title: Influence of separator gel in Sarstedt S-Monovette® serum tubes on various therapeutic drugs, hormones, and proteins.
abstract: BACKGROUND
  A separator or barrier gel is a common component of serum and plasma collection tubes. Despite their advantages, the use of these tubes is not universally accepted, especially for therapeutic drug monitoring (TDM). The aim of this study was to evaluate whether the polyacrylester separator gel in Sarstedt S-Monovette\® tubes influences the concentration of 10 selected parameters (amikacin, vancomycin, valproic acid, acetaminophen, cortisol, free thyroxine, thyroid-stimulating hormone, transferrin, prealbumin and carcinoembryonic antigen) in a clinically significant way.
  
  
  METHODS
  Results from patient samples collected in plastic Sarstedt S-Monovette® tubes with separator gel were compared with those from plain serum sample tubes. Analytes were measured in both tubes on 4 consecutive days to study the influence of prolonged contact with the separator gel. Between analyses tubes were stored at 4°C. Stability was also evaluated over 72 h for each collection tube. When statistical differences were detected, the clinical significance was evaluated based on the total allowable error (TEa).
  
  
  RESULTS
  On day 1 no statistically significant differences were observed between samples collected in Sarstedt S-Monovette® tubes with and without separator gel. Statistical differences were present from day 2 on, but were not clinically significant. All evaluated parameters were clinically stable over 72 h at 4°C based on TEa, except for transferrin en fT4.
  
  
  CONCLUSIONS
  The separator gel in Sarstedt S-Monovette® tubes did not show statistically significant differences on the day of phlebotomy. Later on statistically significant differences appeared but except for the stability of fT4 and transferrin they all remained clinically insignificant.
authors.affiliation: Laboratory for Clinical Chemistry and Toxicology, ZNA Stuivenberg, Antwerp, Belgium.
authors.forename: Sofie
authors.initials: S
authors.lastname: Schouwers
authors.forename: Inger
authors.initials: I
authors.lastname: Brandt
authors.forename: Johan
authors.initials: J
authors.lastname: Willemse
authors.forename: Niels
authors.initials: N
authors.lastname: Van Regenmortel
authors.forename: Wim
authors.initials: W
authors.lastname: Uyttenbroeck
authors.forename: Annick
authors.initials: A
authors.lastname: Wauters
authors.forename: Hugo
authors.initials: H
authors.lastname: Neels
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D006728:Hormones / Q000097:blood*; D006801:Humans; D004364:Pharmaceutical Preparations / Q000097:blood*; D013048:Specimen Handling
chemical_list: D001798:Blood Proteins; D006728:Hormones; D004364:Pharmaceutical Preparations