title: Cerebral glutamine concentration and lactate-pyruvate ratio in patients with acute liver failure.
abstract: OBJECTIVE
  Hyperammonemia causes brain edema and high intracranial pressure (ICP) in acute liver failure (ALF) by accumulation of glutamine in brain. Since a high-level glutamine may compromise mitochondrial function, the aim of this study was to determine if the lactate-pyruvate ratio is associated with a rise in the glutamine concentration and ICP.
  
  
  METHODS
  In 13 patients with ALF (8F/5M; median age 46 (range 18-66) years) the cerebral extracellular concentrations of glutamine, lactate, and pyruvate were measured by in vivo brain microdialysis together with ICP and cerebral perfusion pressure (CPP).
  
  
  RESULTS
  The cerebral glutamine concentration was 4,396 (1,011-9,712) microM, lactate 2.15 (1.1-4.45) mM, and pyruvate 101 (43-255) microM. The lactate-pyruvate ratio was 21 (16-40), ICP 20 (2-28) mmHg, and CPP 72 (56-115) mmHg. Cerebral glutamine concentration correlated with the lactate-pyruvate ratio (r = 0.89, P < 0.05). Also the ICP, but not CPP, correlated to the lactate-pyruvate ratio (r = 0.64, P < 0.05).
  
  
  CONCLUSIONS
  ICP and the cerebral glutamine concentration in patients with ALF correlate to the lactate-pyruvate ratio. Since CPP was sufficient in all patients the rise in lactate-pyruvate ratio indicates that accumulation of glutamine compromises mitochondrial function and causes intracranial hypertension.
authors.affiliation: Department of Hepatology, section A-2121, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 9, 2100, Copenhagen O, Denmark.
authors.forename: Peter Nissen
authors.initials: PN
authors.lastname: Bjerring
authors.forename: John
authors.initials: J
authors.lastname: Hauerberg
authors.forename: Hans-Jorgen
authors.initials: HJ
authors.lastname: Frederiksen
authors.forename: Linda
authors.initials: L
authors.lastname: Jorgensen
authors.forename: Bent Adel
authors.initials: BA
authors.lastname: Hansen
authors.forename: Flemming
authors.initials: F
authors.lastname: Tofteng
authors.forename: Fin Stolze
authors.initials: FS
authors.lastname: Larsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001253:Astrocytes / Q000473:pathology; D001921:Brain / Q000378:metabolism; D001929:Brain Edema / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D003422:Critical Care; D005260:Female; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D022124:Hyperammonemia / Q000209:etiology / Q000378:metabolism; D019586:Intracranial Hypertension / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D019344:Lactic Acid / Q000378:metabolism*; D017114:Liver Failure, Acute / Q000150:complications / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism*; D012720:Severity of Illness Index
chemical_list: D005973:Glutamine; D019344:Lactic Acid; D019289:Pyruvic Acid