title: Liquid citrate acidification introduces significant glucose bias and leads to misclassification of patients with diabetes.
abstract: BACKGROUND
  Glucose measurements are crucial in diabetes diagnosis. We aimed to assess the effectiveness of liquid citrate acidification in preventing glycolysis and investigate glucose stability in serum, sodium fluoride (NaF/KOx) and Glucomedics tubes.
  
  
  METHODS
  Samples from 40 participants were collected in serum, lithium-heparin (LiH), sodium fluoride/potassium oxalate (NaF/KOx) and Glucomedics tubes. Glucose was measured within 60 min (baseline), 120 and 180 min from venipuncture. Serum, NaF/KOx and Glucomedics values at baseline were compared to LiH glucose concentration. Additionally, glucose values measured at 120 and 180 min from each tube were compared with the baseline value. Mean absolute bias for each tube and time point was calculated and compared to recommended criteria. The regression equation obtained comparing citrate to NaF/KOx tubes was used to recalculate glucose results retrieved from the laboratory information system.
  
  
  RESULTS
  Glucose measured in Glucomedics was higher (9.9%; p<0.001), while glucose in NaF/KOx and serum was lower compared to LiH (2.4%; p<0.001 and 3.2%; p<0.001, respectively). Biases for all tubes were clinically significant. Glucose remained unchanged at room temperature in all tubes for up to 180 min after venipuncture. Observed bias caused by Glucomedics leads to a 10.6% increase in diabetes prevalence (p<0.001).
  
  
  CONCLUSIONS
  Inhibition of glycolysis is most effectively achieved using liquid citrate acidification, compared to LiH, NaF/KOx or serum. Due to clinically significant bias relative to reference glucose, the interchangeable use of different tube types for serial glucose measurements is not recommended. The replacement of NaF/KOx with Glucomedics tubes substantially impacts glucose results, giving marked rise in diabetes prevalence.
authors.forename: Gordana
authors.initials: G
authors.lastname: Juricic
authors.forename: Lara Milevoj
authors.initials: LM
authors.lastname: Kopcinovic
authors.forename: Andrea
authors.initials: A
authors.lastname: Saracevic
authors.forename: Ana
authors.initials: A
authors.lastname: Bakliza
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Simundic
mesh_terms: D000925:Anticoagulants / Q000737:chemistry / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis*; D001800:Blood Specimen Collection / Q000295:instrumentation; D019343:Citric Acid / Q000737:chemistry* / Q000494:pharmacology; D003920:Diabetes Mellitus / Q000175:diagnosis*; D005260:Female; D006019:Glycolysis / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006493:Heparin / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008297:Male; D019815:Oxalic Acid / Q000737:chemistry / Q000494:pharmacology; D012969:Sodium Fluoride / Q000737:chemistry / Q000494:pharmacology; D013696:Temperature
chemical_list: D000925:Anticoagulants; D001786:Blood Glucose; D019343:Citric Acid; D012969:Sodium Fluoride; D006493:Heparin; D019815:Oxalic Acid