title: Comparison of eight routine unpublished LC-MS/MS methods for the simultaneous measurement of testosterone and androstenedione in serum.
abstract: BACKGROUND
  Liquid-chromatography tandem mass spectrometry (LC-MS/MS) has become the method of choice in steroid hormone measurement. However, little information on the mutual agreement of LC-MS/MS methods is available. We compared eight routine unpublished LC-MS/MS methods for the simultaneous measurement of testosterone and androstenedione.
  
  
  METHODS
  Sixty random serum samples from male and female volunteers were analysed in duplicate by eight routine LC-MS/MS methods. We performed Passing-Bablok regression analyses and calculated Pearson's correlation coefficients to assess the agreement of the methods investigated with one published method known to be accurate. Intra-assay CV of each method was calculated from duplicate results, recoveries for each method were calculated from six spiked samples. Furthermore, a CV between the investigated methods was calculated.
  
  
  RESULTS
  The concentrations ranged from 0.05-1.26 nmol/L, 6.15-24.44 nmol/L and 0.15-4.78 nmol/L for testosterone in females, testosterone in males and androstenedione, respectively. The intra-assay CVs were between 3.7-16.0%, 0.9-5.2% and 1.2-9.5% for testosterone in females, testosterone in males and androstenedione, respectively. The slopes of the regression lines ranged between 0.90-1.25, 0.87-1.24 and 0.94-1.31 for testosterone concentrations in females, all testosterone values and androstenedione, respectively. Inter-method CVs were 24%, 14% and 29% for testosterone for concentrations in females and males and androstenedione, respectively. These compare unfavourably to the variation found earlier in published methods.
  
  
  CONCLUSIONS
  Although most routine LC-MS/MS methods investigated here showed a reasonable agreement, some of the assays showed a high variation. The observed differences in standardization should be taken into account when applying reference values, or should, preferably, be solved.
authors.affiliation: Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Rahel M
authors.initials: RM
authors.lastname: Büttler
authors.affiliation: Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: Martens
authors.affiliation: Department of Clinical Chemistry, Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Mariëtte T
authors.initials: MT
authors.lastname: Ackermans
authors.affiliation: Department of Clinical Biochemistry and Metabolic Medicine, Liverpool Clinical Laboratories, Royal Liverpool and Broadgreen University Hospitals Trust, Liverpool, United Kingdom.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Davison
authors.affiliation: Department of Laboratory Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Antonius E
authors.initials: AE
authors.lastname: van Herwaarden
authors.affiliation: MVZ wagnerstibbe für Laboratoriumsmedizin, Gynäkologie, Humangenetik und Pathologie GmbH, Göttingen, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Kortz
authors.affiliation: Department of Clinical Chemistry and Laboratory Medicine, Medical Spectrum Twente, Medlon BV, The Netherlands.
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Krabbe
authors.affiliation: Department of Clinical Chemistry & Haematology, University Medical Center, Utrecht, The Netherlands.
authors.forename: Eef G W
authors.initials: EG
authors.lastname: Lentjes
authors.affiliation: Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Syme
authors.affiliation: Department of Clinical Biochemistry, University Hospitals Birmingham NHS Foundation Trust Queen Elizabeth Hospital, Birmingham, United Kingdom.
authors.forename: Rachel
authors.initials: R
authors.lastname: Webster
authors.affiliation: Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Blankenstein
authors.affiliation: Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: a.heijboer@vumc.nl.
authors.forename: Annemieke C
authors.initials: AC
authors.lastname: Heijboer
mesh_terms: D000328:Adult; D000735:Androstenedione / Q000097:blood*; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D008297:Male; D012044:Regression Analysis; D053719:Tandem Mass Spectrometry; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D000735:Androstenedione
keywords: Androgens; Androstenedione; LC–MS/MS; Method comparison; Steroid hormones; Testosterone