Assay reproducibility and interindividual variation for 15 serum estrogens and estrogen metabolites measured by liquid chromatography-tandem mass spectrometry

Barbara J. Fuhrman*, Xia Xu, Roni T. Falk, Cher M. Dallal, Timothy D. Veenstra, Larry K. Keefer, Barry I. Graubard, Louise A. Brinton, Regina G. Ziegler, Gretchen L. Gierach

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Background: Interindividual differences in estrogen metabolism may partially account for differences in risks of estrogen-responsive cancers. We conductedaproof-of-performance study toassess the reproducibility of a LC/MS-MS method for measurement of 15 serum estrogens and metabolites (all 15 termed EM) in total (conjugated+unconjugated) and unconjugated forms and describe interindividual variation.

Methods: Interindividual variation in serum EM profiles was evaluated for 20 premenopausal women, 15 postmenopausal women, and 10 men. Replicate aliquots from 10 premenopausal women, 5 postmenopausal women, and 5 men were assayed eight times over 4 weeks. Components of variance were used to calculate coefficients of variation (CV) and intraclass correlation coefficients (ICC).

Results: In postmenopausal women and men, median EM concentrations were similar and substantially lower than that in premenopausal women. Within each sex/menopausal group, the sum of all EM varied 5-to 7-fold across extreme deciles. Some EM had greater variation; total estrone varied approximately 12-fold in premenopausal and postmenopausal women. Unconjugated estradiol varied 17-fold in postmenopausal women but only 5-fold in premenopausal women and men. CVs reflecting variation across replicate measures for individuals were <5% for most EM, but higher in some individuals with a low EM concentration. Overall laboratory CVs for all but one EM were <2% and ICCs were >99% for all EM in each group.

Conclusions: The serum EM assay has excellent laboratory reproducibility. In premenopausal women, postmenopausal women, and men, interindividual variation in EM measures is substantially greater than laboratory variation.

Impact: The serum EM assay is suitable for epidemiologic application.

Original languageEnglish
Pages (from-to)2649-2657
Number of pages9
JournalCancer Epidemiology Biomarkers and Prevention
Volume23
Issue number12
DOIs
StatePublished - 1 Dec 2014
Externally publishedYes

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