Determination of cortisol production rates with contemporary liquid chromatography-mass spectrometry to measure cortisol-d3 dilution after infusion of deuterated tracer

Bethany J. Klopfenstein, Jonathan Q. Purnell, David D. Brandon, Lorne M. Isabelle, Andrea E. DeBarber

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Objectives: Measurement of 24-h cortisol production rate (CPR) using steady-state infusion of deuterated cortisol and analysis of stable-isotope dilution by MS is a valuable tool to examine hypothalamic-pituitary-adrenal axis activity in humans. We have developed and validated an improved method for measuring cortisol dilution with contemporary LC-MS technology. Design and methods: Plasma samples and calibrators were extracted with ethylacetate. LC-MS was performed with a Surveyor HPLC and TSQ Quantum triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) source. Results: Selectivity was improved over previous methods via elimination of an interferent identified as 20β-dihydrocortisol. The LLOQ for cortisol-d3 was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d3, with correlation coefficients >0.995. Conclusions: This APCI LC-MS method offers simplified sample work-up and analysis and enables selective detection of the low concentration of cortisol-d3 infused for determination of 24-h CPR.

Original languageEnglish (US)
Pages (from-to)430-434
Number of pages5
JournalClinical Biochemistry
Volume44
Issue number5-6
DOIs
StatePublished - Apr 2011

Keywords

  • 20β-Dihydrocortisol
  • Atmospheric pressure chemical ionization
  • Cortisol production rate
  • Liquid chromatography-mass spectrometry
  • Plasma

ASJC Scopus subject areas

  • Clinical Biochemistry

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