Stability of 15 estrogens and estrogen metabolites in urine samples under processing and storage conditions typically used in epidemiologic studies.
The International Journal of Biological Markers
PubMed Central® ID
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.
Ascorbic acid, epidemiologic methods, estrenes, estrogens, premenopause, preservation, biological, temperature, time factors
Fuhrman, Barbara J.; Xu, Xia; Falk, Roni T.; Hankinson, Susan E.; Veenstra, Timothy D.; Keefer, Larry K.; and Ziegler, Regina G., "Stability of 15 estrogens and estrogen metabolites in urine samples under processing and storage conditions typically used in epidemiologic studies." (2010). Pharmaceutical Sciences Faculty Publications. 262.