High-sensitivity tandem mass spectrometry assay for serum estrone and estradiol

Hyperestrogenism Affects Adult Height Outcome in Growth Hormone Treated Boys With Silver-Russell Syndrome

Background: Intrauterine growth retardation and short stature are common features in Silver-Russell syndrome (SRS). Despite recombinant growth hormone (rGH) treatment, poor pubertal height gain, affecting adult height (AH), is common. This study investigated whether growth patterns and estrogen concentrations are associated with AH outcome in rGH treated SRS males. Methods: In this retrospective longitudinal single-center study, 11 males with SRS were classified as non-responders (NR = 6) or responders (R = 5), depending on AH adjusted for midparental height. Epigenetic analysis and longitudinal growth measures, including bone age, rGH related parameters, pubertal development, gonadotropins and estrogen concentrations, were analyzed until AH. Results: Pubarche before 9 years was only observed in one NR. At 10 years of age, there was no difference in gonadotropins between NR and R. However, estradiol (E2) concentrations at 10 years of age showed a strong association to AH adjusted for MPH (r = -0.78, p < 0.001). Serum E2 (pmol/L) was significantly higher in NR at ages 10 years [median (range) 2 (<2-5) vs. <2 (<2)], 12 years [23 (10-57) vs. 2 (<2-2)] and 14 years [77 (54-87) vs. 24 (<2-38)] but not at 16 years. Birth weight standard deviation score (SDS) was lower in NR [-4.1 (-4.7 to -2.1) vs. -2.7 (-3.3 to -1.7)]. Weight gain (SDS) until pubertal onset was greater in NR [2.4 (1.4-3.5) vs. 0.8 (-0.4 to 1.7)] and pubertal height gain (SDS) was lower in NR [-1.0 (-2.7-0.4) vs. 0.1 (-0.1 to 1.1)]. At AH, a number of NR and R had high E2 concentrations and small testes. Conclusion: Increased E2 concentrations at age 10, 12, and 14 years were associated to less pubertal height gain, thus affecting AH. Due to the small number of patients, the results need to be confirmed in larger cohorts. The finding of impaired testicular development stresses the need of hormonal evaluation as a complement to clinical and radiological assessment when predicting AH in males with SRS.

Steroid hormone profiling in human breast adipose tissue using semi-automated purification and highly sensitive determination of estrogens by GC-APCI-MS/MS

Body mass index is a known breast cancer risk factor due to, among other mechanisms, adipose-derived hormones. We developed a method for steroid hormone profiling in adipose tissue to evaluate healthy tissue around the tumor and define new biomarkers for cancer development. A semi-automated sample preparation method based on gel permeation chromatography and subsequent derivatization with trimethylsilyl (TMS) is presented. Progestagens and androgens were determined by GC-EI-MS/MS (LOQ 0.5 to 10 ng/g lipids). For estrogen measurement, a highly sensitive GC-APCI-MS/MS method was developed to reach the required lower limits of detection (0.05 to 0.1 ng/g lipids in matrix, 100-200 fg on column for pure standards). The combination of the two methods allows the screening of 27 androgens and progestagens and 4 estrogens from a single sample. Good accuracies and repeatabilities were achieved for each compound class at their respective limit of detection. The method was applied to determine steroid hormone profiles in adipose tissue of 51 patients, collected both at proximity and distant to the tumor. Out of the 31 tested steroid hormones, 14 compounds were detected in human samples. Pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone (DHEA), and androstendione accounted together for 80% of the observed steroid hormone profiles, whereas the estrogens accounted for only 1%. These profiles did not differ based on sampling location, except for ß-estradiol; steroid hormone conversions from androgens to estrogens that potentially take place in adipose or tumoral tissue might not be detectable due a factor 100 difference in concentration of for example DHEA and ß-estradiol. Graphical Abstract Schematic overview of the determination of steroid hormones and metabolites in adipose tissue in proximity and distal to the tumor.

Simultaneous determination of three estrogens in human saliva without derivatization or liquid-liquid extraction for routine testing via miniaturized solid phase extraction with LC-MS/MS detection

Accurate quantitation of estrogens (i.e, estrone (E1), estradiol (E2) and estriol (E3)) is valuable for clinical assessment of human health and disease. Alterations in estrogen levels have been implicated in numerous pathological conditions. However, inadequacies in sensitivity and specificity, cumbersome sample preparation and invasive specimen collection hamper the usability of available methods for clinical applications. Herein, a simple, rapid, highly sensitive and specific LC-MS/MS method was developed and validated for the simultaneous determination of three estrogens in human saliva providing a non-invasive alternative to conventional blood samples. For the first time, a 96-well hydrophilic-lipophilic-balanced (HLB) microplate was employed for clean-up and enrichment of estrogens in a single extraction without the requirements of derivatization, evaporation, liquid-liquid extraction and online extraction. A rapid LC chromatographic separation with a turnaround time of 5.0min was achieved on a BEH C18 XP column. The use of 0.1mM ammonium fluoride (NH₄F) as LC additive, and integration of summated and scheduled multiple reaction monitoring (MRM) transitions substantially improved the sensitivity to 1pg/mL, allowing the accurate quantitation of trace levels of three estrogens in one run. The assay was fully validated with good performance for extraction efficiency (67.0-85.6%), matrix effect (89.6-100.2%), linearity (from 1.0pg/mL up to 1000pg/mL), accuracy (98.9-112.4%) and precision (≤7.4%). Additionally, the assay was unaffected by 34 structurally-similar, potentially interfering substances tested at high clinical concentrations. The applicability of the assay was demonstrated by assessing the reference intervals of authentic saliva samples from healthy adult males, pre- and post-menopausal females. The easy sample preparation, fast LC and multi-analyte MS/MS detection utilizing noninvasive saliva as a specimen delivers a simple, practical, sensitive and accurate tool suitable for the high throughput measurement of E1, E2 and E3 in clinical laboratories.

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.

Role of Mass Spectrometry in Clinical Endocrinology

The advent of mass spectrometry into the clinical laboratory has led to an improvement in clinical management of several endocrine diseases. Liquid chromatography tandem mass spectrometry found some of its first clinical applications in the diagnosis of inborn errors of metabolism, in quantitative steroid analysis, and in drug analysis laboratories. Mass spectrometry assays offer analytical sensitivity and specificity that is superior to immunoassays for many analytes. This article highlights several areas of clinical endocrinology that have witnessed the use of liquid chromatography tandem mass spectrometry to improve clinical outcomes.

Simultaneous measurement of total estradiol and testosterone in human serum by isotope dilution liquid chromatography tandem mass spectrometry

Reliable measurement of total testosterone and estradiol is critical for their use as biomarkers of hormone-related disorders in patient care and translational research. We developed and validated a mass spectrometry method to simultaneously quantify these analytes in human serum without chemical derivatization. Serum is equilibrated with isotopic internal standards and treated with acidic buffer to release hormones from their binding proteins. Lipids are isolated and polar impurities are removed by two serial liquid-liquid extraction steps. Total testosterone and estradiol are measured using liquid chromatography tandem mass spectrometry (LC-MS/MS) in combination of positive and negative electrospray ionization modes. The method shows broad analytical measurement range for both testosterone 0.03-48.5 nM (0.75-1400 ng/dL) and estradiol 11.0-5138 pM (2.99-1400 pg/mL) and excellent agreement with certified reference materials (mean bias less than 2.1% to SRM 971, BCR 576, 577, and 578) and a high order reference method (mean bias 1.25% for testosterone and -0.84% for estradiol). The high accuracy of the method was monitored and certified by CDC Hormone Standardization (HoSt) Program for 2 years with mean bias -0.7% (95% CI -1.6% to 0.2%) for testosterone and 0.1% (95% CI -2.2% to 2.3%) for estradiol. The method precision over a 2-year period for quality control pools at low, medium, and high concentrations was 2.7-2.9% for testosterone and 3.3-5.3% for estradiol. With the consistently excellent accuracy and precision, this method is readily applicable for high-throughput clinical and epidemiological studies.

Circulating Estrogen Levels and Self-Reported Health and Mobility Limitation in Community-Dwelling Men of the Framingham Heart Study

Background

Self-rated health is a commonly used global indicator of health status. Few studies have examined the association of self-rated health and mobility with estrone and estradiol in men. Accordingly, we determined the cross-sectional, incident, and mediating relations between circulating estrone and estradiol levels with self-rated health, mobility limitation, and physical performance in community-dwelling men.

Methods

The cross-sectional sample included 1,148 men, who attended Framingham Offspring Study Examinations 7 and 8. Estrone and estradiol levels were measured using liquid chromatography tandem mass spectrometry at Examination 7. Self-reported mobility limitation and self-rated health were assessed at Examinations 7 and 8. Additionally, short physical performance battery, usual walking speed, and grip strength were assessed at Examination 7.

Results

In incident analysis, estradiol levels at Examination 7 were associated with increased odds of fair or poor self-rated health at Examination 8, after adjusting for age, body mass index, comorbidities, and testosterone levels; in an individual with 50% greater estradiol than other, the odds of reporting "fair or poor" self-rated health increased by 1.78 (95% confidence interval: 1.25-2.55; p = .001). Neither estrone nor estradiol levels were associated with any physical performance measure at baseline.

Conclusions

Higher circulating levels of estradiol are associated with increased risk of incident fair/poor self-rated health in community-dwelling men. The mechanisms by which circulating levels of estradiol are related to self-rated health in men need further investigation.

Challenges of measuring accurate estradiol levels in aromatase inhibitor-treated postmenopausal breast cancer patients on vaginal estrogen therapy

Breast cancer patients who are taking adjuvant Aromatase Inhibitor (AI) therapy typically have extremely low estradiol levels, which are undetectable by routine clinical laboratories. Thus, it becomes difficult to assess the safety of interventions such as low‐dose vaginal estrogen, which may increase estradiol levels. In this study, we aimed to assess the utility of enzyme‐linked immunosorbent assay (ELISA) to measure low estradiol concentrations in breast cancer survivors on AI therapy treated with either vaginal estrogen or lubricant for atrophic vaginitis as a part of clinical trial. The samples were tested using two independent ELISA kits. Some of the samples were also evaluated using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) for comparison. We found that while the results by ELISA were reproducible, they were not accurate when compared to LC‐MS/MS. It is possible that medications or supplements may cross‐react with the ELISA reagents and confound the assessment; however, those were often not the reason for the discrepancy. Our results highlight the need for developing novel, reliable, and clinically accessible assays to measure ultra‐low estradiol levels to improve care of breast cancer survivors. At this stage, based on our findings, we recommend using MS‐based assays for estradiol quantitation for breast cancer survivors, whenever necessary.

Analysis of 17β-estradiol, estriol and estrone in American eel (Anguilla rostrata) tissue samples using liquid chromatography coupled to electrospray differential ion mobility tandem mass spectrometry

RATIONALE

17β-Estradiol (E2), estrone (E1) and estriol (E3) are steroid hormones responsible for the regulation of the female reproductive system. Estradiol is planned to be used to feminize eels in aquaculture in order to improve their size and marketability. The residual levels of these hormones in fish tissue must be monitored to meet the requirements of food regulatory agencies. Few studies have studied these hormones in complex biological matrices such as fish tissue.

METHODS

We developed a method to analyze E1, E2 and E3 in fish tissue using liquid chromatography in combination with differential ion mobility spectrometry (DMS) and tandem mass spectrometry (MS/MS). The mass spectrometer was operated in negative polarity selected reaction monitoring (SRM) mode. To test the performance of this method, residual levels of E1, E2 and E3 were measured in the muscle tissue of juvenile eels subjected to feminization treatment with E2.

RESULTS

We report that following 17β-estradiol treatment, E2 is rapidly metabolized from the eel tissue, with a 50% depletion rate per day. Five days post-treatment, E2 returned to the level found in non-treated controls, similar to levels found in wild mature female eels.

CONCLUSIONS

The method presented herein allows the quantitative analysis of E1, E2 and E3 in fish tissue samples. Under the experimental conditions, E2 in fish tissue samples returned to physiological levels post hormonal treatment. Copyright © 2017 John Wiley & Sons, Ltd.

Advances in Clinical Mass Spectrometry

Although mass spectrometry has been used clinically for decades, the advent of immunoassay technology moved the clinical laboratory to more labor saving automated platforms requiring little if any sample preparation. It became clear, however, that immunoassays lacked sufficient sensitivity and specificity necessary for measurement of certain analytes or for measurement of analytes in specific patient populations. This limitation prompted clinical laboratories to revisit mass spectrometry which could additionally be used to develop assays for which there was no commercial source. In this chapter, the clinical applications of mass spectrometry in therapeutic drug monitoring, toxicology, and steroid hormone analysis will be reviewed. Technologic advances and new clinical applications will also be discussed.

Altered adrenal and gonadal steroids biosynthesis in patients with burn injury

Introduction

Burn injury inevitably leads to changes in the endogenous production of cytokines, as well as adrenal and gonadal steroids. Previous studies have reported gender-related differences in outcome following burn injury, which suggests that gonadal steroids may play a role. The aim of this study was to assess alterations in concentration of endogenous steroids in patients with burn injury.

Methods

For this single-center, prospective descriptive study, high-sensitivity liquid chromatography tandem mass spectrometry (LC-MS/MS)-based steroid quantification was used to determine longitudinal profiles of the concentrations of endogenous steroids in plasma from sixteen adult male patients with burn injury (14.5-72% of total body surface area). Steroids were extracted from plasma samples and analyzed using multiple reaction monitoring acquisition, with electrospray ionization on a triple quadruple mass spectrometer. Total protein concentration was measured in the samples using spectrophotometry.

Results

Steroid and total protein concentration distributions were compared to reference intervals characteristic of healthy adult men. Concentrations of the following steroids in plasma of burn injured patients were found to correlate positively to the area of the burn injury: cortisol (r = 0.84), corticosterone (r = 0.73), 11-deoxycortisol (r = 0.72), androstenedione (r = 0.72), 17OH-progesterone (r = 0.68), 17OH-pregnenolone (r = 0.64) and pregnenolone (r = 0.77). Concentrations of testosterone decreased during the acute phase and were up to ten-times lower than reference values for healthy adult men, while concentrations of estrone were elevated. By day 21 after injury, testosterone concentrations were increased in younger, but not older, patients. The highest concentrations of estrone were observed on day 3 after the injury and then declined by day 21 to concentrations comparable to those observed on the day of the injury.

Conclusion

Burn injury alters endogenous steroid biosynthesis, with decreased testosterone concentrations and elevated estrone concentrations, during the first 21 days after the injury. Concentrations of glucocorticoids, progestagens and androgen precursors correlated positively with the area of burn injury. The finding of increased estrone following burn injury needs to be confirmed in a larger hypothesis-driven study.

Exploratory study of the association of steroid profiles in stimulated ovarian follicular fluid with outcomes of IVF treatment

Steroid concentrations in stimulated follicular fluid (sFF) samples have been linked to the quality of oocytes used in IVF treatments. Most of the published studies focused on evaluating the association of the IVF outcomes with only a few of the steroids, measured by immunoassays (IA). We performed a treatment outcome, prospective cohort study using stimulated FF sampled from 14 infertile women undergoing IVF treatment; single oocyte was used per IVF cycle. Fourteen endogenous steroids were analyzed in 22 ovarian follicle aspirations, which corresponded to the embryos used in the IVF. Ten oocytes were associated with live birth (LB) and 12 with no pregnancy (NP). Steroids were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. Differences in distribution of concentrations in association with the pregnancy outcome (LB or NP), and receiver operating characteristic (ROC) curves analysis were performed for the entire cohort and for within-women data. The predominant androgen and estrogen in stimulated sFF were androstenedione (A4) and estradiol (E2), respectively. Lower concentrations of pregnenolone (Pr), lower ratios of A4/ dehydroepiandrosterone (DHEA), testosterone (Te)/DHEA, and greater ratios of E2/Te, and estrone/A4 were observed in sFF samples associated with LB. Among the oocytes associated with NP, in four out of 12 samples total concentration of androgens was above the distribution of the concentrations in the oocytes corresponding to the LB group. Observations of the study indicated increased consumption of precursors and increased biosynthesis of estrogens in the follicles associated with LB. Our data suggest that potentially steroid profiles in sFF obtained during oocyte retrieval may serve as biomarkers for selection of the best embryo to transfer after IVF.

Liquid chromatography-tandem mass spectrometric analysis of ten estrogen metabolites at sub-picogram levels in breast cancer women

The measurement of estrogens at sub-picogram levels is essential for research on breast cancer and postmenopausal plasma. Heretofore, these concentration levels have rarely been achieved. However, it is possible through derivatization but still represent problems for monitoring catechol estrogens and 16α-hydroxyestrone (16α-OH-E1). Estrogens possess poor ionization efficiency in MS/MS, which results in insufficient sensitivity for analyzing samples at trace concentrations. The method presented here was used to extract ten estrogen metabolites (EMs) with a derivatization step involving a new adduct. The electrospray ionization (ESI) MS/MS sensitivity for the EMs was enhanced by derivatization with 3-bromomethyl-propyphenazone (BMP). The lower limits of quantification (LLOQ) of the EMs were 12-100 femtogram on-column, equivalent to 0.3-3.6pg/mL plasma, and the limits of detection (LOD) were 0.1-0.8pg/mL plasma. The percentage coefficient of variation (CV%) at the LLOQ was <20 for all investigated EMs. Ionization suppression was minimized by reacting the excess reagent, BMP, with methanol. The method was successfully applied for the determination of ten EMs in the plasma of fifty healthy postmenopausal and fifty ductal breast cancer women aged 47-65 years old. 16α-OH-E1 and three catechol estrogen metabolites, 4-OH-E1, 2-OH-E2 and 4-OH-E2, were successfully measured in the plasma of healthy and breast cancer women. The methyl-propyphenazone-EM derivatives exhibited better sensitivity in ESI-MS (7.5-fold) compared to the commonly used dansylation procedure.

High-Sensitivity Micro LC-MS/MS Assay for Serum Estradiol without Derivatization

Background

There are considerable demands to accurately measure estradiol (E2) at low concentrations (&lt;20 pg/mL) in postmenopausal women, men, pediatric patients, and patients receiving breast cancer treatment. Most current high-sensitivity LC-MS/MS E2 methods require large sample volumes and involve complex sample preparations with dansyl chloride derivatization. Our study aims to develop a high-sensitivity, underivatized method using micro LC-MS/MS to reliably measure E2 concentrations below 5 pg/mL by the use of low sample volume.

Methods

A total of 290 μL of sample was mixed with internal standard (IS), E2-d4, and extracted with a mixture of hexane/ethyl acetate (90/10) (v/v). After extraction, sample was separated by Eksigent Ekspert™ micro LC 200 system with a flow rate of 35 μL/min in a total run time of 3.5 min and detected by SCIEX QTRAP 6500 mass spectrometer in a negative mode using transitions: 271/145 (quantifier) and 271/143 (qualifier). In this method, it was crucial to use HPLC columns with stability at a pH &gt;10.

Results

The validation study demonstrated broad linear ranges (3.0–820.0 pg/mL) with r2 &gt; 0.999. Total precision was below 15% at all QC levels, and limit of quantification (LOQ) was 3.0 pg/mL. Our method showed good correlation with E2 RIA (r2 = 0.96, bias = −1.0 pg/mL) and modest correlation with E2 Roche Cobas automated immunoassay (r2 = 0.86, bias = 6.0 pg/mL).

Conclusions

In conclusion, we developed and validated a routinely applicable micro LC-MS/MS method without derivatization for E2 in blood samples with an LOQ of 3.0 pg/mL.

Advances in bioanalytical techniques to measure steroid hormones in serum

Steroid hormones are measured clinically to determine if a patient has a pathological process occurring in the adrenal gland, or other hormone responsive organs. They are very similar in structure making them analytically challenging to measure. Additionally, these hormones have vast concentration differences in human serum adding to the measurement complexity. GC–MS was the gold standard methodology used to measure steroid hormones clinically, followed by radioimmunoassay, but that was replaced by immunoassay due to ease of use. LC–MS/MS has now become a popular alternative owing to simplified sample preparation than for GC–MS and increased specificity and sensitivity over immunoassay. This review will discuss these methodologies and some new developments that could simplify and improve steroid hormone analysis in serum.

A MALDI-MS-based quantitative analytical method for endogenous estrone in human breast cancer cells

The level of endogenous estrone, one of the three major naturally occurring estrogens, has a significant correlation with the incidence of post-menopausal breast cancer. However, it is challenging to quantitatively monitor it owing to its low abundance. Here, we develop a robust and highly sensitive mass-assisted laser desorption/ionization mass spectrometry (MALDI-MS)-based quantitative platform to identify the absolute quantities of endogenous estrones in a variety of clinical specimens. The one-step modification of endogenous estrone provided good linearity (R(2) > 0.99) and significantly increased the sensitivity of the platform (limit of quantitation: 11 fmol). In addition, we could identify the absolute amount of endogenous estrones in cells of the breast cancer cell line MCF-7 (34 fmol/10(6) cells) by using a deuterated estrone as an internal standard. Finally, by applying the MALDI-MS-based quantitative method to endogenous estrones, we successfully monitored changes in the metabolic expression level of estrones (17.7 fmol/10(6) letrozole-treated cells) in MCF-7 cells resulting from treatment with an aromatase inhibitor. Taken together, these results suggest that this MALDI-MS-based quantitative approach may be a general method for the targeted metabolomics of ketone-containing metabolites, which can reflect clinical conditions and pathogenic mechanisms.

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.

Advanced Running Performance by Genetic Predisposition in Male Dummerstorf Marathon Mice (DUhTP) Reveals Higher Sterol Regulatory Element-Binding Protein (SREBP) Related mRNA Expression in the Liver and Higher Serum Levels of Progesterone

Long-term-selected DUhTP mice represent a non-inbred model for inborn physical high-performance without previous training. Abundance of hepatic mRNA in 70-day male DUhTP and control mice was analyzed using the Affymetrix mouse array 430A 2.0. Differential expression analysis with PLIER corrected data was performed using AltAnalyze. Searching for over-representation in biochemical pathways revealed cholesterol metabolism being most prominently affected in DUhTP compared to unselected control mice. Furthermore, pathway analysis by AltAnalyze plus PathVisio indicated significant induction of glycolysis, fatty acid synthesis and cholesterol biosynthesis in the liver of DUhTP mice versus unselected control mice. In contrast, gluconeogenesis was partially inactivated as judged from the analysis of hepatic mRNA transcript abundance in DUhTP mice. Analysis of mRNA transcripts related to steroid hormone metabolism inferred elevated synthesis of progesterone and reduced levels of sex steroids. Abundance of steroid delta isomerase-5 mRNA (Hsd3b5, FC 4.97) was increased and steroid 17-alpha-monooxygenase mRNA (Cyp17a1, FC -11.6) was massively diminished in the liver of DUhTP mice. Assessment of steroid profiles by LC-MS revealed increased levels of progesterone and decreased levels of sex steroids in serum from DUhTP mice versus controls. Analysis of hepatic mRNA transcript abundance indicates that sterol regulatory element-binding protein-1 (SREBP-1) may play a major role in metabolic pathway activation in the marathon mouse model DUhTP. Thus, results from bioinformatics modeling of hepatic mRNA transcript abundance correlated with direct steroid analysis by mass spectrometry and further indicated functions of SREBP-1 and steroid hormones for endurance performance in DUhTP mice.

Mass spectrometry methods measured androgen and estrogen concentrations during pregnancy and in newborns of mothers with polycystic ovary syndrome

OBJECTIVE

Little is known about the aetiology of polycystic ovary syndrome (PCOS). Some suggest that elevated maternal androgens during gestation play a causative role. This implies placental passage of androgens during pregnancy. The aim of this study is to compare androgen and estrogen concentrations in maternal serum during pregnancy and in umbilical cord blood, between mothers with PCOS and their offspring compared to controls.

DESIGN

Prospective case-control study.

METHODS

Maternal blood samples were collected around 20 weeks of gestation and at delivery. Umbilical cord blood was also taken at delivery. Androgens (testosterone (T), androstenedione (ADION), dehydroepiandrostenedione (DHEA)) and estrogens (estrone (E1), estradiol (E2), estriol (E3)) were measured using the liquid chromatography tandem mass spectrometry (LC-MS/MS) methods.

RESULTS

At 20 weeks of gestation: T (P=0.019) and ADION (P=0.034) were higher in the PCOS mothers (pregnant with a girl), whereas DHEA, E1, E2, and E3 were not different. Maternal concentration at birth: T (P=0.004) and ADION (P=0.009) were also higher in the subgroup of PCOS mothers that were pregnant with a girl compared to the girl pregnancy controls. DHEA, E1, E2 and E3 were not different. In umbilical cord blood, no differences were found for T, ADION, DHEA, E2, E3, and AMH between the PCOS mothers and the controls respectively. E1 was lower in girls from PCOS mothers (P=0.007).

CONCLUSIONS

Despite elevated maternal androgen concentrations during pregnancy in PCOS mothers, offspring showed no signs of elevated androgen concentrations in cord blood at birth using the latest highly specific LC-MS/MS methods.

Direct Measurement of Free Estradiol in Human Serum and Plasma by Equilibrium Dialysis-Liquid Chromatography-Tandem Mass Spectrometry

We describe a direct method of measurement of free estradiol using equilibrium dialysis followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum aliquots and internal standards are extracted by liquid-liquid extraction using methyl-tert-butyl ether (MTBE) followed by derivatization with dansyl chloride. An API 5500 mass spectrometer operated in positive electrospray mode is used for detection.

Simultaneous Quantitation of Estradiol and Estrone in Serum Using Liquid Chromatography Mass Spectrometry

Accurate measurement of the endogenous estrogens, estrone (E1) and estradiol (E2), is important in the clinical diagnosis and monitoring of multiple disorders. Typically, given the efficacy and low cost, radioimmunoassays (RIA) and enzyme-linked immunoassays (EIA) are used to quantify these hormones in biological samples. Unfortunately, at low levels these assays lack the necessary sensitivity and specificity for diagnosis of certain disorders in adult and pediatric endocrinology and oncology. In response to this need, we developed a fast and sensitive high performance liquid chromatography negative electrospray ionization tandem mass spectrometry (LC-MS/MS) method to measure serum estrone (E1) and estradiol (E2) without chemical derivatization. Samples are spiked with a stable isotopic carbon thirteen ((13)C) labeled internal standard and the estrogens are isolated by liquid-liquid extraction (LLE) with hexane:Methyl-tert-butyl ether (MTBE) (9:1). Following centrifugation and dry down samples are reconstituted with deionized water, and separated on a C18 reverse phase column. The analytes are quantified using a six point calibration curve with a linearity of 2.6-625 pg/ml and with a variability of less than 8 % across analytical range.

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.

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

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

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Methylpyridinium ether derivatives improve analytical specificity and sensitivity.

Urinary Sex Steroids and Anthropometric Markers of Puberty - A Novel Approach to Characterising Within-Person Changes of Puberty Hormones

Background/Aims

The longitudinal relationships of within-individual hormone and anthropometric changes during puberty have not ever been fully described. The objectives of this study were to demonstrate that 3 monthly urine collection was feasible in young adolescents and to utilise liquid chromatography-tandem mass spectrometry assay methods for serum and urine testosterone (T), estradiol (E₂) and luteinizing hormone (LH) in adolescents by relating temporal changes in urine and serum hormones over 12 months to standard measures of pubertal development.

Methods

A community sample of 104 adolescents (57 female) was studied over 12 months with annual anthropometric assessment, blood sampling and self-rated Tanner staging and urine collected every 3 months. Serum and urine sex steroids (T, E₂) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and LH by immunoassay.

Results

A high proportion (92%) of scheduled samples were obtained with low attrition rate of 6.7% over the 12 months. Urine hormone measurements correlated cross-sectionally and longitudinally with age, anthropometry and Tanner stage.

Conclusion

We have developed a feasible and valid sampling methodology and measurements for puberty hormones in urine, which allows a sampling frequency by which individual pubertal progression in adolescents can be described in depth.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for analysis of endogenous steroids in the luteal phase and early pregnancy in dogs: a pilot study

BACKGROUND

Blood samples from dogs are often limited in volume, only allowing few steroids to be quantified with immunoassays. In addition, immunoassays may be compromised by interferences such as anti-reagent antibodies. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can be used for the simultaneous quantitation of several steroids. This has not been described in dogs before.

OBJECTIVES

The aims were to use LC-MS/MS to study steroid profiles in early pregnancy and luteal phase in dogs, and to determine if differences exist between pregnant (P) and nonpregnant (NP) dogs.

METHODS

Nine female dogs were included, 4 during a NP luteal phase, 4 during a P luteal phase, and one during one NP and one P luteal phase. Blood samples were collected around the time of the LH surge (Day 0) and on Day 26. Serum was analyzed for 5 classes of steroids, including glucocorticoids, androgens, estrogens, pregnanes, and progestins, using LC-MS/MS methods.

RESULTS

The concentration of progesterone was significantly higher on Day 26 in P than in NP bitches. Distribution of concentrations of glucocorticoids, androgens, estrogens, or pregnanes in P and NP dogs were not statistically different. The predominating glucocorticoid was cortisol, and dihydroepiandrosterone (DHEA) was the predominating androgen. Concentration of estrone was comparable to oestradiol, whereas concentrations of pregnenolone were higher than those of 17-OH pregnenolone.

CONCLUSIONS

Only concentration of progesterone differed between P and NP bitches, being significantly higher on Day 26 in P than in NP bitches. LC-MS/MS offers interesting possibilities for studies of canine reproductive endocrinology.

Bioanalytical validation for simultaneous quantification of non-aromatic steroids in follicular fluid from cattle via ESI-LC-MS/MS

The family of steroid hormones is quite attractive for the approach of phenotype monitoring in farm animals. Therefore, we developed a new protocol for the quantitative analysis of natural steroids in follicular fluid from dairy cows. The corresponding steroid profile, which consists of progesterone, corticosterone, hydrocortisone, testosterone, and androstenedione covering three distinct steroid classes, was determined by LC/MS. Quantification is achieved by use of steroid standards diluted in steroid-free follicular fluid as calibrators. Thus, the new protocol does not require deuterated standards. In order to correct for conditional performance of the analytical system we have used dexamethasone as an internal standard. The method was validated according to EMA guidelines. Within- and between-day variations were below 20% for most parameters assessed. All steroids assessed had lower limits of quantification in the range of 2.1 to 4.4ng/ml. We have established a simple and sensitive analytical system in order to step towards a broader and cost-efficient phenotyping analysis in follicular fluid from dairy cows.

Derivatization of steroids in biological samples for GC–MS and LC–MS analyses

The determination of steroids in biological samples is essential in different areas of knowledge. MS combined with either GC or LC is considered the best analytical technique for specific and sensitive determinations. However, due to the physicochemical properties of some steroids, and the low concentrations found in biological samples, the formation of a derivative prior to their analysis is required. In GC–MS determinations, derivatization is needed for generating volatile and thermally stable compounds. The improvement in terms of stability and chromatographic retention are the main reasons for selecting the derivatization agent. On the other hand, derivatization is not compulsory in LC–MS analyses and the derivatization is typically used for improving the ionization and therefore the overall sensitivity achieved.

Current status and recent advantages in derivatization procedures in human doping control

Derivatization is one of the most important steps during sample preparation in doping control analysis. Its main purpose is the enhancement of chromatographic separation and mass spectrometric detection of analytes in the full range of laboratory doping control activities. Its application is shown to broaden the detectable range of compounds, even in LC–MS analysis, where derivatization is not a prerequisite. The impact of derivatization initiates from the stage of the metabolic studies of doping agents up to the discovery of doping markers, by inclusion of the screening and confirmation procedures of prohibited substances in athlete's urine samples. Derivatization renders an unlimited number of opportunities to advanced analyte detection.

Derivatization of bisphenol A and its analogues with pyridine-3-sulfonyl chloride: multivariate optimization and fragmentation patterns by liquid chromatography/Orbitrap mass spectrometry

RATIONALE

Due to the growing restrictions on the use of bisphenol A (BPA), several other bisphenols are gaining importance as substitutes for BPA in a variety of applications. There is, therefore, a real need for selective and sensitive methods based on mass spectrometry which will allow the human exposure to these new bisphenols to be assessed.

METHODS

Derivatization of BPA and its substitutes with pyridine-3-sulfonyl chloride is used to enhance the detection capability of bisphenols by electrospray ionization mass spectrometry. A multivariate experimental design, Box-Behnken response surface, was used to evaluate the influence of the main variables potentially affecting the derivatization yield. Fragmentation patterns for all the derivatized bisphenols were acquired by high-resolution/accurate-mass Orbitrap mass spectrometry.

RESULTS

Temperature and pH were identified as the most important factors affecting the derivatization yield of bisphenols. Fragmentation of the protonated molecules produced abundant analyte-specific product ions. Most of the derivatized bisphenols showed significant improvements in their signal-to-noise ratios compared with the underivatized forms. The stability of these derivatives was demonstrated through several freeze/thaw cycles, short-term room temperature and long-term cold storage.

CONCLUSIONS

Derivatization of BPA and its structural analogues with pyridine-3-sulfonyl chloride is proposed as a specific, sensitive, high-throughput approach to their analysis by liquid chromatography coupled to electrospray ionization mass spectrometry.

Comparative study of two types of herbal capsules with different Epimedium species for the prevention of ovariectomised-induced osteoporosis in rats

Background/Objective

Epimedii Folium is the most important osteogenic herb formulated for the traditional Chinese Medicine Xian Ling Gu Bao (XLGB) capsule. The present study compared XLGB capsules containing two different Epimedium species, i.e., either Epimedium pubescens (XEP) or Epimedium koreanum (XEK), with the focus being on the chemical constituents and antiosteoporotic efficacy.

Methods

Ultra performance liquid chromatography was used to demonstrate the different chemical constituents. Biomechanical tests, histological, and cytological evaluation were performed to characterise and compare the bone mineral density, bone strength, microstructure of bone tissue, and biological activity between XEP and XEK using an established ovariectomised (OVX) rat model.

Results

Six flavonoids with different contents between XEK and XEP were identified. As compared with the OVX group, significantly higher bone mineral density, elastic-modulus, and compressive strength were found in both the XEK group and XEP group (p < 0.05 for all, n = 8). Histomorphometric data presented significantly higher osteoblast surface ratio and osteoid area accompanied by significantly lower values of erosion surface and adiopocytes area in two treatment groups (p < 0.05, n = 6). XLGB Fufang with either XEK or XEP all showed significant preventive effects in OVX-induced osteoporosis and deterioration of bone mechanical properties.

Conclusion

The significance of the current preclinical experimental study was that these two Epimedium species used for formulating XLGB capsules were equally effective for the prevention of oestrogen-depletion induced osteoporosis.

Measurement of Estradiol in Human Serum by LC-MS/MS Using a Novel Estrogen-Specific Derivatization Reagent

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is described that employs a novel derivatization reagent for the measurement of serum estradiol (E2), with simultaneous analysis of underivatized testosterone (T) and dihydrotestosterone (DHT). The main advantage of the new derivatization reagent 1,2-dimethylimidazole-5-sulfonyl chloride is its analyte-specific fragmentation that enables monitoring of confirmatory mass transitions with high sensitivity. The reaction mixture can be analyzed without additional purification steps using a 9.5 min gradient run, and sensitive detection is achieved with a triple quadrupole mass spectrometer using atmospheric pressure photoionization. Method validation was performed with human serum samples, including a comparison with a standard LC-MS/MS method using 120 samples from a clinical study, and analysis of certified E2 serum reference materials BCR-576, BCR-577, and BCR-578. The lower limits of quantification for E2, T, and DHT were 0.5 pg/mL, 25 pg/mL, and 0.10 ng/mL, respectively, from a 200-μL sample. Validation results indicated good accuracy and agreement with established, conventional LC-MS/MS assays, demonstrating suitability for analysis of samples containing E2 in the low pg/mL range, such as serum from men, children, and postmenopausal women.

Improved profiling of estrogen metabolites by orbitrap LC/MS

Estrogen metabolites are important biomarkers to evaluate cancer risks and metabolic diseases. Due to their low physiological levels, a sensitive and accurate method is required, especially for the quantitation of unconjugated forms of endogenous steroids and their metabolites in humans. Here, we evaluated various derivatives of estrogens for improved analysis by orbitrap LC/MS in human serum samples. A new chemical derivatization reagent was applied modifying phenolic steroids to form 1-methylimidazole-2-sulfonyl adducts. The method significantly improves the sensitivity 2-100 fold by full scan MS and targeted selected ion monitoring MS over other derivatization methods including, dansyl, picolinoyl, and pyridine-3-sulfonyl products.

Analysis of estrogens and androgens in postmenopausal serum and plasma by liquid chromatography-mass spectrometry

Liquid chromatography-selected reaction monitoring/mass spectrometry-based methodology has evolved to the point where accurate analyses of trace levels of estrogens and androgens in postmenopausal serum and plasma can be accomplished with high precision and accuracy. A suite of derivatization procedures has been developed, which together with modern mass spectrometry instrumentation provide investigators with robust and sensitive methodology. Pre-ionized derivatives are proving to be useful as they are not subject to suppression of the electrospray signal. Postmenopausal women with elevated plasma or serum estrogens are thought to be at increased risk for breast and endometrial cancer. Therefore, significant advances in risk assessment should be possible now that reliable methodology is available. It is also possible to conduct analyses of multiple estrogens in plasma or serum. Laboratories that are currently employing liquid chromatography/mass spectrometry methodology can now readily implement this strategy. This will help conserve important plasma and serum samples available in Biobanks, as it will be possible to conduct high sensitivity analyses using low initial sample volumes. Reported levels of both conjugated and non-conjugated estrogen metabolites are close to the limits of sensitivity of many assays to date, urging caution in the interpretation of these low values. The analysis of serum androgen precursors in postmenopausal women has not been conducted routinely in the past using liquid chromatography/mass spectrometry methodology. Integration of serum androgen levels into the panel of metabolites analyzed could provide additional information for assessing cancer risk and should be included in the future.

International Union of Basic and Clinical Pharmacology. XCVII. G Protein-Coupled Estrogen Receptor and Its Pharmacologic Modulators

Estrogens are critical mediators of multiple and diverse physiologic effects throughout the body in both sexes, including the reproductive, cardiovascular, endocrine, nervous, and immune systems. As such, alterations in estrogen function play important roles in many diseases and pathophysiological conditions (including cancer), exemplified by the lower prevalence of many diseases in premenopausal women. Estrogens mediate their effects through multiple cellular receptors, including the nuclear receptor family (ERα and ERβ) and the G protein-coupled receptor (GPCR) family (GPR30/G protein-coupled estrogen receptor [GPER]). Although both receptor families can initiate rapid cell signaling and transcriptional regulation, the nuclear receptors are traditionally associated with regulating gene expression, whereas GPCRs are recognized as mediating rapid cellular signaling. Estrogen-activated pathways are not only the target of multiple therapeutic agents (e.g., tamoxifen, fulvestrant, raloxifene, and aromatase inhibitors) but are also affected by a plethora of phyto- and xeno-estrogens (e.g., genistein, coumestrol, bisphenol A, dichlorodiphenyltrichloroethane). Because of the existence of multiple estrogen receptors with overlapping ligand specificities, expression patterns, and signaling pathways, the roles of the individual receptors with respect to the diverse array of endogenous and exogenous ligands have been challenging to ascertain. The identification of GPER-selective ligands however has led to a much greater understanding of the roles of this receptor in normal physiology and disease as well as its interactions with the classic estrogen receptors ERα and ERβ and their signaling pathways. In this review, we describe the history and characterization of GPER over the past 15 years focusing on the pharmacology of steroidal and nonsteroidal compounds that have been employed to unravel the biology of this most recently recognized estrogen receptor.

Estradiol assays--The path ahead

Estradiol quantitation is useful in the clinical assessment of diseases like hypogonadism, hirsutism, polycystic ovary syndrome (PCOS), amenorrhea, ovarian tumors and for monitoring response in women receiving aromatase inhibitor therapy. Physiologically relevant serum estradiol concentration in women can span across four orders of magnitude. For example, in women undergoing ovulation induction serum estradiol concentration can range between 250-2000 pg/mL whereas aromatase inhibitor therapy can decrease serum estradiol concentration to <5 pg/mL. While high-through-put automated un-extracted (direct) immunoassays accommodate the growing clinical need for estradiol quantitation, are amenable to implementation by most hospital clinical laboratories, they display a significant loss of specificity and accuracy at low concentrations. Most clinical scenarios (example: estradiol monitoring in fertility treatments) place a modest demand on accuracy and precision of the assay in use but accurate quantitation of estradiol in certain clinical scenarios (pediatric and male patients and for monitoring aromatase inhibitor therapy) can be challenging using currently available immunoassays since the direct immunoassays are prone to issues with sub-optimal accuracy and specificity due to cross reactivity with estradiol conjugates and metabolites. In this review we discuss the bases for the evolution of estradiol assays from extracted (indirect) radio-immunoassays to direct immunoassays to liquid-chromatography tandem mass spectrometry (LC-MS/MS) based assays, discuss technical factors relevant for development and optimization of a LC-MS/MS assay for estradiol and present the details and performance characteristics of an ultra-sensitive LC-MS/MS estradiol assay with a limit of quantitation of 0.2 pg/mL.

Relationship between Serum Testosterone and Fracture Risk in Men: A Comparison of RIA and LC-MS/MS

BACKGROUND

Serum testosterone can be measured by LC-MS/MS and RIA. We investigated whether the testosterone-fracture relationship was affected by the method of measurement.

METHODS

We measured total testosterone (TT) by LC-MS/MS (TTLC-MS/MS) and RIA (TTRIA) in serum samples collected from 602 men whose incident fractures had been continuously ascertained by x-ray reports from 1989 to 2010. We measured bone mineral density (BMD) by dual-energy x-ray absorptiometry. The association between TT and fracture risk was assessed by the Cox proportional hazards model, taking into account the effect of age and BMD.

RESULTS

Mean TTLC-MS/MS was higher than TTRIA by 27 ng/dL (95% CI 13-41). The concordance correlation coefficient between TTLC-MS/MS and TTRIA was 0.72 (95% CI 0.68-0.76). The Deming regression equation linking the 2 measurements was ln(TTLC-MS/MS + 10) = 0.87 + 0.87 × ln(TTRIA + 10). The hazard ratio of fracture per SD decrease in TT was 1.32 (95% CI 1.12-1.54) for TTLC-MS/MS and 1.23 (1.06-1.43) for TTRIA. The correlation between predicted probabilities of fracture by TTLC-MS/MS and TTRIA was r = 0.96, with the mean difference being 0.01% (95% CI -6.1% to 6.2%). Slightly more patients were classified as having hypogonadism if TTRIA was used (29% vs 26%).

CONCLUSIONS

The concordance between LC-MS/MS and RIA in the measurement of serum TT was moderate. Moreover, the magnitude of association between testosterone and fracture risk in older men was largely unaffected by the method of measurement.

Prediction of gestational age-dependent induction of in vivo hepatic CYP3A activity based on HepaRG cells and human hepatocytes

In pregnant women, CYP3A activity increases by 100% during the third trimester (T3). Due to logistical and ethical constraints, little is known about the magnitude of CYP3A induction during the first trimester (T1) and second trimester (T2). Our laboratory has shown that sandwich-cultured human hepatocytes (SCHH) and HepaRG cells have the potential to predict the magnitude of in vivo induction of CYP3A activity likely to be observed in T1 and T2. Therefore, we incubated SCHH and HepaRG cells with plasma concentrations of various pregnancy-related hormones (PRHs)-individually or in combination-observed during T1, T2, or T3 in pregnant women. Then, CYP3A activity was measured by 1'-OH-midazolam formation. In all three trimesters, only cortisol (C) consistently and significantly induced CYP3A activity, while other individual hormones (progesterone, estradiol, or growth hormones) failed to induce CYP3A activity. At physiologically relevant 1× plasma concentrations, the magnitude of CYP3A induction by C or the combination of all PRHs did not change significantly with gestational age. The pattern of induction of CYP3A activity in SCHH by the hormones was similar to that in HepaRG cells. Based on these data, we conclude that C remains the major inducer of CYP3A activity earlier in gestation. Moreover, we predict that the magnitude of CYP3A induction during T1 and T2 will be similar to that observed during T3 (∼100% increase versus postpartum). This prediction is consistent with the observation of similar increases in T2 and T3 oral clearance of indinavir (a CYP3A cleared drug) versus postpartum.

Accurate and sensitive liquid chromatography/tandem mass spectrometry simultaneous assay of seven steroids in monkey brain

BACKGROUND

Following its secretion mainly by the adrenal glands, dehydroepiandrosterone (DHEA) acts primarily in the cells/tissues which express the enzymes catalyzing its intracellular conversion into sex steroids by the mechanisms of intracrinology. Although reliable assays of endogenous serum steroids are now available using mass spectrometry (MS)-based technology, sample preparation from tissue matrices remains a challenge. This is especially the case with high lipid-containing tissues such as the brain. With the combination of a UPLC system with a sensitive tandem MS, it is now possible to measure endogenous unconjugated steroids in monkey brain tissue.

METHODS

A Shimadzu UPLC LC-30AD system coupled to a tandem MS AB Sciex Qtrap 6500 system was used.

RESULTS

The lower limits of quantifications are achieved at 250 pg/mL for DHEA, 200 pg/mL for 5-androstenediol (5-diol), 12 pg/mL for androstenedione (4-dione), 50 pg/mL for testosterone (Testo), 10 pg/mL for dihydrotestosterone (DHT), 4 pg/mL for estrone (E1) and 1 pg/mL for estradiol (E2). The linearity and accuracy of quality controls (QCs) and endogenous quality controls (EndoQCs) are according to the guidelines of the regulatory agencies for all seven compounds.

CONCLUSION

We describe a highly sensitive, specific and robust LC-MS/MS method for the simultaneous measurement of seven unconjugated steroids in monkey brain tissue. The single and small amount of sample required using a relatively simple preparation method should be useful for steroid assays in various peripheral tissues and thus help analysis of the role of locally-made sex steroids in the regulation of specific physiological functions.

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

BACKGROUND

A high-throughput, sensitive, specific, mass spectrometry-based method for quantitating estrone (E1), estradiol (E2), and testosterone (T) in postmenopausal human serum has been developed for clinical research. The method consumes 100μl human serum for each measurement (triplicates consume 300μl) and does not require derivatization. We adapted a commercially available 96-well plate for sample preparation, extraction, and introduction into the mass spectrometer on a single platform.

METHODS

Steroid extraction from serum samples and mass spectrometer operational parameters were optimized for analysis of estradiol and subsequently applied to other analytes. In addition to determining the limit of detection (LOD) and limit of quantitation (LOQ) from standard curves, a serum LOQ (sLOQ) was determined by addition of known steroid quantities to serum samples. Mass spectrometric method quantitative data were compared to results using a state-of-the-art ELISA (enzyme-linked immunosorbent assay) using stored serum samples from menopausal women.

RESULTS

The LOD, LOQ, sLOQ was (0.1pg, 0.3pg, 1pg/ml) for estrone, (0.3pg, 1pg, 3pg/ml) for estradiol, and (0.3pg, 1pg, 30pg/ml) for testosterone, respectively. Mass spectrometry accurately determined concentrations of E2 that could not be quantified by immunochemical methods. E1 concentrations measured by mass spectrometry were in all cases significantly lower than the ELISA measurements, suggesting immunoreactive contaminants in serum may interfere with ELISA. The testosterone measurements broadly agreed with each other in that both techniques could differentiate between low, medium and high serum levels.

CONCLUSIONS

We have developed and validated a scalable, sensitive assay for trace quantitation of E1, E2 and T in human serum samples in a single assay using sample preparation method and stable isotope dilution mass spectrometry.

Ultrasensitive quantification of serum estrogens in postmenopausal women and older men by liquid chromatography-tandem mass spectrometry

An ultrasensitive stable isotope dilution liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for multiplexed quantitative analysis of six unconjugated and conjugated estrogens in human serum. The quantification utilized a new derivatization procedure, which formed analytes as pre-ionized N-methyl pyridinium-3-sulfonyl (NMPS) derivatives. This method required only 0.1mL of human serum, yet was capable of simultaneously quantifying six estrogens within 20min. The lower limit of quantitation (LLOQ) for estradiol (E2), 16α-hydroxy (OH)-E2, 4-methoxy (MeO)-E2 and 2-MeO-E2 was 1fg on column, and was 10fg on column for 4-OH-E2 and 2-OH-E2. All analytes demonstrated a linear response from 0.5 to 200pg/mL (5-2000pg/mL for 4-OH-E2 and 2-OH-E2). Using this validated method, the estrogen levels in human serum samples from 20 female patients and 20 male patients were analyzed and compared. The levels found for unconjugated serum E2 from postmenopausal women (mean 2.7pg/mL) were very similar to those obtained by highly sensitive gas chromatography-mass spectrometry (GC-MS) methodology. However, the level obtained in serum from older men (mean 9.5pg/mL) was lower than has been reported previously by both GC-MS and LC-MS procedures. The total (unconjugated+conjugated) 4-MeO-E2 levels were significantly higher in female samples compared with males (p<0.05). The enhanced sensitivity offered by the present method will allow for a more specific analysis of estrogens and their metabolites. Our observations might suggest that the level of total 4-MeO-E2 could be a potential biomarker for breast cancer cases.

Breaking the sensitivity limitations of cytochrome P450 oxidation product: dansyl chloride derivatisation of 4-OH mephenytoin, a CYP2C19 metabolite and its application to in vitro CYP inhibition assay

A rapid selective and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the quantitative determination of derivatised cytochrome P450-2C19 oxidation product (dansyl-4-OH mephenytoin) and its underivatised form (4-OH mephenytoin). Samples were anaysed on C18 column (Waters Xbridge, 50 mm×4.6 mm, 3.5 μm particle size) with the mobile phase consisting of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. A gradient method with a short run time of 2.5 min and 3.5 min was developed for the analysis of dansyl-4-OH mephenytoin and 4-OH mephenytoin, respectively. The standard curve was linear (r(2)=0.9972 for 4-OH mephenytoin; r(2)=0.9946 for dansyl-4-OH mephenytoin) over the concentration range of 0.16 to 40 ng/mL for both derivatised and underivatised forms. The CV (%) and relative error (RE) for inter and intraassay at three QC levels for dansyl-4-OH mephenytoin was 0.97-5.85% and -9.80 to 2.51%, respectively. Whereas, for 4-OH mephenytoin the CV (%) and RE (%) at three QC levels was 0.82-3.47% and -6.69 to -0.01%, respectively. The developed method was validated for various parameters such as linearity, precision & accuracy, extraction recovery, matrix effect, autosampler stability and was proved to be consistent across three QC levels with overall CV (%) less than 15. Dansylation helped in increasing the sensitivity of hydroxy mephenytoin by 100-200 fold. Given the simplicity involved in derivatisation process, we believe that this novel methodology will change the current approaches used for the enhancing the detection sensitivity of 4-OH mephenytoin.