Measurement of estradiol, estrone, and testosterone in postmenopausal human serum by isotope dilution liquid chromatography tandem mass spectrometry without derivatization

Mimicking women's endocrine milieu in mice for women's health-related studies

To improve preclinical studies and their translation, patient-derived xenografts (PDXs) are increasingly used. They have human-specific tumor characteristics and reflect intra and inter-tumor heterogeneity. However, the endocrine milieu differs between humans and host mice. In light of sex-specific cancer biology and a rise in endocrine-related cancers there is an urgent need to correctly reflect the hormonal milieu in PDX models. We show that female mice of NOD.Cg-Prkdc scid Il2rg tm1Wjl /SzJ (NSG) strain widely used for PDXs has 17-β-estradiol (E2) and testosterone (T) levels comparable to C57Bl6 females but higher progesterone (P4) levels. E2 levels are comparable, T levels are lower and P4 levels higher than those observed in postmenopausal women. Ovariectomy increases T to levels observed in postmenopausal women. Subcutaneous E2 and combined E2/P4 silicon pellets provide NSG females with premenopausal ovarian hormone levels. These procedures humanize the endocrine environment of experimental animals, improving PDX relevance in women's health-related research.

Ultrasensitive Electrochemical Biosensor for Rapid Screening of Chemicals with Estrogenic Effect

Estrogenic chemicals are widely distributed and structurally diverse. They primarily disrupt estrogen-related metabolism in animals or humans by mimicking the agonistic receptor effects of natural estrogens, thereby influencing the transcription of estrogen receptors to regulate their quantity and sensitivity. This disruption of estrogen-related metabolism can lead to estrogen-related effects, posing risks to biological health, emphasizing the urgent need for simple and effective methods to screen compounds with estrogenic effects. Herein, a new electrochemical biological effect biosensor based on human estrogen receptor α (hERα) is developed, which uses hERα as the biorecognition element and employs the electroactive horseradish peroxidase (HRP) labeled 17β-estradiol (E2) multifunctional conjugate HRP-E2 as the signal-boosting element and ligand competition agent. Based on the specific ligand-receptor interaction principle between the target and nuclear receptor, by allowing the test compound to compete with HRP-E2 conjugate for binding to hERα and testing the electrocatalytic signal of the conjugate that fails to bind to the hERα estrogen receptor, rapid screening and quantitative detection of chemical substances with estrogenic effect have been achieved. The biosensor shows a wide linear range of 40 pM to 40 nM with a detection limit of 17 pM (S/N = 3) for E2, and the detection limit is 2 orders of magnitude better than that of the previously reported sensors. The biosensor based on ligand-receptor binding can not only quantitatively analyze the typical estrogen E2, but also evaluate the relative estrogen effect strength of other estrogen compounds, which has good stability and selectivity. This electrochemical sensing platform displays its promising potential for rapid screening and quantitative detection of chemicals with estrogenic effects.

Highly sensitive tandem mass spectrometric measurement of serum estradiol without derivatization and pediatric reference intervals in children and adolescents

OBJECTIVES

Monitoring estradiol (E2) is important for determining the onset of pubertal development as well as in the evaluation of girls with precocious puberty. However, E2 measurement remains an analytical challenge in children, who have lower circulating levels. We developed and evaluated a simple and sensitive LC-MS/MS procedure for serum E2 quantification in pediatric populations and established age- and sex-specific pediatric reference intervals.

METHODS

Residual patient serum samples were used to evaluate the analytical performance of our in-house LC-MS/MS E2 assay. The evaluation included accuracy, precision, linearity, functional sensitivity (LLoQ), and method comparison. Age- and sex-specific pediatric E2 reference intervals were also established from a cohort of 405 healthy children (birth to 18 years) recruited with informed consent. Age- and sex-specific differences were assessed, and outliers were removed. Reference intervals were established using the robust method.

RESULTS

The assay imprecision was <5.3 %. Assay linearity ranged from 13.7 to 1923.3 pmol/L. The LLoQ corresponding to a CV of 20 % was determined to be 8.9 pmol/L. Bland-Altman analysis revealed a mean bias of 29.3 pmol/L or 9.1 % between our LC-MS/MS E2 assay and an external reference laboratory measuring E2 by LC-MS/MS.

CONCLUSIONS

Our LC-MS/MS E2 assay shows acceptable accuracy, precision, functional sensitivity (LLoQ), and linearity for E2 quantification. Our LC-MS/MS E2 assay also showed good agreement with an external reference laboratory measuring E2 by LC-MS/MS. In addition, using CALIPER samples, we established robust age- and sex-specific pediatric E2 reference intervals to improve accuracy of test result interpretation and clinical decision making.

Derivatized versus non-derivatized LC-MS/MS techniques for the analysis of estrogens and estrogen-like endocrine disruptors in human plasma

Bisphenols, parabens, alkylphenols and triclosan are anthropogenic substances with a phenolic group that have been introduced to the environment in recent decades. As they possess hormone-like effects, they have been termed endocrine disruptors (EDs), and can interfere with steroid pathways in organisms. To evaluate the potential impact of EDs on steroid biosynthesis and metabolism, sensitive and robust methods enabling the concurrent measurement of EDs and steroids in plasma are needed. Of crucial importance is the analysis of unconjugated EDs, which possess biological activity. The aim of the study was to develop and validate LC-MS/MS methods with and without a derivatization step for the analysis of unconjugated steroids (estrone-E1, estradiol-E2, estriol-E3, aldosterone-ALDO) and different groups of EDs (bisphenols, parabens, nonylphenol-NP and triclosan-TCS), and compare these methods on a set of 24 human plasma samples using Passing-Bablok regression analysis. Both methods were validated according to FDA and EMA guidelines. The method with dansyl chloride derivatization allowed 17 compounds to be measured: estrogens (E1, E2, E3), bisphenols (bisphenol A-BPA, BPS, BPF, BPAF, BPAP, BPZ, BPP), parabens (methylparaben-MP, ethylparaben-EP, propylparaben-PP, butylparaben-BP, benzylparaben-BenzylP), TCS and NP, with lower limits of quantification (LLOQs) between 4 and 125 pg/mL. The method without derivatization enabled 15 compounds to be analyzed: estrogens (E1, E2, E3), ALDO, bisphenols (BPA, BPS, BPF, BPAF, BPAP, BPZ), parabens (MP, EP, PP, BP, BenzylP) with LLOQs between 2 and 63 pg/mL, and NP and BPP in semiquantitative mode. Adding 6 mM ammonium fluoride post column into mobile phases in the method without derivatization achieved similar or even better LLOQs than the method with the derivatization step. The uniqueness of the methods lies in the simultaneous determination of different classes of unconjugated (bioactive) fraction of EDs together with selected steroids (estrogens + ALDO in the method without derivatization), which provides a useful tool for evaluating the relationships between EDs and steroid metabolism.

Analytical Performance Evaluation for Estradiol using Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

There is an increased need for the sensitive and accurate measurement of estradiol levels in patients with estradiol-related endocrine disorders. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a reliable and accurate method for measuring steroid hormone levels. Here, we aimed to establish an LC-MS/MS-based method to quantify estradiol levels without sample derivatization and evaluated its analytical performance.

METHODS

Sciex Triple Quad 6500 + LC-MS/MS was used for estradiol analysis. We evaluated its analytical performance, including linearity, precision, the lower limit of detection and quantification (LoD and LoQ, respectively), accuracy, and carryover. The estradiol results determined by LC-MS/MS were compared with those obtained using a chemiluminescent microparticle immunoassay.

RESULTS

The LC-MS/MS output was linear for serum estradiol concentrations in the range of 0.2-10311.6 pmol/L. The intra-laboratory precision (coefficient of variation) was 3.0-10.1 %. The LoD and LoQ were 2.8 and 7.5 pmol/L, respectively. The overall accuracy was within 15 % of bias, and the carryover was within the acceptable range (<1.0 %). The results of the estradiol analysis determined by LC-MS/MS were comparable to those obtained by the chemiluminescent microparticle immunoassay (r² = 0.9843), although there was a negative bias of - 17.82 (95 % confidence interval, -27.21 to - 8.44).

CONCLUSIONS

A highly sensitive, derivatization-free LC-MS/MS method was successfully developed in this study. This may be beneficial for estradiol measurements in patients with estradiol-related endocrine disorders.

Sample multiplexing for increasing throughput for quantification of estrogens in serum by LC-MS/MS

Estrogens are involved in many physiological processes in vivo. The accurate and rapid quantification of estrogens is required for the diagnosis and prognosis of estrogen-related diseases. To achieve high-volume assays, we developed and validated a sample-multiplexing liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of serum estrogens including estrone (E1), estradiol (E2), and estriol (E3). A total of 100 μL serum samples were extracted using ethyl acetate. After derivatization with either dansyl chloride or pyridine-3-sulfonyl chloride, derivatized samples were combined. Then we performed the second liquid-liquid extraction using hexane to purify the mixture. Finally, the reconstitution solutions were injected into LC-MS/MS. In addition, the proposed LC-MS/MS method was validated according to FDA and CLSI guidelines. Within a single run (7 min), this sample-multiplexing LC-MS/MS method could simultaneously analyze E1, E2, and E3 in 2 serum samples. Meanwhile, the method demonstrated satisfactory analytical characteristics including accuracy (87.7-110.3%), linearity (2-1000 pg/mL, R² > 0.99), precision (intra-assay CV, 1.7-8.7%; inter-assay CV, 1.9-9.4%), and negligible interference and carry-over effect as well as acceptable matrix effect. In conclusion, this sample-multiplexing LC-MS/MS method has achieved a doubled-throughput assay for simultaneous quantification of E1, E2, and E3 without compromising analytical characteristics.

Correlation of Menopausal Symptoms with Serum Estradiol: A Study in Urban Indian Postmenopausal Women

Background

Menopause is a hypoestrogenic state. Menopausal symptoms like hot flushes, depression, joint pains and urinary symptoms all correlate with falling estrogen levels.

Material and Methods

Four hundred postmenopausal women who underwent natural menopause were included in the study conducted from Nov 2018 to March 2020. Surgical menopause, premature menopause and those on hormone replacement were excluded. Serum estradiol was measured and assessment of severity of menopausal symptoms was done using MRS questionnaire. MRS score of 0-4, 5-8, 9-15 and more than 16 were taken as none/minimal, mild, moderate and severe postmenopausal symptoms, respectively. Correlation between serum estradiol and symptoms was analyzed statistically.

Results

Mean age of menopause in our study population was found to be 47.2 ± 3.96 years. Somatic symptoms were found maximum out of all 3 subscales in study population. Psychological subscale which included depression and mood changes was found to have the strongest correlation with serum estradiol level compared to other two subscales (somatic and genito-urinary).

Discussion

Psychological symptoms, somatic symptoms and genitor urinary symptoms at menopause show correlation with falling estrogen levels. We found maximum correlation of psychological symptoms with low serum estradiol level.

Conclusion

There is an inverse correlation of serum estradiol value with menopausal symptoms, with psychological symptoms (depression, anxiety, mood changes) showing highest correlation with low estrogen levels.

Liquid chromatography–tandem mass spectrometry for clinical diagnostics

Mass spectrometry is a powerful analytical tool used for the analysis of a wide range of substances and matrices; it is increasingly utilized for clinical applications in laboratory medicine. This Primer includes an overview of basic mass spectrometry concepts, focusing primarily on tandem mass spectrometry. We discuss experimental considerations and quality management, and provide an overview of some key applications in the clinic. Lastly, the Primer discusses significant challenges for implementation of mass spectrometry in clinical laboratories and provides an outlook of where there are emerging clinical applications for this technology.

Tandem mass spectrometry is increasingly utilized for clinical applications in laboratory medicine. In this Primer, Thomas et al. discuss experimental considerations and quality management for implementing clinical tandem mass spectrometry in the clinic with an overview of some key applications.

Pre-breeding androgen and glucocorticoid profiles in the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis)

Seasonally breeding species exhibit cyclical changes in circulating steroid hormone profiles that correspond with changes to their reproductive behavior and ecology. Such information is critical to the conservation of imperiled and data-deficient species, such as the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis). We determined changes in plasma testosterone (T), dihydrotestosterone (DHT), 11-ketotestosterone (11-KT), 11-ketoandrostenedione (11-KA), dehydroepiandrosterone (DHEA), cortisol, corticosterone, and progesterone (P₄) during a four-month period preceding breeding in adult male and female eastern hellbenders. This pre-breeding period is characterized by increased diel movement and aggression by both sexes, follicular development and yolk production in females, and sperm production, territoriality, and nest site establishment in males. In both males and females, we observed a progressive increase in circulating T and DHT during the pre-reproductive season, both peaking in August (17 days before breeding), but concentrations of both hormones were higher in males. Conversely, 11-KT was higher in females, but did not vary significantly by date. These results suggest that T and DHT are the predominant androgens in eastern hellbenders and are likely important regulators of reproductive processes in both males and females. The detection of significant quantities of DHT and 11-KT in females is particularly interesting, considering that unlike T, neither of these androgens can be converted to estrogens. Therefore, it seems possible that aggression or some aspect of reproduction in the female eastern hellbender may be directly mediated by androgen signaling. Baseline cortisol did not vary throughout the pre-breeding period but was higher in females than males, and also became highly variable in females leading up to breeding. Progesterone, 11-KA, DHEA, and corticosterone were rarely or never detected, and thus, do not appear to be important during the pre-reproductive season. This study provides a physiological framework for future studies of hellbender reproductive biology, which could ultimately be important for their conservation.

A Sensitive and Specific ESI-Positive LC-MS/MS Method for the Quantitation of Estrogens in Human Serum in Under Three Minutes

Amplifex Diene reagent was employed to derivatize estradiol (E2) to enhance the analyte signal at low picogram concentrations. This derivatization enabled measurement of E2 (and other estrogens) in ESI+ mode, earlier retention times for analytes than other methods, avoidance of MS harmful ammonium fluoride in mobile phases, and an LLOQ below 1 pg/mL. The sample preparation workflow involved liquid-liquid extraction followed by Amplifex Diene derivatization for 10 min at ambient temperature. Samples were chromatographed using a standard C18 column and analyzed using a SCIEX 6500+ mass spectrometer. The assay calibrators were prepared in-house, traceable to certified reference materials, and ranged from 1.29 to 624 pg/mL. A method comparison to samples from the CDC HoSt program yielded a correlation coefficient of 0.9858 and bias of -1.37%. The LLOQ using certified reference material was 0.66 pg/mL. The intra-run precision was <9.00% for low- and high-level samples, whereas the inter-run precision was 15.2 and 5.43% for low- and high-level samples, respectively. No interference from other clinically relevant steroids was found. Amplifex Diene derivatized E2 and estrone (E1) was found to be stable for over 6 months, both refrigerated and frozen.

Liquid chromatography-mass spectrometry applications for quantification of endogenous sex hormones

Liquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17-β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography-mass spectrometry. LC-MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high-resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC-MS/MS steroid hormone analysis captured in the literature over the last decade.

Analytical bias of automated immunoassays for six serum steroid hormones assessed by LC-MS/MS

Introduction

There is a growing amount of evidence showing the significant analytical bias of steroid hormone immunoassays, but large number of available immunoassays makes conduction of a single comprehensive study of this issue hardly feasible. Aim of this study was to assess the analytical bias of six heterogeneous immunoassays for serum aldosterone, cortisol, dehydroepiandrosterone sulphate (DHEAS), testosterone, 17-hydroxyprogesterone (OHP) and progesterone using the liquid chromatography coupled to the tandem mass spectrometry (LC-MS/MS).

Materials and methods

This method comparison study included 49 serum samples. Testosterone, DHEAS, progesterone and cortisol immunoassays were performed on the Abbott Architect i2000SR or Alinity i analysers (Abbott Diagnostics, Chicago, USA). DiaSorin’s Liaison (DiaSorin, Saluggia, Italy) and DIAsource’s ETI-Max 3000 analysers (DIAsource ImmunoAssays, Louvain-La-Neuve, Belgium) were chosen for aldosterone and OHP immunoassay testing, respectively. All immunoassays were evaluated against the LC-MS/MS assay relying on the commercial kit (Chromsystems, Gräfelfing, Germany) and LCMS-8050 analyser (Shimadzu, Kyoto, Japan). Analytical biases were calculated and method comparison was conducted using weighted Deming regression analysis.

Results

Depending on the analyte and specific immunoassay, mean relative biases ranged from -31 to + 137%. Except for the cortisol, immunoassays were positively biased. For none of the selected steroids slope and intercept 95% confidence intervals simultaneously contained 0 and 1, respectively.

Conclusions

Evaluated immunoassays failed to satisfy requirements for methods’ comparability and produced significant analytical biases in respect to the LC-MS/MS assay, especially at low concentrations.

Effectiveness of a Global Multidisciplinary Supportive and Educational Intervention in Thermal Resort on Anthropometric and Biological Parameters, and the Disease-Free Survival after Breast Cancer Treatment Completion (PACThe)

A growing knowledge highlights the strong benefit of regular physical activity in the management of breast cancer patients, but few studies have considered biological parameters in their outcomes. In the prospective randomised trial after breast cancer treatment completion “PACThe,” we determined the effects of physical activity and nutritional intervention on the biological and anthropometric status of patients after one year of follow-up, and clarified the link between biomarkers at allocation and disease-free survival. 113 patients from the population of the “PACThe” study (n = 251) were analysed for biological parameters. Patients were randomized after chemotherapy in two arms: the intervention “SPA” receiving a 2-week session of physical training, dietary education, and physiotherapy (n = 57), and the control “CTR” (n = 56). Diet questionnaire, anthropometric measures, and blood parameters were determined at allocation and one year later. Survival and recurrence were checked over 7 years. Data were considered as a function of BMI, i.e., ≤25 for normal, 25–30 for overweight, and >30 for obese patients. At allocation, the large standard deviation for nutrient-intake values reflected an unbalanced diet for some patients in the three groups. At one-year follow-up, we noticed an increase in glucose (p < 10⁻⁶), insulin (p < 10⁻⁷), and adiponectin (p < 0.022) plasma levels for both intervention arms, which were more accentuated for the >30 groups. Using the Cox model, we demonstrated that the highest testosterone plasma values were linked to an increase of the recurrence risk (HR [CI–95%] = 5.06 [1.66–15.41]; p=0.004). One-year after a global multidisciplinary supportive and educational intervention, we found few anthropometric and biological changes, mainly related to the patient's initial BMI. We highlighted the importance of plasma testosterone in the evaluation of patient's recurrence risk. Future studies would help better understand the mechanisms by which such multidisciplinary interventions could interact with breast cancer recurrence and define the most effective modalities.

Systemic estradiol levels with low-dose vaginal estrogens

OBJECTIVES

To critically evaluate published systemic estradiol levels during use of low-dose vaginal estrogens considering detection method and estrogen dose; describe challenges with accurately measuring estradiol; and determine the normal estradiol level range in postmenopausal women.

METHODS

PubMed was searched for studies reporting systemic estradiol levels with lower-dose vaginal estrogens (≤25 μg estradiol or 0.3 mg conjugated equine estrogens). Estradiol levels at baseline and during treatment, area under the curve, and maximum estradiol concentrations were summarized by dose within assay type. A proposed range of systemic estradiol in normal, untreated, postmenopausal women was estimated by conservatively pooling means and standard deviations from published studies.

RESULTS

Mean basal estradiol levels were 3.1 to 4.9 pg/mL using liquid or gas chromatography/mass spectroscopy (LC or GC/MS/MS) with a range of undetectable to 10.5 pg/mL using radioimmunoassay. Systemic estradiol levels with vaginal estrogens reflected their doses as measured with LC or GC/MS/MS in different studies: 7.1 to 9.1 pg/mL and 16.7 to 22.7 pg/mL with a 25-μg softgel capsule insert and a tablet insert, respectively; 4.6 to 7.4 pg/mL and 6.6 to 14.8 pg/mL with a 10-μg softgel capsule and a tablet insert, respectively; and 3.6 to 3.9 pg/mL with a 4-μg softgel capsule insert. A mean systemic estradiol concentration ranging from undetectable to 10.7 pg/mL is proposed as an estimate for basal estradiol levels in normal, untreated, postmenopausal women. Systemic estradiol absorption may be influenced by the placement of estradiol higher (as with an applicator) versus lower (as without an applicator) in the vagina, as estradiol transport to the uterus would be more likely further away than closer to the introitus.

CONCLUSION

Serum estradiol concentrations were generally lower when measured with more specific and sensitive assays. Estradiol absorption was dose-dependent, and may be influenced by dose, formulation, and positioning in the vagina. Very low systemic estradiol absorption with low/ultralow-dose vaginal estrogens may potentially decrease any adverse events that may be associated with higher doses of vaginal estrogens used for treating moderate to severe VVA due to less estradiol exposure.

Sex-specific Estrogen Levels and Reference Intervals from Infancy to Late Adulthood Determined by LC-MS/MS

CONTEXT

The lack of sensitive and robust analytical methods has hindered the reliable quantification of estrogen metabolites in subjects with low concentrations.

OBJECTIVE

To establish sex-specific reference ranges for estrone (E1) and estradiol (E2) throughout life and to evaluate sex-differences using the state-of-the-art liquid chromatography tandem mass spectrometry (LC-MS/MS) method for quantification of E1, E2, and estriol (E3).

DESIGN

LC-MS/MS method development and construction of estrogen reference ranges.

SETTINGS

Population-based cross-sectional cohorts from the greater Copenhagen and Aarhus areas.

PARTICIPANTS

Healthy participants aged 3 months to 61 years (n = 1838).

RESULTS

An isotope diluted LC-MS/MS method was developed and validated for measurements of serum E1, E2, and E3. Limits of detections (LODs) were 3 pmol/L (E1), 4 pmol/L (E2), and 12 pmol/L (E3), respectively. This sensitive method made it possible to differentiate between male and female concentration levels of E1 and E2 in children. In girls, E2 levels ranged from

CONCLUSION

Reference ranges of simultaneous quantification of E1 and E2 by this novel specific and highly sensitive LC-MS/MS method provide an invaluable tool in clinical practice and in future research studies.

Collapse

Key Words

• LC-MS/MS
• childhood
• estradiol
• estrone
• menopause
• menstrual cycle
• mini-puberty
• pubertal development
• reference range

Collapse

MESH Headings

• Adolescent
• Adult
• Child
• Child, Preschool
• Chromatography, Liquid/methods
• Chromatography, Liquid/statistics & numerical data
• Estradiol/blood
• Estrone/blood
• Female
• Healthy Volunteers
• Humans
• Infant
• Male
• Middle Aged
• Reference Values
• Sensitivity and Specificity
• Sex Factors
• Tandem Mass Spectrometry/methods
• Tandem Mass Spectrometry/statistics & numerical data
• Young Adult

Collapse

Grants

• Innovation Fund Denmark
• ReproUnion collaboration

Collapse

Affiliation(s)

Hanne Frederiksen Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark
Trine Holm Johannsen Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark
Stine Ehlern Andersen Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Jakob Albrethsen Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark
Selma Kløve Landersoe The Fertility Clinic, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Jørgen Holm Petersen Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark
Anders Nyboe Andersen The Fertility Clinic, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Esben Thyssen Vestergaard Paediatrics and Adolescent Medicine, Aarhus University Hospital, Aahus, Denmark
Mia Elbek Schorring Paediatrics and Adolescent Medicine, Aarhus University Hospital, Aahus, Denmark
Allan Linneberg Center for Clinical Research and Disease Prevention, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
Katharina M Main Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark
Anna-Maria Andersson Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark
Anders Juul Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), University of Copenhagen, Copenhagen, Denmark

Collapse

Quantitative analysis of underivatized 17 β-estradiol using a high-throughput LC-MS/MS assay - Application to support a pharmacokinetic study in ovariectomized guinea pigs

Difference in female sex hormone, β-estradiol (E₂), levels can contribute to sex differences in biological processes that underlie target tissue functions (QT interval), vulnerability to diseases (hepatitis or HIV), and response toward therapies. Accurate quantification of plasma E₂ level is thus an important aspect in both basic science research examining hormone-regulated physiological mechanisms and in clinical settings to support patient care associated with altered E₂ levels. Due to lack of a high-throughput high-sensitivity analytical method, we developed and validated a LC-MS/MS assay for accurate low-level quantification of E₂ and demonstrated its application to a guinea pig pharmacokinetic study in which guinea pigs were treated with 10 or 40 μg/kg E₂ subcutaneously and blood samples collected at 0 (pre-dose), 0.25, 0.5, 1, 2, 4, 8, 12 and 24 h post-dosing. E₂ was extracted using 90 μL ovariectomized guinea pig plasma by liquid-liquid extraction. The method was robust, sensitive with linear range from 3.9 to 1000 pg/mL, and the assay met acceptance criteria for validation parameters listed in the current FDA Guidance on Bioanalytical Method Validation. Compared to the 10 μg/kg dose, more than dose proportional increase in maximum E₂ plasma concentration (C_max) and AUC_0-∞ and correspondingly longer half-life were observed after 40 μg/kg dose. This assay is a significant improvement over existing E₂ quantification methods in bioanalytical field, with high precision and accuracy, low sample and injection volumes, no derivatization, and short assay run time of 3 min. This assay is amenable in high-throughput settings requiring low-level E₂ quantitation in basic science research and clinical settings.

Simultaneous quantification of estrogens and glucocorticoids in human adipose tissue by liquid-chromatography-tandem mass spectrometry

The presence of estrogens, androgens and glucocorticoids as well as their receptors and steroid converting enzymes in adipose tissue has been established. Their contribution to diseases such as obesity, diabetes and hormone-dependent cancers is an active area of research. Our objective was to develop a LC-MS/MS method to quantify bioactive estrogens and glucocorticoids simultaneously in human adipose tissue. Estrogens and glucocorticoids were extracted from adipose tissue samples using solid-phase extraction. Estrogens were derivatized using 1-(2,4-dinitro-5-fluorophenyl)-4-methylpiperazine (PPZ) and methyl iodide to generate a permanently charged molecule (MPPZ). Steroids were separated and quantified by LC-MS/MS. The limit of quantitation for the steroids was between 15 and 100 pg per sample. Accuracy and precision were acceptable (<20%). Using this method, estradiol, estrone, cortisone and cortisol were quantified in adipose tissue from women with and without breast cancer. This novel assay of estrogens and glucocorticoids by LC-MS/MS coupled with derivatization allowed simultaneous quantification of a panel of steroids in human adipose tissue across the endogenous range of concentrations encountered in health and disease.

Current strategies for quantification of estrogens in clinical research

Estrogens and their bioactive metabolites play key roles in regulating diverse processes in health and disease. In particular, estrogens and estrogenic metabolites have shown both protective and non-protective effects on disease pathobiology, implicating the importance of this steroid pathway in disease diagnostics and monitoring. All estrogens circulate in a wide range of concentrations, which in some patient cohorts can be extremely low. However, elevated levels of estradiol are reported in disease. For example, in pulmonary arterial hypertension (PAH) elevated levels have been reported in men and postmenopausal women. Conventional immunoassay techniques have come under scrutiny, with their selectivity, accuracy and precision coming into question. Analytical methodologies such as gas and liquid chromatography coupled to single and tandem mass spectrometric approaches (GC-MS, GC-MS/MS, LC-MS and LC-MS/MS) have been developed to quantify endogenous estrogens and in some cases their bioactive metabolites in biological fluids such as urine, serum, plasma and saliva. Liquid-liquid or solid-phase extraction approaches are favoured with derivatization remaining a necessity for detection in lower volumes of sample. The limits of quantitation of individual assays vary but are commonly in the range of 0.5-5 pg/mL for estrone and estradiol, with limits for their bioactive metabolites being higher. This review provides an overview of current approaches for measurement of unconjugated estrogens in biological matrices by MS, highlighting the advances in this field and the challenges remaining for routine use in the clinical and research environment.

Derivatization enhances analysis of estrogens and their bioactive metabolites in human plasma by liquid chromatography tandem mass spectrometry

Estrogens regulate many diverse biological processes in health and disease. They circulate at a wide range of concentrations in females generating several active metabolites (hydroxy and methoxyestrogens). The metabolites are assumed to be present in much lower levels and are thought to contribute to diseases such as pulmonary arterial hypertension (PAH). Estrogen metabolites are challenging to quantify in plasma and currently available immunoassays are non-specific. Here we have developed and validated a novel assay to simultaneously quantify parent estrogens and their metabolites by mass spectrometry (MS). Estrogens were extracted from human plasma using solid phase extraction and derivatized using 1-(5-fluoro-2, 4-dinitrophenyl)-4-methylpiperazine (PPZ) before quaternization by methylation ("MPPZ"). MPPZ derivatives were separated and quantified by liquid chromatography tandem MS (LC-MS/MS) in positive electrospray ionization mode, using a QTrap 6500 + coupled to a Shimadzu Nexera X2. Separation was achieved using an ACE Excel 2 C18-PFP column (2 μm, 2.1 mm × 150 mm). The limits of quantification (LOQ) were 0.43-2.17 pg on column with a linear range from 2 or 10 - 2000 pg mL-1. Intra and inter-day precision and accuracy were acceptable (<20% at LOQ and <15% above). These derivatives demonstrated minimal degradation upon short-term storage at 15 °C (<20%) and longer term at -20 °C (<20%). Using this approach, estrone (E1) and estradiol (E2) were detected in plasma (0.5 mL) from healthy women and those with PAH but downstream metabolites 16-hydroxy-E1, 16-hydroxy-E2, 2-methoxy-E1 and 4-methoxy-E1 were only detected in plasma from diseased patients. These findings will next be tested robustly in large patient cohorts. This novel LC-MS/MS analysis of estrogens and their bioactive metabolites, using MPPZ derivatization, opens doors for the simultaneous analysis of a panel of estrogens in human plasma, across the endogenous range of concentrations encountered in health and disease.

Comparison of isotope pattern deconvolution and calibration curve quantification methods for the determination of estrone and 17β-estradiol in human serum

A Liquid Chromatography coupled to tandem mass spectrometry (LC-MS/MS) based method have been developed for the determination of the main estrogen compounds -estrone (E1) and 17β-estradiol (E2)- in human serum. Two isotope dilution mass spectrometry (IDMS) quantification procedures have been used: a classical calibration curve-based method were compared to a recently developed isotope pattern deconvolution (IPD) method. IPD is based on isotopic abundance measurements and multiple linear regression. Validation was performed in terms of intra-assay repeatability (n = 5), inter-assay reproducibility (n = 9) and accuracy using spiked steroid-free serum at 5 concentration levels and 3 certified reference materials. Both methodologies meet EMEA requirements yielding recoveries between 79-106% and coefficient of variations of 1.7-8.3% along all experiments. Limits of quantification as low as 5 ng/L were achieved. 40 real samples were analysed for comparison purposes showing a great correlation between calibration and IPD concentration values. Real samples were also quantified by routine immunoassay analysis, which showed a significant proportional bias of 2.55 for E1 and good correlation for E2. While methods were considered suitable for routine or countercheck analysis within the context of hospital's needs, IPD has demonstrated to be faster and cost saving.

Sex steroids in serum and prostatic tissue of human cancerous prostate (STERKPROSER trial)

BACKGROUND

Currently, there is no consensus regarding the expected concentration levels of intra-prostatic sex steroids in patients with Prostate Cancer (PCa). Our objective was to assess the concentration levels of sex steroids in prostatic tissue and serum, in two cohorts of patients with localized PCa or benign prostatic hyperplasia (BPH).

METHODS

Between September 2014 and January 2017, men selected for radical cystectomy (for bladder cancer) or open prostatectomy (for BPH), and men selected for radical prostatectomy for localized PCa were included. Blood samples were collected at baseline before surgery, and steroid concentrations were assessed following the recommendations of the Endocrine Society. Intra-prostatic samples were collected from fresh surgical samples, and assessed by gas chromatography and mass spectrometry (GC/MS). Permanova analysis was performed. Analyses were adjusted for age, prostate weight, and prostate-specific antigen (PSA) level.

RESULTS

A total of 73 patients (41 patients with PCa and 32 patients with BPH) were included in this study. Patients with PCa were younger, and had smaller prostate volumes with higher levels of PSA. The levels of Total Testosterone (TT), Di-Hydro-Testosterone (DHT), and Estradiol (E2) in the serum were not significantly different between PCa and BPH. In PCa tissue, TT concentrations were significantly lower (0.11 ng/g vs 0.47 ng/g, P = 0.0002), however its derivative E2 had significantly higher concentrations (31.0 ng/g vs 22.3 ng/g, P = 0.01). DHT tissue concentrations were not significantly different between the two groups (5.55 ng/g vs 5.42 ng/g, P = 0.70). Intra-prostatic TT concentrations were significantly lower in the peripheral zone than in the central zone for the CaP group (0.07 ng/g vs 0.15 ng/g, P = 0.004).

CONCLUSIONS

Patients with PCa had lower intra-prostatic TT and higher E2 concentrations levels compared to the patients with BPH. PCa seem to consume more TT and produce more E2, especially in the peripheral zone.

Advances in mass spectrometry-based glycomics

The diversification of the chemical properties and biological functions of proteins is attained through posttranslational modifications, such as glycosylation. Glycans, which are covalently attached to proteins, play a vital role in cell activities. The microheterogeneity and complexity of glycan structures associated with proteins make comprehensive glycomic analysis challenging. However, recent advancements in mass spectrometry (MS), separation techniques, and sample preparation methods have primarily facilitated structural elucidation and quantitation of glycans. This review focuses on describing recent advances in MS-based techniques used for glycomic analysis (2012-2018), including ionization, tandem MS, and separation techniques coupled with MS. Progress in glycomics workflow involving glycan release, purification, derivatization, and separation will also be highlighted here. Additionally, the recent development of quantitative glycomics through comparative and multiplex approaches will also be described.

Measuring estrogens in women, men, and children: Recent advances 2012-2017

The measurement of estrogens is important for diagnosing and monitoring the health of women, men, and children. For example, for postmenopausal women or women undergoing treatment for breast cancer with aromatase inhibitors, the measurement of extremely low concentrations of estrogens in serum, especially estradiol, is problematic but essential for proper medical care. Achieving superb analytical sensitivity and specificity has been and continues to be a challenge for the clinical laboratory, but is a challenge that is being taken seriously. Focusing on publications from 2012 to 2017, this review will provide an overview of recent research in the development of methods to accurately and precisely measure estrogens, including a variety of estrogen metabolites. Additionally, the latest in clinical research involving estrogen measurement in women, men, and children will be presented to provide an update on the association of estrogens with diseases or conditions such as breast cancer, precocious puberty, infertility, and pregnancy. This research update will provide context as to why estrogen measurement is important and why laboratories are working hard to support the recommendations made by the Endocrine Society regarding estrogen measurement.

Biochemistry of the menopause

The life of a human female is characterized from teenage years by monthly menstruation which ceases (the menopause) typically between the age of 40 and 60 years. The potential for reproduction declines and ceases as the ovaries become depleted of follicles. A transition period in mid-life, for 2 to 10 years, when menstruation is less regular is called the perimenopause. The menopause is associated with a significant decline in plasma concentrations of sex hormones, an increase in the concentrations of the gonadotrophins and changes in other hormones such as the inhibins. These changes are superimposed with effects of aging, social and metabolic factors, daily activity and well-being. Although the menopause is entirely natural, in some cases ovarian failure can occur earlier than usual; this is pathological and warrants careful biochemical investigations to distinguish it from conditions causing infertility. Elderly females are affected by a range of clinical disorders including endocrine, cardiovascular, skeletal, urogenital tract and immunological systems, body mass, vasomotor tone, mood and sleep pattern. Reference intervals for many diagnostic biochemical tests for the menopause need to be used when interpreting results in clinical investigations for patient management. The standardization and harmonization of assays are being addressed. Many women now choose to develop their career before bearing children, and the health service has had to change services around this. This review does not cover screening for and tests during pregnancy. The review is timely since the population is aging and there will be more demand on healthcare services.

Sexual steroids in serum and prostatic tissue of human non-cancerous prostate (STERPROSER trial)

BACKGROUND

The specific involvement of the sex steroids in the growth of the prostatic tissue remains unclear. Sex steroid concentrations in plasma and in fresh surgical samples of benign central prostate were correlated to prostate volume.

METHODS

Monocentric prospective study performed between September 2014 and January 2017. Age, obesity parameters, and both serum and intraprostatic concentrations of sex steroids were collected complying with the latest Endocrine Society guidelines and the steroids assessed by GC/MS. Statistical calculations were adjusted for age and body mass index (BMI).

RESULTS

Thirty-two patients, equally divided between normal- and high-volume prostate groups, were included in the analysis. High-volume prostate patients were older, heavier and had higher BMI. Comparison adjusted for age and BMI showed higher DHT concentrations in high-volume prostate. Both normal- and high-volume prostate tissues concentrate sex steroids in a similar way. Comparison of enzymatic activity surrogate marker ratios within tissue highlighted similar TT/E1 and TT/E2 ratios, and higher DHT/E1 ratio and lower DHT/PSA ratio in the high-volume prostates.

CONCLUSIONS

STERPROSER trial provides evidence for higher DHT concentration in highvolume prostates, that could reflect either higher 5-alpha reductase expression or lower expression of downstream metabolizing enzymes such as 3a-hydoxysteroid dehydrogenase.

Ultra-performance liquid chromatography-tandem mass spectrometry assay for determination of plasma nomegestrol acetate and estradiol in healthy postmenopausal women

A highly sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry method is described for the simultaneous determination of nomegestrol acetate (NOMAC), a highly selective progestogen, and estradiol (E2), a natural estrogen in human plasma. NOMAC was obtained from plasma by solid-phase extraction, while E2 was first separated by liquid-liquid extraction with methyl tert-butyl ether followed by derivatization with dansyl chloride. Deuterated internal standards, NOMAC-d5 and E2-d4 were used for better control of extraction conditions and ionization efficiency. The assay recovery of the analytes was within 90-99%. The analytes were separated on UPLC BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column using a mobile phase comprising of acetonitrile and 3.0 mm ammonium trifluoroacetate in water (80:20, v/v) with a resolution factor (R_s ) of 3.21. The calibration curves were linear from 0.01 to 10.0 ng/mL for NOMAC and from 1.00 to 1000 pg/mL for E2, respectively. The intra- and inter-batch precision was ≤5.8% and the accuracy of quality control samples ranged from 96.7 to 103.4% for both analytes. The practical applicability of the method is demonstrated by analyzing samples from 18 healthy postmenopausal women after oral administration of 2.5 mg nomegestrol acetate and 1.5 mg estradiol film-coated tablets under fasting.

Development of LC-MS/MS Confirmatory Method for the Determination of Testosterone in Bovine Serum

Introduction

In the European Union the use of steroid growth promoters is prohibited under Council Directive 96/22/EC. For effective control of illegal use of natural steroids, highly sensitive analytical methods are required, because sex hormones can be present in very low concentrations in biological samples. The aim of the study was to develop a confirmatory method for the detection of testosterone in bovine serum at ppt level.

Material and Methods

17β-testosterone and internal standards of 17%-testosterone-d2 were extracted from serum samples with a mixture of tert-butyl methyl ether/petroleum ether and were directly analysed by an LC/MS/MS on QTRAP 5500 instrument with a TurboIon-Spray source operating in a positive ionisation mode. Chromatographic separation was achieved on the analytical column Inertsil® ODS-3 with an isocratic elution using mobile phase consisting of acetonitrile, methanol, and water. Method validation has been carried out in accordance with the Commission Decision 2002/657/EC.

Results

The method was characterised by good recovery (82%) and precision (R.S.D 17 %). Decision limit (CCα) and detection capability (CCβ) was 0.05 μg L⁻¹ and 0.09 μg L⁻¹ respectively. The method met the criteria set out in Commission Decision 2002/657/EC for the purpose of confirmation in terms of retention time and ion ratio in the whole range of its application.

Conclusions

The developed method is specific and sensitive, suitable for measuring the natural level of testosterone in blood of cattle and for use in routine control programme for the detection of this hormone in bovine serum.

Simultaneous quantification of estrogens, their precursors and conjugated metabolites in human breast cancer cells by LC-HRMS without derivatization

Liquid chromatography-mass spectrometry (LC-MS) is the state of the art technique for quantification of steroid hormones. Currently used methods are typically limited by the need of pre-column derivatization to increase ionization efficiency; however, this causes hydrolysis of conjugated metabolites. Our newly established LC-HRMS method is able to simultaneously quantify conjugated and unconjugated steroids without prior derivatization using deuterated internal standards and solid-phase extraction. This assay was validated according to ICH Q2(R1) guidelines for the analysis of the 10 main steroids of the estrogenic pathway, namely 4-androstene-3,17-dione, dehydroepiandrosterone (DHEA), DHEA-3-sulfate, estrone, 17β-estradiol, estriol (16α-OH-17β-estradiol), estrone-3-sulfate, 17β-estradiol-3-(β-d-glucuronide), 17β-estradiol-3-sulfate and testosterone. Assay performance characteristics were excellent with results for accuracy (98.8-101.2%), precision (mean: 2.05%, all ≤2.80%), stability over five freeze-thaw-cycles (95.7-100.4%) and SPE accuracy (96.9-102.0%), as well as suitable lower and upper limits of quantification for cell culture experiments (LLOQ 0.005-2ng/ml, ULOQ 3-2000ng/ml). Furthermore, we demonstrated the functionality of our method for the monitoring of steroid levels in the human breast cancer cell line MCF-7. This sensitive assay allows for the first time detailed investigations on estrogen metabolomics in breast cancer cells and may also apply to other estrogen-dependent tumor entities.

Sensitive simultaneous quantitation of testosterone and estradiol in serum by LC-MS/MS without derivatization and comparison with the CDC HoSt program

BACKGROUND

Very sensitive measurements of serum estrogens and testosterone are important in adult and pediatric endocrinology and immunoassays are known to lack the required performance at very low levels. Our aim was to develop a sensitive HPLC-MS/MS assay for both estradiol (E₂) and testosterone (Te) in serum without the need for chemical derivatization and using commercially available calibrators.

METHODS

Serum samples were prepared by the addition of internal standards followed by extraction using hexane:ethyl acetate. Chromatographic separation was achieved using a C₁₈ column and mass spectrometry was performed in both positive and negative ion modes.

RESULTS

The lower limits of quantitation (LLOQs) of E₂ and Te were 5pg/mL and 1ng/dL, respectively. The analytical measurement range (AMR) for E₂ was 5-600pg/mL and 1-1,170ng/dL for Te. Assay accuracy was determined both by comparison with a LC-MS/MS method performed at a national laboratory and the CDC HoSt program. Comparison with samples analyzed by both methods showed excellent correlation. Within-day (N=10) and between-day (N=20) CVs at concentrations spanning the AMR were less than 7% for both analytes.

CONCLUSION

We have developed an accurate and highly sensitive assay to measure E₂ and Te levels in serum by HPLC-MS/MS without chemical derivatization and using commercially available calibrators.

A proposal to improve calibration and outlier detection in high-throughput mass spectrometry

Instrument calibration, required for any accurate quantitative calculation, is a trivial process when performed correctly, but is also full of easily overlooked stumbling blocks. To minimize the risk of error associated with improper calibrations, national and international guidance dictates a minimum number of calibrators and the threshold at which a measurement becomes an outlier. Evidence from industry practice, which conflicts with regulatory guidance, suggests that most groups are focused on remapping their detector with each run. We present a post facto explanation for the calibrator minimum and provide recommendations for curve building, which include improved outlier detection for high-volume mass spectrometry laboratories.

Simultaneous determination of levonorgestrel and two endogenous sex hormones in human plasma based on LC-MS/MS

BACKGROUND

Levonorgestrel (LNG) is a commonly used emergency contraceptive which can effect sex hormone levels in female blood. The objective of this study was to develop and validate a specific and sensitive LC-MS/MS method for monitoring endogenous sex hormone levels (17β-estradiol and progesterone) in female plasma after administration of LNG. Results & methodology: The method was developed, optimized and validated according to the EMA guideline. Assay validation met all the criteria, including good linearity in the range of 0.1-20 ng/ml for 17β-estradiol, as well as 0.2-30 ng/ml for LNG and progesterone.

CONCLUSION

The method has been preliminarily applied to explore the variation trend of sex hormone levels in healthy Chinese female volunteers' plasma after oral administration of 1.5 mg LNG tablet. With LNG absorption into plasma, progesterone and estradiol levels descended rapidly, and maintained at low levels in the onset time.

Role of mass spectrometry in steroid assays

In addition to protein hormones, steroids measurement constitutes the basis of modern endocrinology. Immunoassays have shown their limits in this field. In contrast, mass spectrometry shows an excellent sensitivity and specificity that make it the method of choice for steroids assays. The recent introduction of UHPLC-MS is a major advance which reinforces this position. In fact, mass spectrometry provides a lot of advantages such as determination of certain steroids in saliva, diagnosis of enzyme deficiencies, or measurement of molecules previously inaccessible like aldosterone. However, standardization is still needed to ensure good comparability of results between laboratories. In the future, mass spectrometry should not replace the immunoassays but rather complement it.

Derivatization of estrogens enhances specificity and sensitivity of analysis of human plasma and serum by liquid chromatography tandem mass spectrometry

Estrogens circulate at concentrations less than 20 pg/mL in men and postmenopausal women, presenting analytical challenges. Quantitation by immunoassay is unreliable at these low concentrations. Liquid chromatography tandem mass spectrometry (LC–MS/MS) offers greater specificity and sometimes greater sensitivity, but ionization of estrogens is inefficient. Introduction of charged moieties may enhance ionization, but many such derivatives of estrogens generate non-specific product ions originating from the “reagent” group. Therefore an approach generating derivatives with product ions specific to individual estrogens was sought.

Estrogens were extracted from human plasma and serum using solid phase extraction and derivatized using 2-fluoro-1-methylpyridinium-p-toluenesulfonate (FMP-TS). Electrospray in positive mode with multiple reaction monitoring using a QTrap 5500 mass spectrometer was used to quantify “FMP” derivatives of estrogens, following LC separation.

Transitions for the FMP derivatives of estrone (E1) and estradiol (E2) were compound specific (m/z 362→238 and m/z 364→128, respectively). The limits of detection and quantitation were 0.2 pg on-column and the method was linear from 1–400 pg/sample. Measures of intra- and inter-assay variability, precision and accuracy were acceptable (<20%). The derivatives were stable over 24 h at 10 °C (7–9% degradation). Using this approach, E1 and E2, respectively were detected in human plasma and serum: pre-menopausal female serum (0.5 mL) 135–473, 193–722 pmol/L; male plasma (1 mL) 25–111, 60–180 pmol/L and post-menopausal female plasma (2 mL), 22–78, 29–50 pmol/L.

Thus FMP derivatization, in conjunction with LC–MS/MS, is suitable for quantitative analysis of estrogens in low abundance in plasma and serum, offering advantages in specificity over immunoassay and existing MS techniques.

•

Quantitative analysis of low amounts of estrone and estradiol in plasma and serum.

•

Quantitation across physiological range in men and pre- and post-menopausal women.

•

Methylpyridinium ether derivatives improve analytical specificity and sensitivity.

The Associations Between Body Mass Index, Smoking, and Alcohol Intake with Ovarian Volume in Midlife Women

BACKGROUND

Despite the fact that ovarian volume is a marker of reproductive aging, there is little understanding of factors related to ovarian volume among aging women. The objective of this analysis was to examine the associations between body mass index (BMI), cigarette smoking, and alcohol intake with ovarian volume among midlife women.

MATERIALS AND METHODS

Data were analyzed from 771 women (45-54 years of age at baseline) enrolled in the Midlife Women's Health Study, a cohort study that was initiated in 2006. At annual clinic visits, height and weight were measured, a transvaginal ultrasound was performed to measure ovarian volume, blood was drawn to measure hormone concentrations, and a comprehensive questionnaire was administered. Generalized linear models and repeated measures mixed models were conducted to examine the associations between BMI, cigarette smoking, and alcohol intake with ovarian volume, adjusting for age and race.

RESULTS

Age was significantly and negatively associated with ovarian volume. However, BMI, smoking, and alcohol use were not associated with ovarian volume either when stratified by menopausal status or when adjusting for age and race. Estradiol, but not progesterone or testosterone, was significantly and positively associated with ovarian volume overall and among both white and black participants (p < 0.05).

CONCLUSIONS

This study provides insight into the associations between BMI, smoking, and alcohol use with ovarian volume among midlife women. The findings are somewhat consistent with the published literature and, thus, indicate that these factors may not be clinically important in terms of ovarian volume during the menopausal transition.

A chromatography/tandem mass spectrometry method for the simultaneous profiling of ten endogenous steroids, including progesterone, adrenal precursors, androgens and estrogens, using low serum volume

Measurement of a large set of sex steroids in clinical epidemiology and laboratory research with reliable methods providing low quantification limits and using a limited volume of blood sample represents a significant challenge. We report a new validated gas chromatography selected reaction monitoring - tandem mass spectrometry assay (GC-MS/MS) for the simultaneous quantification of ten endogenous steroids including progesterone (PROG), dehydroepiandrosterone (DHEA), androstenediol (5-diol), androstenedione (4-dione), testosterone (T), dihydrotestosterone (DHT), androsterone (ADT), 5alpha-androstan-3beta-17beta-diol (3β-diol), estrone (E1) and estradiol (E2). After addition of stable isotope internal standards, the approach involved the combination of liquid-liquid extraction, derivatization and solid-phase extraction for injection into the GC system and multiple reaction monitoring (MRM). The method presents high reproducibility for all analytical parameters in 250 μl serum samples. The lower limit of quantification (LLOQ) were of 100 pg/ml for DHEA, 50 pg/ml for PROG, 5-diol, 4-dione and ADT, 30 pg/ml for T, 10 pg/ml for 3β-diol and DHT, 5 pg/ml for E1, and 1 pg/ml for E2. The applicability of the validated method to determine the concentrations of these 10 steroids was successfully tested on serum from men (n=15), premenopausal (n=10) and postmenopausal women (n=20), and is currently used for larger cancer-related epidemiology studies. One of the most considerable advantages over existing methods is the simultaneous determination of ten steroids in a limited volume of serum that will help conserve important clinical samples from existing biobanks.