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Al-Qattan S, Malcolmson C, Mercimek-Andrews S. Lysinuric protein intolerance mimicking N-acetylglutamate synthase deficiency in a nine-year-old boy. Mol Genet Metab Rep 2021; 27:100741. [PMID: 33763330 PMCID: PMC7973239 DOI: 10.1016/j.ymgmr.2021.100741] [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: 01/07/2021] [Revised: 02/28/2021] [Accepted: 03/01/2021] [Indexed: 12/01/2022] Open
Abstract
We report a 9-year-old boy with lysinuric protein intolerance (LPI). He had developmental delay, short stature, failure to thrive, high-protein food aversion, hypothyroidism, growth hormone deficiency, features of hemophagocytic lymphohistiocytosis (HLH), decreased bone mineral density and multiple thoracic spine compression fractures on X-ray. LPI was suspected, but urine amino acid profile and normal orotic acid did not suggest biochemical diagnosis of LPI. Targeted next generation sequencing panel for HLH (including SLC7A7) was organized. Due to elevated glutamine in plasma amino acid analysis, a metabolic consultation was initiated and his asymptomatic post-prandial ammonia was 295 μmol/L. We then suspected n-acetylglutamate synthase or carbamoyl-phosphate synthase I deficiency due to marked hyperammonemia, elevated glutamine level, normal orotic acid, and normalization of ammonia at 2 h of carglumic acid (200 mg/kg/d). His targeted next generation sequencing panel for HLH revealed homozygous pathogenic variant in SLC7A7 ((NM_001126106.2): c.726G>A (p.Trp242*)) and confirmed the diagnosis of LPI. We emphasize the importance of genetic investigations in the diagnosis of LPI. LPI associated hyperammonemia responds to carbaglumic acid. Protein aversion, and failure to thrive should warrant for ammonia measurement. Multisystem disease should include LPI into the differential diagnosis even in the absence of typical biochemical features.
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Affiliation(s)
- Sarah Al-Qattan
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Caroline Malcolmson
- Division of Hematology, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Saadet Mercimek-Andrews
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Medical Genetics, University of Alberta, Stollery Children's Hospital, Edmonton, Alberta, Canada
- Corresponding author at: Department of Medical Genetics, University of Alberta, Stollery Children's Hospital, Alberta Health Services, 8-39 Medical Sciences Building, 8613 – 114 Street, Edmonton, Alberta T6G 2H7, Canada.
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Brannelly NT, Hamilton-Shield JP, Killard AJ. The Measurement of Ammonia in Human Breath and its Potential in Clinical Diagnostics. Crit Rev Anal Chem 2016; 46:490-501. [PMID: 26907707 DOI: 10.1080/10408347.2016.1153949] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ammonia is an important component of metabolism and is involved in many physiological processes. During normal physiology, levels of blood ammonia are between 11 and 50 µM. Elevated blood ammonia levels are associated with a variety of pathological conditions such as liver and kidney dysfunction, Reye's syndrome and a variety of inborn errors of metabolism including urea cycle disorders (UCD), organic acidaemias and hyperinsulinism/hyperammonaemia syndrome in which ammonia may reach levels in excess of 1 mM. It is highly neurotoxic and so effective measurement is critical for assessing and monitoring disease severity and treatment. Ammonia is also a potential biomarker in exercise physiology and studies of drug metabolism. Current ammonia testing is based on blood sampling, which is inconvenient and can be subject to significant analytical errors due to the quality of the sample draw, its handling and preparation for analysis. Blood ammonia is in gaseous equilibrium with the lungs. Recent research has demonstrated the potential use of breath ammonia as a non-invasive means of measuring systemic ammonia. This requires measurement of ammonia in real breath samples with associated temperature, humidity and gas characteristics at concentrations between 50 and several thousand parts per billion. This review explores the diagnostic applications of ammonia measurement and the impact that the move from blood to breath analysis could have on how these processes and diseases are studied and managed.
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Affiliation(s)
- N T Brannelly
- a Department of Biological Biomedical and Analytical Science , University of the West of England , Bristol , UK
| | | | - A J Killard
- a Department of Biological Biomedical and Analytical Science , University of the West of England , Bristol , UK
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Adeva-Andany MM, Carneiro-Freire N, Donapetry-García C, Rañal-Muíño E, López-Pereiro Y. The importance of the ionic product for water to understand the physiology of the acid-base balance in humans. BIOMED RESEARCH INTERNATIONAL 2014; 2014:695281. [PMID: 24877130 PMCID: PMC4022011 DOI: 10.1155/2014/695281] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/31/2014] [Accepted: 04/04/2014] [Indexed: 12/13/2022]
Abstract
Human plasma is an aqueous solution that has to abide by chemical rules such as the principle of electrical neutrality and the constancy of the ionic product for water. These rules define the acid-base balance in the human body. According to the electroneutrality principle, plasma has to be electrically neutral and the sum of its cations equals the sum of its anions. In addition, the ionic product for water has to be constant. Therefore, the plasma concentration of hydrogen ions depends on the plasma ionic composition. Variations in the concentration of plasma ions that alter the relative proportion of anions and cations predictably lead to a change in the plasma concentration of hydrogen ions by driving adaptive adjustments in water ionization that allow plasma electroneutrality while maintaining constant the ionic product for water. The accumulation of plasma anions out of proportion of cations induces an electrical imbalance compensated by a fall of hydroxide ions that brings about a rise in hydrogen ions (acidosis). By contrast, the deficiency of chloride relative to sodium generates plasma alkalosis by increasing hydroxide ions. The adjustment of plasma bicarbonate concentration to these changes is an important compensatory mechanism that protects plasma pH from severe deviations.
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Affiliation(s)
| | | | | | - Eva Rañal-Muíño
- Hospital General Juan Cardona, C/ Pardo Bazán s/n, Ferrol, 15406 La Coruña, Spain
| | - Yosua López-Pereiro
- Hospital General Juan Cardona, C/ Pardo Bazán s/n, Ferrol, 15406 La Coruña, Spain
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Adeva MM, Souto G, Blanco N, Donapetry C. Ammonium metabolism in humans. Metabolism 2012; 61:1495-511. [PMID: 22921946 DOI: 10.1016/j.metabol.2012.07.007] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 06/27/2012] [Accepted: 07/16/2012] [Indexed: 12/13/2022]
Abstract
Free ammonium ions are produced and consumed during cell metabolism. Glutamine synthetase utilizes free ammonium ions to produce glutamine in the cytosol whereas glutaminase and glutamate dehydrogenase generate free ammonium ions in the mitochondria from glutamine and glutamate, respectively. Ammonia and bicarbonate are condensed in the liver mitochondria to yield carbamoylphosphate initiating the urea cycle, the major mechanism of ammonium removal in humans. Healthy kidney produces ammonium which may be released into the systemic circulation or excreted into the urine depending predominantly on acid-base status, so that metabolic acidosis increases urinary ammonium excretion while metabolic alkalosis induces the opposite effect. Brain and skeletal muscle neither remove nor produce ammonium in normal conditions, but they are able to seize ammonium during hyperammonemia, releasing glutamine. Ammonia in gas phase has been detected in exhaled breath and skin, denoting that these organs may participate in nitrogen elimination. Ammonium homeostasis is profoundly altered in liver failure resulting in hyperammonemia due to the deficient ammonium clearance by the diseased liver and to the development of portal collateral circulation that diverts portal blood with high ammonium content to the systemic blood stream. Although blood ammonium concentration is usually elevated in liver disease, a substantial role of ammonium causing hepatic encephalopathy has not been demonstrated in human clinical studies. Hyperammonemia is also produced in urea cycle disorders and other situations leading to either defective ammonium removal or overproduction of ammonium that overcomes liver clearance capacity. Most diseases resulting in hyperammonemia and cerebral edema are preceded by hyperventilation and respiratory alkalosis of unclear origin that may be caused by the intracellular acidosis occurring in these conditions.
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Abstract
Ammonia is produced continuously in the body. It crosses the blood-brain barrier readily and at increased concentration it is toxic to the brain. A highly integrated system protects against this: ammonia produced during metabolism is detoxified temporarily by incorporation into the non-toxic amino acid glutamine. This is transported safely in the circulation to the small intestine, where ammonia is released, carried directly to the liver in the portal blood, converted to non-toxic urea and finally excreted in urine. As a result, plasma concentrations of ammonia in the systemic circulation are normally very low (<40 μmol/L). Hyperammonaemia develops if the urea cycle cannot control the ammonia load. This occurs when the load is excessive, portal blood from the intestines bypasses the liver and/or the urea cycle functions poorly. By far, the commonest cause is liver damage. This review focuses on other causes in adults. Because they are much less common, the diagnosis may be missed or delayed, with disastrous consequences. There is effective treatment for most of them, but it must be instituted promptly to avoid fatality or long-term neurological damage. Of particular concern are unsuspected inherited defects of the urea cycle and fatty acid oxidation presenting with catastrophic illness in previously normal individuals. Early identification of the problem is the challenge.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, C Level MP 8, South Block, Southampton Hospital, Tremona Road, Southampton SO16 6YD, UK.
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Abstract
Patients experiencing acute elevations of ammonia present to the ICU with encephalopathy, which may progress quickly to cerebral herniation. Patient survival requires immediate treatment of intracerebral hypertension and the reduction of ammonia levels. When hyperammonemia is not thought to be the result of liver failure, treatment for an occult disorder of metabolism must begin prior to the confirmation of an etiology. This article reviews ammonia metabolism, the effects of ammonia on the brain, the causes of hyperammonemia, and the diagnosis of inborn errors of metabolism in adult patients.
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Affiliation(s)
- Alison S Clay
- Department of Surgery and Medicine, Duke University Medical Center, Box 2945, Durham, NC 27710, USA.
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Tan IK, Gajra B. Plasma and Urine Amino Acid Profiles in a Healthy Adult Population of Singapore. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2006. [DOI: 10.47102/annals-acadmedsg.v35n7p468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Introduction: The analysis of amino acids in plasma and urine was introduced in Singapore when a laboratory for the investigation of inherited metabolic disorders was established by the Ministry of Health. Reference ranges are required for interpreting test results and making diagnoses. Initially, reference ranges established for Caucasians were used as there were no local data and we were unable to find data obtained by the same analytical method for Asian populations. This was not considered an ideal and long-term solution, as Singaporeans may have amino acid concentrations quite different from those of Caucasians due to genetic factors, dietary difference, environment, and other influences. This study was therefore undertaken when a number of healthy laboratory personnel volunteered to provide specimens for the study.
Materials and Methods: Sixty healthy male and female laboratory workers not on any form of medication were recruited. They consisted of 24 males (range, 23 to 58 years) and 36 females (range, 20 to 60 years), with a mean age of 38.7 years. Non-fasting random blood and urine specimens were collected on ice. Removal of protein and peptides from heparinised plasma and urine was achieved by ultrafiltration through protein-exclusion membrane. Amino acid analysis on the ultrafiltrate was performed by a dedicated Beckman 6300 Amino Acid Analyzer using a cation exchange resin column and post-column colour reaction with ninhydrin reagent. Urine creatinine was measured by a Beckman LX 20 PRO Analyzer. Results for urine amino acids were expressed as µmol/mmol of creatinine.
Results: Reference ranges for 32 amino acids in blood plasma and 36 amino acids in urine were calculated by a non-parametric method using the SPSS statistical calculation software. The ranges cover 95% of the population and the low and high limits of each reference range represent the 2.5th percentile and 97.5th percentile of the frequency distribution respectively.
Conclusions: We observed differences in the reference ranges of several plasma and urine amino acids between Singaporean and Caucasian populations. Moreover, the list of urine amino acids for Caucasian population is incomplete. We have therefore discontinued the use of reference values established for Caucasians and adopted the results of this study for our patient diagnostic work.
Key words: Blood amino acid, Normal ranges, Reference values, Urine amino acids
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Abstract
CONTEXT Inborn errors of metabolism cause hereditary metabolic diseases (HMD) and classically they result from the lack of activity of one or more specific enzymes or defects in the transportation of proteins. OBJECTIVES A clinical review of inborn errors of metabolism (IEM) to give a practical approach to the physician with figures and tables to help in understanding the more common groups of these disorders. DATA SOURCE A systematic review of the clinical and biochemical basis of IEM in the literature, especially considering the last ten years and a classic textbook (Scriver CR et al, 1995). SELECTION OF STUDIES A selection of 108 references about IEM by experts in the subject was made. Clinical cases are presented with the peculiar symptoms of various diseases. DATA SYNTHESIS IEM are frequently misdiagnosed because the general practitioner, or pediatrician in the neonatal or intensive care units, does not think about this diagnosis until the more common cause have been ruled out. This review includes inheritance patterns and clinical and laboratory findings of the more common IEM diseases within a clinical classification that give a general idea about these disorders. A summary of treatment types for metabolic inherited diseases is given. CONCLUSIONS IEM are not rare diseases, unlike previous thinking about them, and IEM patients form part of the clientele in emergency rooms at general hospitals and in intensive care units. They are also to be found in neurological, pediatric, obstetrics, surgical and psychiatric clinics seeking diagnoses, prognoses and therapeutic or supportive treatment.
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Affiliation(s)
- A M Martins
- Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, Brazil.
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Gare M, Shalit M, Gutman A. Lysinuric protein intolerance presenting as coma in a middle-aged man. West J Med 1996; 165:231-3. [PMID: 8987436 PMCID: PMC1303758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M Gare
- Department of Internal Medicine, Michael Reese Hospital, Chicago, Illinois 60616, USA
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Chow WC, Ng HS, Tan IK, Thum TY. Case report: recurrent hyperammonaemic encephalopathy due to citrullinaemia in a 52 year old man. J Gastroenterol Hepatol 1996; 11:621-5. [PMID: 8840235 DOI: 10.1111/j.1440-1746.1996.tb00303.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The present report describes a Chinese male who presented for the first time with recurrent encephalopathy and hyperammonaemia at the age of 52 years. He was found to have citrullinaemia. To our knowledge, this is the first Chinese with citrullinaemia and the first non-Japanese who has the variant form of presentation. The patient also has the longest asymptomatic period for citrullinaemia so far described. The patient's biochemical derangement, clinical features and the postulation of his late presentation are discussed. It is noteworthy that simple therapeutic measures, such as lactulose and dietary protein restriction, controlled his symptoms well.
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Affiliation(s)
- W C Chow
- Department of Gastroenterology, Singapore General Hospital, Singapore
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Hughes PJ, Kiely PD, Davies PT, Dick JP, Turner AM, Lane RJ. Hyperammonaemia--an important cause of encephalopathy: three case reports. Ann Clin Biochem 1993; 30 ( Pt 2):225-7. [PMID: 8466166 DOI: 10.1177/000456329303000229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- P J Hughes
- Wessex Neurological Centre, Southampton General Hospital, UK
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Tinuper P, Montagna P, Cortelli P, Avoni P, Lugaresi A, Schoch P, Bonetti EP, Gallassi R, Sforza E, Lugaresi E. Idiopathic recurring stupor: a case with possible involvement of the gamma-aminobutyric acid (GABA)ergic system. Ann Neurol 1992; 31:503-6. [PMID: 1317696 DOI: 10.1002/ana.410310507] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A patient had recurrent spontaneous episodes of stupor or coma in the absence of toxic, metabolic, or structural brain damage. Ictal electroencephalography showed fast 14 Hz background activity; sleep studies excluded narcolepsy. Flumazenil (Anexate), a benzodiazepine antagonist, promptly resolved the episodes and normalized the electroencephalogram. Radioreceptor binding studies showed the presence of a ligand to the central benzodiazepine receptor in plasma and cerebrospinal fluid during the episodes, suggesting a gamma-aminobutyric acid (GABA)ergic system involvement in the origin of the attacks.
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Affiliation(s)
- P Tinuper
- Institute of Neurology, University of Bologna, Italy
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