title: Effects of vigorous mixing of blood vacuum tubes on laboratory test results.
abstract: OBJECTIVE
  To evaluate the effect of tubes mixing (gentle vs. vigorous) on diagnostic blood specimens collected in vacuum tube systems by venipuncture.
  
  
  METHODS
  Blood was collected for routine coagulation, immunochemistry and hematological testing from one hundred volunteers into six vacuum tubes: two 3.6 mL vacuum tubes containing 0.4 mL of buffered sodium citrate (9NC) 0.109 mol/L: 3.2 W/V%; two 3.5 mL vacuum tubes with clot activator and gel separator; and two 3.0 mL vacuum tubes containing 5.9 mg K(2)EDTA (Terumo Europe, Belgium). Immediately after the venipuncture all vacuum tubes (each of one additive type) were processed through two different procedures: i) Standard: blood specimens in K(2)EDTA- or sodium citrate-vacuum tubes were gently inverted five times whereas the specimens in tubes with clot activator and gel separator were gently inverted ten times, as recommended by the manufacturer; ii) Vigorous mix: all blood specimens were shaken up vigorously during 3-5s independently of the additive type inside the tubes. The significance of the differences between samples was assessed by Student's t-test or Wilcoxon ranked-pairs test after checking for normality. The level of statistical significance was set at P<0.05.
  
  
  RESULTS
  No significant difference (P<0.05) was detected between the procedures for all tested parameters. Surprisingly only a visual alteration (presence of foam on the top) was shown by all the tubes mixed vigorously before centrifugation (Fig. 1 A, B and C). Moreover the serum tubes from vigorous mixing procedure shows a "blood ring" on the tube top after stopper removal (Fig. 1 D).
  
  
  CONCLUSIONS
  Our results drop out a paradigm suggesting that the incorrect primary blood tubes mixing promotes laboratory variability. We suggest that similar evaluation should be done using other brands of vacuum tubes by each laboratory manager.
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Italy. dr.g.lima.oliveira@gmail.com
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lima-Oliveira
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Salvagno
authors.forename: Martina
authors.initials: M
authors.lastname: Montagnana
authors.forename: Matteo
authors.initials: M
authors.lastname: Gelati
authors.forename: Waldemar
authors.initials: W
authors.lastname: Volanski
authors.forename: Katia Cristina
authors.initials: KC
authors.lastname: Boritiza
authors.forename: Geraldo
authors.initials: G
authors.lastname: Picheth
authors.forename: Gian Cesare
authors.initials: GC
authors.lastname: Guidi
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001800:Blood Specimen Collection / Q000379:methods*; D002021:Buffers; D002498:Centrifugation; D002951:Citrates / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D005260:Female; D006801:Humans; D007120:Immunochemistry; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D018962:Phlebotomy / Q000295:instrumentation*; D015203:Reproducibility of Results; D000077559:Sodium Citrate; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002021:Buffers; D002951:Citrates; D000077559:Sodium Citrate; D004492:Edetic Acid; D007770:L-Lactate Dehydrogenase; D000469:Alkaline Phosphatase