title: Total vitamin C, ascorbic acid, and dehydroascorbic acid concentrations in plasma of critically ill patients.
abstract: Plasma concentrations of the antioxidant vitamin ascorbic acid were measured by high-performance liquid chromatography in critically ill patients in whom the excessive generation of reactive oxygen species could compromise antioxidant defense mechanisms. Median concentrations of both total vitamin C (ascorbic acid and dehydroascorbic acid) and ascorbic acid in these patients were < 25% (P < 0.001) of the values found in healthy control subjects and in subjects in two other disease groups (diabetes, gastritis) in which reactive oxygen species are reported to be increased. The low values could not be explained by age, sex, intake, or treatment differences, but were associated with the severity of the illness and were not prevented by the use of parenteral nutrition containing ascorbic acid. In addition, the vitamin was less stable in blood samples taken from critically ill patients than in similar samples from subjects in the other groups. The findings indicate that antioxidant defenses could be considerably compromised in these very sick patients. If this reduces the patient's capacity to scavenge reactive species, then the potential of these species to damage DNA and lipid membranes could be increased and compromise recovery.
authors.affiliation: Division of Clinical Sciences, University of Leeds, United Kingdom.
authors.forename: C J
authors.initials: CJ
authors.lastname: Schorah
authors.forename: C
authors.initials: C
authors.lastname: Downing
authors.forename: A
authors.initials: A
authors.lastname: Piripitsi
authors.forename: L
authors.initials: L
authors.lastname: Gallivan
authors.forename: A H
authors.initials: AH
authors.lastname: Al-Hazaa
authors.forename: M J
authors.initials: MJ
authors.lastname: Sanderson
authors.forename: A
authors.initials: A
authors.lastname: Bodenham
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood; D001205:Ascorbic Acid / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D016638:Critical Illness; D003683:Dehydroascorbic Acid / Q000097:blood*; D003920:Diabetes Mellitus / Q000097:blood; D005260:Female; D005756:Gastritis / Q000097:blood; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D017382:Reactive Oxygen Species / Q000032:analysis
chemical_list: D017382:Reactive Oxygen Species; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid