Rapid measurement of estrogens and their metabolites in human serum by liquid chromatography-tandem mass spectrometry without derivatization

Objectives: The steroids estradiol (E2), estrone (E1), and estriol (E3) are the major estrogens. E1/E2 and their metabolite 16-hydroxyestrone (16-OHE1, known to be carcinogenic) could be involved in the development of many cancers including human breast cancer. The aim of the current study was to develop a rapid and simple high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay to simultaneously measure E1, E2, E3 and 16-OHE1 in human serum without the need for solid phase extraction or derivatization. Methods: An API-5000 triple-quadrupole mass spectrometer coupled with electrospray ionization (ESI) source and Shimadzu HPLC system was used employing isotope dilution with deuterium-labeled internal standard (IS) for each analyte. Quantitation by multiple reaction monitoring (MRM) analysis was performed in negative ion mode. Results: The limits of detection were 1.0 pg/mL for E1 and 16-OHE1 and 2.0 pg/mL for E2 and E3. Within-day CVs were < 6.5% for all analytes tested and between-day CVs ranged from 4.5% to 9.5%. Recovery ranged from 88% to 108%. Conclusion: This method allows for the simultaneous measurement of four estrogens in human serum within 8 min. It can be routinely employed in a clinical environment and is attractive because of its simplicity in sample processing, micro sample requirement, and high throughput.