Comparison of Methods to Measure Low Serum Estradiol Levels in Postmenopausal Women Export

@article{citeulike:4079668, abstract = {Context: Accurate measurement of low serum estradiol (E2 < 30 pg/ml or < 110 pmol/liter) is needed to study relationships between endogenous E2 and risks of diseases in older women. Objective: The objective of this study was to determine whether an extraction-based (indirect) assay or a non-extraction-based (direct) assay correlates better with mass spectrometry and body mass index (BMI). Design/Setting: In a pilot study of 40 postmenopausal women, endogenous E2 measurements from three indirect and four direct assay methods and gas chromatography-tandem mass spectrometry (GC-MS/MS) were compared. A confirmatory study compared an indirect and a direct assay, selected among those in the pilot study, to GC-MS/MS; this study was conducted in 374 postmenopausal women not taking hormone therapy from the Ultra Low-dose TRansdermal estrogen Assessment (ULTRA) trial. Main Outcomes: Pearson correlation coefficients among E2 measurements by assay methods and BMI, and their confidence intervals, by bias-corrected bootstrap method, were used. Results: In the pilot study, E2 by three indirect assays correlated better (P < 0.03) with GC-MS/MS and with BMI than measurements by four direct assays. In the confirmatory study, the indirect assay correlated better (P < 0.01) with GC-MS/MS and BMI than the direct assay. Measurements by the indirect and direct assays were overestimated, but deviations in direct assay measurements were less precise. Mean E2 by the indirect and direct assays were higher (by 14 and 68\%, respectively) and less reproducible than by GC-MS/MS. Conclusion: Until mass spectrometry is practical for wide use, extraction-based indirect assays may be preferable for measuring low postmenopausal serum E2. 10.1210/jc.2005-2378}, author = {Lee, Jennifer S. and Ettinger, Bruce and Stanczyk, Frank Z. and Vittinghoff, Eric and Hanes, Vladimir and Cauley, Jane A. and Chandler, Walt and Settlage, Jim and Beattie, Mary S. and Folkerd, Elizabeth and Dowsett, Mitch and Grady, Deborah and Cummings, Steven R.}, citeulike-article-id = {4079668}, citeulike-linkout-0 = {http://dx.doi.org/10.1210/jc.2005-2378}, citeulike-linkout-1 = {http://jcem.endojournals.org/cgi/content/abstract/91/10/3791}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/16882749}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=16882749}, day = {1}, doi = {10.1210/jc.2005-2378}, journal = {J Clin Endocrinol Metab}, keywords = {comparison, estradiol, estrogen, low-level, measurement, new-assay, postmenopausal}, month = {October}, number = {10}, pages = {3791--3797}, posted-at = {2009-02-22 12:09:06}, priority = {2}, title = {Comparison of Methods to Measure Low Serum Estradiol Levels in Postmenopausal Women}, url = {http://dx.doi.org/10.1210/jc.2005-2378}, volume = {91}, year = {2006} }

TY - JOUR ID - citeulike:4079668 L3 - citeulike-article-id:4079668 N2 - Context: Accurate measurement of low serum estradiol (E2 < 30 pg/ml or < 110 pmol/liter) is needed to study relationships between endogenous E2 and risks of diseases in older women. Objective: The objective of this study was to determine whether an extraction-based (indirect) assay or a non-extraction-based (direct) assay correlates better with mass spectrometry and body mass index (BMI). Design/Setting: In a pilot study of 40 postmenopausal women, endogenous E2 measurements from three indirect and four direct assay methods and gas chromatography-tandem mass spectrometry (GC-MS/MS) were compared. A confirmatory study compared an indirect and a direct assay, selected among those in the pilot study, to GC-MS/MS; this study was conducted in 374 postmenopausal women not taking hormone therapy from the Ultra Low-dose TRansdermal estrogen Assessment (ULTRA) trial. Main Outcomes: Pearson correlation coefficients among E2 measurements by assay methods and BMI, and their confidence intervals, by bias-corrected bootstrap method, were used. Results: In the pilot study, E2 by three indirect assays correlated better (P < 0.03) with GC-MS/MS and with BMI than measurements by four direct assays. In the confirmatory study, the indirect assay correlated better (P < 0.01) with GC-MS/MS and BMI than the direct assay. Measurements by the indirect and direct assays were overestimated, but deviations in direct assay measurements were less precise. Mean E2 by the indirect and direct assays were higher (by 14 and 68%, respectively) and less reproducible than by GC-MS/MS. Conclusion: Until mass spectrometry is practical for wide use, extraction-based indirect assays may be preferable for measuring low postmenopausal serum E2. 10.1210/jc.2005-2378 IS - 10 JF - J Clin Endocrinol Metab EP - 3797 TI - Comparison of Methods to Measure Low Serum Estradiol Levels in Postmenopausal Women VL - 91 SP - 3791 KW - comparison KW - estradiol KW - estrogen KW - low-level KW - measurement KW - new-assay KW - postmenopausal AU - Lee, Jennifer AU - Ettinger, Bruce AU - Stanczyk, Frank AU - Vittinghoff, Eric AU - Hanes, Vladimir AU - Cauley, Jane AU - Chandler, Walt AU - Settlage, Jim AU - Beattie, Mary AU - Folkerd, Elizabeth AU - Dowsett, Mitch AU - Grady, Deborah AU - Cummings, Steven PY - 2006/10/01/ UR - http://dx.doi.org/10.1210/jc.2005-2378 ER -