title: Relation between pyridoxal and pyridoxal phosphate concentrations in plasma, red cells, and white cells in patients with critical illness.
abstract: BACKGROUND
  Evidence suggests that the relation between plasma and red cell vitamin B-6 concentrations is perturbed as part of the systemic inflammatory response in critically ill patients.
  
  
  OBJECTIVE
  The aim was to examine the cross-sectional and longitudinal interrelations between pyridoxal (PL) and pyridoxal phosphate (PLP) concentrations in plasma and red and white cells in patients with critical illness.
  
  
  METHODS
  PLP and PL concentrations were measured by HPLC in plasma and red and white cells in normal subjects (n = 126) and critically ill patients (n = 96) on admission and on follow-up.
  
  
  RESULTS
  On admission, compared with the controls, median plasma PLP and PL (P < 0.001 and < 0.01, respectively) and red cell PLP and PL (P < 0.001 and < 0.05, respectively) and their ratio (PLP:PL) in plasma and red cells (P < 0.001 and < 0.01, respectively) were significantly lower in the critically ill. In critically ill patients, plasma PLP:PL was significantly lower than red cell PLP:PL (P = 0.001) and white cell PLP:PL (P = 0.008). Plasma PL concentration was directly associated with both red cell PL (r(s) = 0.73, P < 0.001) and white cell PL (r(s) = 0.68, P < 0.001). Red cell PL and white cell PL were directly associated with red cell PLP (r(s) = 0.82, P < 0.001) and white cell PLP (r(s) = 0.68, P < 0.001), respectively. Longitudinal measurements (n = 48) were similar.
  
  
  CONCLUSIONS
  The relation between plasma PLP and PL was significantly perturbed in critical illness. This effect was less pronounced in red and white cells. Therefore, these results confirm the hypothesis that intracellular PLP concentrations are more likely to be a reliable measure of status than are plasma measurements in the critically ill patient.
authors.affiliation: University Department of Surgery, Royal Infirmary, Glasgow, United Kingdom.
authors.forename: Aikaterini T
authors.initials: AT
authors.lastname: Vasilaki
authors.forename: Donald C
authors.initials: DC
authors.lastname: McMillan
authors.forename: John
authors.initials: J
authors.lastname: Kinsella
authors.forename: Andrew
authors.initials: A
authors.lastname: Duncan
authors.forename: Denis St J
authors.initials: DS
authors.lastname: O'Reilly
authors.forename: Dinesh
authors.initials: D
authors.lastname: Talwar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D016638:Critical Illness; D003430:Cross-Sectional Studies; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000097:blood; D007962:Leukocytes / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D011730:Pyridoxal / Q000097:blood*; D011732:Pyridoxal Phosphate / Q000097:blood*
chemical_list: D015415:Biomarkers; D011730:Pyridoxal; D011732:Pyridoxal Phosphate