is usually suspected when hypouricemia is found in asymptomatic patients. In this paper we report a case of renal hypouricemia-acute kidney injury developing after exercise. We carried out a review of the literature spanning from the first clinical description of renal hypouricemia in 1974 until 2022. We selected a series of clinical features suggesting a diagnosis of renal hypouricemia-acute kidney injury. This may help clinicians to suspect renal hypouricemia in patients with acute kidney injury and to avoid invasive, costly and inconclusive exams such as renal biopsy. Considering the excellent outcome of the patients reported in the literature, we suggest a "wait-and-see" approach with supportive therapy and confirmation of the disease via genetic testing.
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Affiliation(s)
- Tommaso Mazzierli
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Luigi Cirillo
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy
- Nephrology and Dialysis Unit, Meyer Children's Hospital IRCCS, Florence, Italy
| | - Viviana Palazzo
- Medical Genetics Unit, Meyer Children's Hospital IRCCS, Florence, Italy
| | | | - Francesca Becherucci
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy.
- Nephrology and Dialysis Unit, Meyer Children's Hospital IRCCS, Florence, Italy.
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Toyoda Y, Cho SK, Tasic V, Pavelcová K, Bohatá J, Suzuki H, David VA, Yoon J, Pallaiova A, Šaligová J, Nousome D, Cachau R, Winkler CA, Takada T, Stibůrková B. Identification of a dysfunctional exon-skipping splice variant in GLUT9/ SLC2A9 causal for renal hypouricemia type 2. Front Genet 2023; 13:1048330. [PMID: 36733941 PMCID: PMC9887137 DOI: 10.3389/fgene.2022.1048330] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/21/2022] [Indexed: 01/18/2023] Open
Abstract
Renal hypouricemia (RHUC) is a pathological condition characterized by extremely low serum urate and overexcretion of urate in the kidney; this inheritable disorder is classified into type 1 and type 2 based on causative genes encoding physiologically-important urate transporters, URAT1 and GLUT9, respectively; however, research on RHUC type 2 is still behind type 1. We herein describe a typical familial case of RHUC type 2 found in a Slovak family with severe hypouricemia and hyperuricosuria. Via clinico-genetic analyses including whole exome sequencing and in vitro functional assays, we identified an intronic GLUT9 variant, c.1419+1G>A, as the causal mutation that could lead the expression of p.Gly431GlufsTer28, a functionally-null variant resulting from exon 11 skipping. The causal relationship was also confirmed in another unrelated Macedonian family with mild hypouricemia. Accordingly, non-coding regions should be also kept in mind during genetic diagnosis for hypouricemia. Our findings provide a better pathogenic understanding of RHUC and pathophysiological importance of GLUT9.
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Affiliation(s)
- Yu Toyoda
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo, Japan
| | - Sung Kweon Cho
- Molecular Genetics Epidemiology Section, Basic Research Laboratory, National Cancer Institute and Frederick National Laboratory for Cancer Research, Frederick, MD, United States,Department of Pharmacology, Ajou University School of Medicine, Suwon, South Korea
| | - Velibor Tasic
- Faculty of Medicine, University Ss. Cyril and Methodius, Skopje, North Macedonia
| | | | | | - Hiroshi Suzuki
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo, Japan
| | - Victor A. David
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo, Japan
| | - Jaeho Yoon
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States
| | | | - Jana Šaligová
- Metabolic Clinic, Children’s Faculty Hospital, Košice, Slovakia
| | - Darryl Nousome
- CCR Collaborative Bioinformatics Resource, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States
| | - Raul Cachau
- Integrated Data Science Section, Research Technologies Branch, National Institute of Allergies and Infectious Diseases, Bethesda, MD, United States
| | - Cheryl A. Winkler
- Molecular Genetics Epidemiology Section, Basic Research Laboratory, National Cancer Institute and Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | - Tappei Takada
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo, Japan
| | - Blanka Stibůrková
- Institute of Rheumatology, Prague, Czechia,Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czechia,Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czechia,*Correspondence: Blanka Stibůrková,
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Kim GH, Jun JB. Altered Serum Uric Acid Levels in Kidney Disorders. LIFE (BASEL, SWITZERLAND) 2022; 12:life12111891. [PMID: 36431026 PMCID: PMC9692609 DOI: 10.3390/life12111891] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/07/2022] [Accepted: 11/13/2022] [Indexed: 11/17/2022]
Abstract
Serum uric acid levels are altered by kidney disorders because the kidneys play a dominant role in uric acid excretion. Here, major kidney disorders which accompany hyperuricemia or hypouricemia, including their pathophysiology, are discussed. Chronic kidney disease (CKD) and hyperuricemia are frequently associated, but recent clinical trials have not supported the pathogenic roles of hyperuricemia in CKD incidence and progression. Diabetes mellitus (DM) is often associated with hyperuricemia, and hyperuricemia may be associated with an increased risk of diabetic kidney disease in patients with type 2 DM. Sodium-glucose cotransporter 2 inhibitors have a uricosuric effect and can relieve hyperuricemia in DM. Autosomal dominant tubulointerstitial kidney disease (ADTKD) is an important hereditary kidney disease, mainly caused by mutations of uromodulin (UMOD) or mucin-1 (MUC-1). Hyperuricemia and gout are the major clinical manifestations of ADTKD-UMOD and ADTKD-MUC1. Renal hypouricemia is caused by URAT1 or GLUT9 loss-of-function mutations and renders patients susceptible to exercise-induced acute kidney injury, probably because of excessive urinary uric acid excretion. Hypouricemia derived from renal uric acid wasting is a component of Fanconi syndrome, which can be hereditary or acquired. During treatment for human immunodeficiency virus, hepatitis B or cytomegalovirus, tenofovir, adefovir, and cidofovir may cause drug-induced renal Fanconi syndrome. In coronavirus disease 2019, hypouricemia due to proximal tubular injury is related to disease severity, including respiratory failure. Finally, serum uric acid and the fractional excretion of uric acid are indicative of plasma volume status; hyperuricemia caused by the enhanced uric acid reabsorption can be induced by volume depletion, and hypouricemia caused by an increased fractional excretion of uric acid is the characteristic finding in syndromes of inappropriate anti-diuresis, cerebral/renal salt wasting, and thiazide-induced hyponatremia. Molecular mechanisms by which uric acid transport is dysregulated in volume or water balance disorders need to be investigated.
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Affiliation(s)
- Gheun-Ho Kim
- Department of Internal Medicine, Hanyang University College of Medicine, Seoul 04763, Republic of Korea
- Correspondence: ; Tel.: +82-2-2290-8318
| | - Jae-Bum Jun
- Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, Seoul 04763, Republic of Korea
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Genetic Basis of the Epidemiological Features and Clinical Significance of Renal Hypouricemia. Biomedicines 2022; 10:biomedicines10071696. [PMID: 35885001 PMCID: PMC9313227 DOI: 10.3390/biomedicines10071696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 11/17/2022] Open
Abstract
A genetic defect in urate transporter 1 (URAT1) is the major cause of renal hypouricemia (RHUC). Although RHUC is detected using a serum uric acid (UA) concentration <2.0 mg/dL, the relationship between the genetic state of URAT1 and serum UA concentration is not clear. Homozygosity and compound heterozygosity with respect to mutant URAT1 alleles are associated with a serum UA concentration of <1.0 mg/dL and are present at a prevalence of ~0.1% in Japan. In heterozygous individuals, the prevalence of a serum UA of 1.1−2.0 mg/dL is much higher in women than in men. The frequency of mutant URAT1 alleles is as high as 3% in the general Japanese population. The expansion of a specific mutant URAT1 allele derived from a single mutant gene that occurred in ancient times is reflected in modern Japan at a high frequency. Similar findings were reported in Roma populations in Europe. These phenomena are thought to reflect the ancient migration history of each ethnic group (founder effects). Exercise-induced acute kidney injury (EI-AKI) is mostly observed in individuals with homozygous/compound heterozygous URAT1 mutation, and laboratory experiments suggested that a high UA load on the renal tubules is a plausible mechanism for EI-AKI.
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