Quantitative analysis of 34 sex (pro)hormones, conjugates and bioactive oxidation products thereof in human plasma by GC- and LC-MS/MS and systematic investigation of overestimations of analyte concentrations not accounted for by method validation.
Miriam Raps, Carolin Kleider, Leane Lehmann
Author Information
Miriam Raps: University of W��rzburg, Chair of Food Chemistry, 97074 W��rzburg, Germany. Electronic address: miriam.raps@uni-wuerzburg.de.
Carolin Kleider: University of W��rzburg, Chair of Food Chemistry, 97074 W��rzburg, Germany. Electronic address: carolin.kleider@uni-wuerzburg.de.
Leane Lehmann: University of W��rzburg, Chair of Food Chemistry, 97074 W��rzburg, Germany. Electronic address: leane.lehmann@uni-wuerzburg.de.
When investigating endocrine disorders, it is essential to assess a comprehensive quantitative profile of sex (pro)hormones in plasma including conjugates. Thus, the present study aimed to develop and validate a comprehensive mass spectrometry-based multimethod combining the direct analysis of unconjugated sex (pro)hormones and oxidation products thereof (by GC), as well as their sulfates and glucuronides present in higher concentrations (by LC) with the indirect quantification of glucuronides present in lower concentrations after selective glucuronide hydrolysis (by GC) and its application to plasma derived from ten pre- and postmenopausal women and men each. Even guideline-compliant validation experiments cannot completely reflect overestimation of analyte concentrations due to effects depending on the individual ratio of analytes (i.e. chemical formation of analytes or incomplete removal of interfering analytes). Thus, the extent of processes not accounted for by the calibration strategy were investigated and maximum over- or underestimations of analyte concentrations were assessed for each plasma sample individually. 34 analytes were successfully calibrated, validated (median accuracy 101.1 %, median inter-day precision 8.1 %) and 31 were detected above the detection limit in plasma samples. The sporadic maximum individual over- or underestimation of analyte concentrations amounted to less than 20 %.