title: Retinol potentiates the inhibitory effect of ascorbic acid on uric acid assay.
abstract: BACKGROUND
  The interference of ascorbic acid in the determination of plasma uric acid concentrations, by decreasing the formation of chromophore in Trinder's reaction, is well known. By contrast, the effects of other antioxidant vitamins, such as retinol and alpha-tocopherol have not been investigated. Knowledge of the analytical interaction of these antioxidants in the uric acid assay would be useful.
  
  
  METHODS
  The effect of a mix of vitamins (Cernevit) on uric acid analysis in a patient hospitalized in a neurological intensive care unit was observed. The effects of the different antioxidant components of the mixture (retinol, alpha-tocopherol and ascorbic acid) on the concentration of uric acid from a pool of plasma were also tested.
  
  
  RESULTS
  Among the different combinations of vitamins tested, only retinol potentiated the antioxidant effect of ascorbic acid. The most marked effect was observed with 80 IU/mL of retinol and 5.7 mmol/L of ascorbic acid.
  
  
  CONCLUSIONS
  We demonstrate for the first time the synergistic interference of ascorbic acid and retinol on the measurement of uric acid in plasma. We established that ascorbic acid interference is potentiated by regeneration of reduced ascorbic acid by retinol. Such interference must be kept in mind to avoid misinterpreting low plasma uric acid concentrations in patients in whom this analyte is critical.
authors.affiliation: Department of Biochemistry, Clermont-Ferrand Teaching Hospital, Clermont-Ferrand, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Bouvier
authors.forename: Vincent
authors.initials: V
authors.lastname: Sapin
authors.forename: Michèle
authors.initials: M
authors.lastname: Bonnard-Gougeon
authors.forename: Geoffroy
authors.initials: G
authors.lastname: Marceau
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D004357:Drug Synergism; D006801:Humans; D007362:Intensive Care Units; D014527:Uric Acid / Q000097:blood*; D014801:Vitamin A / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D014815:Vitamins; D014801:Vitamin A; D014527:Uric Acid; D024502:alpha-Tocopherol; D001205:Ascorbic Acid