title: Mass spectrometric-selected ion monitoring assay for an oxalate absorption test applying [13C2]oxalate.
abstract: In order to assess the significance of the intestinal absorption of oxalate from food for the hyperoxaluria of the individual patient, an oxalate absorption test has been developed using doubly 13C-labelled oxalate and a gas chromatographic selected ion monitoring mass spectrometric assay. This test has been applied to volunteers and patients with urinary stones. The percentage of dose absorbed (range 1-48%) could be determined with a coefficient of variation of 15.2%. The assay to measure doubly 13C-labelled oxalate in the presence of unlabelled oxalate in urine, using the homologue malonic acid as internal standard, is described.
authors.affiliation: Medizinische Klinik und Poliklinik, Allgemeine Innere Medizin, Massenspektrometrie-Labor, Bonn, Germany.
authors.forename: G E
authors.initials: GE
authors.lastname: von Unruh
authors.forename: M A
authors.initials: MA
authors.lastname: Langer
authors.forename: D W
authors.initials: DW
authors.lastname: Paar
authors.forename: A
authors.initials: A
authors.lastname: Hesse
mesh_terms: D002247:Carbon Isotopes; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D007408:Intestinal Absorption; D010070:Oxalates / Q000493:pharmacokinetics* / Q000652:urine; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014545:Urinary Calculi / Q000652:urine
chemical_list: D002247:Carbon Isotopes; D010070:Oxalates