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Effect of order of draw of blood samples during phlebotomy on routine biochemistry results
  1. Raashda A Sulaiman1,
  2. Michael P Cornes1,
  3. Simon J Whitehead1,
  4. Nadia Othonos1,
  5. Clare Ford1,
  6. Rousseau Gama1,2
  1. 1Department of Clinical Chemistry, New Cross Hospital, Wolverhampton, West Midlands, UK
  2. 2Research Institute, Healthcare Sciences, Wolverhampton University, Wolverhampton, West Midlands, UK
  1. Correspondence to Dr Raashda Sulaiman, Department of Clinical Biochemistry, University Hospitals Birmingham, Raddle Barn Lane, Birmingham B29 6JD, UK; raashda3{at}


Aim To investigate whether incorrect order of draw of blood samples during phlebotomy causes in vitro potassium ethylenediaminetetraacetic acid EDTA (kEDTA) contamination of blood samples.

Methods Serum kEDTA, potassium, calcium, magnesium, alkaline phosphatase, zinc and iron concentrations were measured in blood samples drawn before and after collecting blood into kEDTA containing sample tubes by an experienced phlebotomist using the Sarstedt Safety Monovette system.

Results EDTA was undetectable in all samples. The concentrations of other analytes were similar in blood samples drawn before and after collection of the EDTA blood sample.

Conclusion Order of draw of blood samples using the Sarstedt Safety Monovette system has no effect on serum biochemistry results, when samples are taken by an experienced phlebotomist.

  • Order of draw
  • EDTA contamination
  • hyperkalaemia
  • hypocalcaemia
  • biochemistryelectrolytes
  • metabolism
  • laboratory tests
  • laboratory management
  • chemical pathology
  • education
  • endocrinology
  • entero-insular axis
  • cardiovascular
  • hypoglycaemia
  • thyroid endocrinology

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  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Coventry and Warwickshire Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.