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-d(3) was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d(3), 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-d(3) infused for determination of 24-h CPR.
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-d(3) was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d(3), 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-d(3) infused for determination of 24-h CPR.
Authors: Ileana A Ionita; Douglas M Fast; Fatemeh Akhlaghi Journal: J Chromatogr B Analyt Technol Biomed Life Sci Date: 2009-02-11 Impact factor: 3.205
Authors: Lynnette K Nieman; Beverly M K Biller; James W Findling; M Hassan Murad; John Newell-Price; Martin O Savage; Antoine Tabarin Journal: J Clin Endocrinol Metab Date: 2015-07-29 Impact factor: 5.958
Authors: Kevin C J Yuen; Charles T Roberts; Jan Frystyk; William D Rooney; James R Pollaro; Bethany J Klopfenstein; Jonathan Q Purnell Journal: J Clin Endocrinol Metab Date: 2014-07-11 Impact factor: 5.958