Pharmaceutical Sciences Faculty Publications
Quantitative Measurement of Endogenous Estrogens and Estrogen Metabolites in Human Serum by Liquid Chromatography-Tandem Mass Spectrometry
Document Type
Article
Publication Date
10-15-2007
Journal Title
Analytical Chemistry
ISSN
0003-2700
Volume
79
Issue
20
First Page
7813
Last Page
7821
DOI
10.1021/ac070494j
PubMed ID
17848096
Abstract
Endogenous estrogen plays a key role in the development of human breast cancer, yet the contribution of specific estrogen metabolites and patterns of estrogen metabolism remains unclear. To determine their individual and joint roles in breast carcinogenesis, it is necessary to be able to measure quantitatively each estrogen metabolite in epidemiologic and clinical biospecimens. In this report, we detail a sensitive, specific, accurate, and precise high-performance liquid chromatography-tandem mass spectrometry method utilizing selected reaction monitoring for measuring the absolute quantities of free (unconjugated) and total (conjugated + unconjugated) endogenous estrogens and estrogen metabolites in human serum from premenopausal and postmenopausal women. The method requires a simple sample preparation and only 0.5 mL of serum, yet is capable of quantifying simultaneously 15 estrogens and estrogen metabolites (EM): estrone and its 2-, 4-, and 16alpha-hydroxy and 2- and 4-methoxy derivatives; 2-hydroxyestrone-3-methyl ether; 17beta-estradiol and its 2-hydroxy and 2- and 4-methoxy derivatives; and estriol, 17-epiestriol, 16-ketoestradiol, and 16-epiestriol. The lower limit of quantitation for each EM was 0.4 pg on-column, equivalent to 8 pg/mL (26.5-29.6 fmol/mL) in the original serum sample. Calibration curves were linear over a 10(3)-fold concentration range. For a stripped serum sample containing 8 pg/mL of each EM, accuracy (percent recovery of a known added amount) ranged from 91 to 113%. Intrabatch precision (including hydrolysis, extraction, and derivatization steps) ranged from 7 to 30% relative standard deviation (RSD), and interbatch precision ranged from 8 to 29% RSD. Since distinct roles have been proposed for many of these estrogen metabolites, an accurate, precise, sensitive, and specific method for measuring their levels in circulation should suggest new approaches to breast cancer prevention, screening, and treatment.
Keywords
Chromatography, high pressure liquid, estrogens, hydrolysis, ions, spectrometry, mass, electrospray ionization
Recommended Citation
Xu, Xia; Roman, John M.; Issaq, Haleem J.; Keefer, Larry K.; Veenstra, Timothy D.; and Ziegler, Regina G., "Quantitative Measurement of Endogenous Estrogens and Estrogen Metabolites in Human Serum by Liquid Chromatography-Tandem Mass Spectrometry" (2007). Pharmaceutical Sciences Faculty Publications. 355.
https://digitalcommons.cedarville.edu/pharmaceutical_sciences_publications/355