Pharmaceutical Sciences Faculty Publications

Title

Stability of 15 estrogens and estrogen metabolites in urine samples under processing and storage conditions typically used in epidemiologic studies.

Document Type

Article

Publication Date

10-1-2010

Journal Title

The International Journal of Biological Markers

ISSN

1724-6008

Volume

25

Issue

4

First Page

185

Last Page

194

PubMed ID

21161939

PubMed Central® ID

PMC3131741

Abstract

BACKGROUND: In preparation for large-scale epidemiologic studies of the role of estrogen metabolism in the etiology of breast and other cancers, we examined the stability of estrogens and estrogen metabolites (EM) in urine during processing and storage protocols.

METHODS: Fifteen EM were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in first morning urines from 3 premenopausal women. Linear regression was used to model log EM concentrations for each woman, with and without adding ascorbic acid (0.1% w/v), during storage at 4°C (7-8 time points, up to 48 hours), during long-term storage at -80°C (10 time points, up to 1 year), and by freeze-thaw cycles (up to 3).

RESULTS: Without ascorbic acid, concentrations (pmol/mL) of nearly all EM changed

CONCLUSIONS: Given the large inter-individual variability in urinary EM concentrations, changes of the magnitude observed here are unlikely to cause substantial misclassification. Furthermore, processing and storage conditions studied here are adequate for use in epidemiologic studies.

Keywords

Ascorbic acid, epidemiologic methods, estrenes, estrogens, premenopause, preservation, biological, temperature, time factors

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