title: Enzymic urea assay: a new colorimetric method based on hydrogen peroxide measurement.
abstract: We describe a new enzymic colorimetric method in which urea is measured in serum by use of a single reagent mixture. Ammonia produced by urea hydrolysis, catalyzed by urease, reacts with glutamate and ATP in the presence of glutamine synthetase. The ADP so produced is assayed in reactions catalyzed sequentially by pyruvate kinase and pyruvate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is measured at 500 or 550 nm in a reaction catalyzed by horseradish peroxidase, with phenol/4-aminophenazone as the chromogen. The reaction is complete in 15 min at 37 degrees C. The standard curve is linear up to a urea concentration of 40 mmol/L. Precision is good; CVs ranged from 2.5% to 3.1%. Results by the present method compared well with those by a candidate Reference Method and are not subject to interferences from commonly used drugs and anticoagulants.
authors.affiliation: Laboratoire d'Analyses Médicales, Montpon-Menestérol, France.
authors.forename: F
authors.initials: F
authors.lastname: Lespinas
authors.forename: G
authors.initials: G
authors.lastname: Dupuy
authors.forename: F
authors.initials: F
authors.lastname: Revol
authors.forename: C
authors.initials: C
authors.lastname: Aubry
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000632:Aminopyrine; D000641:Ammonia / Q000378:metabolism; D003124:Colorimetry; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D006735:Horseradish Peroxidase; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000378:metabolism; D007700:Kinetics; D011770:Pyruvate Kinase / Q000378:metabolism; D013053:Spectrophotometry; D014508:Urea / Q000097:blood*; D014510:Urease / Q000378:metabolism
chemical_list: D005971:Glutamates; D000632:Aminopyrine; D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D000641:Ammonia; D000255:Adenosine Triphosphate; D014508:Urea; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D011770:Pyruvate Kinase; D014510:Urease; D005974:Glutamate-Ammonia Ligase