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Mark M Kushnir - One of the best experts on this subject based on the ideXlab platform.
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comparison of 7 published lc ms ms methods for the simultaneous measurement of testosterone Androstenedione and dehydroepiandrosterone in serum
Clinical Chemistry, 2015Co-Authors: Rahel M Buttler, Mark M Kushnir, Frans Martens, Flaminia Fanelli, Hai T Pham, Marcel J W Janssen, Laura Owen, Angela E Taylor, Tue SoeborgAbstract:BACKGROUND: Recently, LC-MS/MS was stated to be the method of choice to measure sex steroids. Because information on the mutual agreement of LC-MS/MS methods is scarce, we compared 7 published LC-MS/MS methods for the simultaneous measurement of testosterone, Androstenedione, and dehydroepiandrosterone (DHEA). METHODS: We used 7 published LC-MS/MS methods to analyze in duplicate 55 random samples from both men and women. We performed Passing–Bablok regression analysis and calculated Pearson correlation coefficients to assess the agreement of the methods investigated with the median concentration measured by all methods, and we calculated the intraassay CV of each method derived from duplicate results and the CVs between the methods. RESULTS: Median concentrations of testosterone were 0.22–1.36 nmol/L for women and 8.27–27.98 nmol/L for men. Androstenedione and DHEA concentrations were 0.05–5.53 and 0.58–18.04 nmol/L, respectively. Intraassay CVs were 2.9%–10%, 1.2%–8.8%, 2.7%–13%, and 4.3%–16% for testosterone in women, testosterone in men, Androstenedione, and DHEA. Slopes of the regression lines calculated by Passing–Bablok regression analysis were 0.92–1.08, 0.92–1.08, 0.90–1.13, and 0.91–1.41 for all testosterone values, testosterone in women, Androstenedione, and DHEA. Intermethod CVs were 14%, 8%, 30%, and 22% for testosterone in women, testosterone in men, Androstenedione, and DHEA. CONCLUSIONS: In general, the LC-MS/MS methods investigated show reasonable agreement. However, some of the assays show differences in standardization, and others show high variation.
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simultaneous measurement of testosterone Androstenedione and dehydroepiandrosterone dhea in serum and plasma using isotope dilution 2 dimension ultra high performance liquid chromatography tandem mass spectrometry id lc ms ms
Clinica Chimica Acta, 2015Co-Authors: Rahel M Buttler, Mark M Kushnir, Frans Martens, Mariette T Ackermans, M A Blankenstein, Annemieke C HeijboerAbstract:The adrenal and gonadal androgens, testosterone, Androstenedione and dehydroepiandrosterone (DHEA) play an important role in sexual development as well as in other processes. We developed a method for simultaneous quantitative analysis of serum and plasma testosterone, Androstenedione and DHEA levels using Isotope-Dilution Liquid-Chromatography Tandem Mass Spectrometry (ID-LC-MS/MS). Samples underwent liquid-liquid extraction and were analyzed on an Acquity 2D-UPLC-System and a Xevo TQ-S tandem mass spectrometer (Waters). The intra-assay and inter-assay coefficients of variation were <4.0%, <6.3% and <7.0% and <6.0%, <8.1% and <7.7% for testosterone, Androstenedione and DHEA, respectively. Inter-assay CVs at the lower limit were 10.6%, 16.9% and 9.0% for testosterone (0.10nmol/L), Androstenedione (0.10nmol/L) and DHEA (1.0nmol/L), respectively. Recoveries of spiked analytes were 93-107%. The present testosterone method compared well (y=1.00x-0.04; r=0.998) to a published ID-LC-MS/MS method for testosterone in our lab. The latter method being concordant with a published reference method (Bui et al., 2013). The present method compared well to a published ID-LC-MS/MS method (Kushnir et al., 2010) (y=1.06x-0.06; r=0.996 for testosterone; y=1.04x-0.04; r=0.995 for Androstenedione and y=1.03x+0.01; r=0.991 for DHEA). In conclusion, we developed a sensitive and accurate ID-LC-MS/MS method to simultaneously measure serum testosterone, Androstenedione and DHEA in serum and plasma.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Ashley M Bunker, Wayne A MeikleAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Bingfang Yue, Ashley M BunkerAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
Alan L Rockwood - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Ashley M Bunker, Wayne A MeikleAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Bingfang Yue, Ashley M BunkerAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
William L Roberts - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Ashley M Bunker, Wayne A MeikleAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Bingfang Yue, Ashley M BunkerAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
Ashley M Bunker - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Ashley M Bunker, Wayne A MeikleAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
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liquid chromatography tandem mass spectrometry assay for Androstenedione dehydroepiandrosterone and testosterone with pediatric and adult reference intervals
Clinical Chemistry, 2010Co-Authors: Mark M Kushnir, Takara Blamires, Alan L Rockwood, William L Roberts, Evrim Erdogan, Bingfang Yue, Ashley M BunkerAbstract:Background: Measurement of serum androgens is important in adult, geriatric, pediatric endocrinology, and oncology patients. We developed a liquid chromatography—tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of Androstenedione, dehydroepiandrosterone (DHEA), and testosterone in these patients. Methods: We spiked 200 μL of serum or plasma with isotope-labeled internal standards and performed extraction with methyl t-butyl ether. We then derivatized the extracts with hydroxylamine and analyzed them by LC-MS/MS using a 2-dimensional chromatographic separation with a 3.5-min analysis time. Results: Total imprecision for each analyte was <11.2%. Limits of quantification were 10, 50, and 10 ng/L for Androstenedione, DHEA, and testosterone, respectively. Reference intervals were established for children (age 6 months to 17 years), men, and women. Androstenedione and DHEA concentrations were lowest in 2- to 3-year-old children. Adult concentrations were achieved in girls at Tanner stage 3 and in boys at Tanner stage 4–5. In premenopausal and (postmenopausal) women the median concentrations of Androstenedione, DHEA, and testosterone were 810 (360), 3000 (1670), 270 (180) ng/L, respectively. In postmenopausal women, concentrations of testosterone were age independent, whereas Androstenedione and DHEA concentrations decreased with age. In men the median concentrations of Androstenedione, DHEA, and testosterone were 440, 2000, and 3700 ng/L, respectively. In men older than 40 years, median concentrations decreased at rates of 5%, 10%, and 20% per decade for Androstenedione, DHEA, and testosterone, respectively. Conclusions: This LC-MS/MS method has the required lower limit of quantification and specificity for analysis of endogenous concentrations of androgens in all groups studied. Reference intervals were established for healthy children and adults.
Amitabh Krishna - One of the best experts on this subject based on the ideXlab platform.
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mechanism for delayed ovulation in a tropical vespertilionid bat,
2016Co-Authors: Scotophilus Heathi, Amitabh KrishnaAbstract:The steroid hormone profile of Scotophilus heathi, an Indian tropical vespertilionid bat, was studied, with special reference to the period of delayed ovulation. The results show unusually high concentrations of circulating Androstenedione and testosterone during the first half of the period of delayed ovulation, whereas the concentrations of progesterone and oestradiol were relatively low during this period. Androstenedione, testosterone and oestradiol concentrations were high during the period of ovarian recrudescence (October\p=n-\ November). The oestradiol concentration increased, whereas Androstenedione and testos-terone declined significantly, before ovulation. Studies in vitro showed that the ovary secretes more Androstenedione and testosterone than does the adrenal. A histological study showed that a major part of the ovary of S. heathi was occupied by hypertrophied interstitial cells. An immunocytochemical study showed ovarian thecal interstitial cells as the major site of high androgen synthesis in the ovary. During the period of delayed ovulation the bat ovaries thus resemble the ovaries from women with polycystic ovaries in which abnormally high androgen secretion from hypertrophied interstitial cells prevent ovulation
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high androgen production by ovarian thecal interstitial cells a mechanism for delayed ovulation in a tropical vespertilionid bat scotophilus heathi
Reproduction, 1996Co-Authors: Amitabh KrishnaAbstract:The steroid hormone profile of Scotophilus heathi, an Indian tropical vespertilionid bat, was studied, with special reference to the period of delayed ovulation. The results show unusually high concentrations of circulating Androstenedione and testosterone during the first half of the period of delayed ovulation, whereas the concentrations of progesterone and oestradiol were relatively low during this period. Androstenedione, testosterone and oestradiol concentrations were high during the period of ovarian recrudescence (October-November). The oestradiol concentration increased, whereas Androstenedione and testosterone declined significantly, before ovulation. Studies in vitro showed that the ovary secretes more Androstenedione and testosterone than does the adrenal. A histological study showed that a major part of the ovary of S. heathi was occupied by hypertrophied interstitial cells. An immunocytochemical study showed ovarian thecal interstitial cells as the major site of high androgen synthesis in the ovary. During the period of delayed ovulation the bat ovaries thus resemble the ovaries from women with polycystic ovaries in which abnormally high androgen secretion from hypertrophied interstitial cells prevent ovulation.