Pharmaceutical Sciences Faculty Publications

Assay Reproducibility and Interindividual Variation for 15 Serum Estrogens and Estrogen Metabolites Measured by Liquid Chromatography-Tandem Mass Spectrometry

Document Type

Article

Publication Date

11-30-2014

Journal Title

Cancer Epidemiology, Biomarkers & Prevention

ISSN

1538-7755

Volume

23

Issue

12

First Page

2649

Last Page

2657

DOI

10.1158/1055-9965.EPI-14-0438

PubMed ID

25472673

Abstract

BACKGROUND: Interindividual differences in estrogen metabolism may partially account for differences in risks of estrogen-responsive cancers. We conducted a proof-of-performance study to assess 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 were99% 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. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Keywords

Chromatography, liquid, estrogens, postmenopause, premenopause, tandem mass spectrometry

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