Liquid chromatography-tandem mass spectrometry assay for human serum testosterone and trideuterated testosterone

Testosterone, free testosterone, and free androgen index in women: Reference intervals, biological variation, and diagnostic value in polycystic ovary syndrome

OBJECTIVE

The objective of our study was to determine reference intervals and biologic variation for testosterone (T), free testosterone (fT), and free androgen index (FAI) in women with accurate methods and to test the discriminative value of these parameters in a polycystic ovary syndrome (PCOS)-population.

METHODS

Serum was obtained daily during a normal menstrual cycle from 25 healthy women (677 data-points). A single serum sample was obtained from 44 PCOS-patients. T was measured by LC–MS/MS and by Architect® 2nd generation T Immunoassay. Sex hormone-binding globulin was measured to calculate fT and FAI. Results: Reference intervals which were established in healthy women with an ovulatory menstrual cycle were T = 0.3-1.6 nmol/L and 0.5-2.0 nmol/L, fT = 5.2-26 pmol/L and 7.2-33 pmol/L, and FAI = 0.4-2.9 and 0.6-4.4, by LC-MS/MS and immunoassay, respectively. T, fT and FAI were higher in PCOS patients than in controls (p b 0.0001). The areas under the curve of receiver operator characteristic (ROC) plots were not different for T, fT, or FAI when T was measured by LC–MS/MS versus immunoassay based on prediction of PCOS. FAI and fT were the strongest predictors of PCOS.

CONCLUSIONS

When based upon the appropriate reference intervals and ROC analysis, LC-MS/MS and second generation immunoassay have equivalent clinical utility for the diagnosis of PCOS.

Simultaneous quantitation of testosterone and estradiol in human cell line (H295R) by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

The possible interaction of environmental contaminants with the endocrine system has been an environmental concern since the early 1990s. To examine these interactions test guidelines have been introduced by regulatory agencies to screen for possible endocrine active compounds. One of these guidelines is the EPA's OPPTS 890.1550 [Steroidogenesis (Human Cell Line-H295R)]. This guideline requires the quantification of two major biomarkers (testosterone and estradiol) in various biological test systems. Traditional quantitation methodologies such as Radioimmunoassay (RIA) and Enzyme-linked Immunosorbent Assay (ELISA) have been used to quantify low levels of steroids. However, those methodologies have drawbacks such as the radioactive safety, antibody availability, separate assay for each biomarker, and lack of selectivity. In the current study, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry method (LC/APPI-MS/MS) has been developed and validated for the simultaneous quantitation of testosterone and estradiol in the H295R cell line. Briefly, the media from cultured cells was extracted with dichloromethane (CH(2)Cl(2)) containing internal standards of both testosterone-d(3) and estradiol-(13)C(3); then, the extracted organic layer was concentrated down to dryness. The final residue was derivatized with dansyl chloride solution, and directly analyzed by LC/APPI-MS/MS. The calibration curves, with concentration ranging from 10 to 2500 pg/mL, were linear with coefficient >0.99. The lower limits of quantitation for both testosterone and estradiol were 10 pg/mL. This method was successfully validated to support requirements of the current EPA Steroidogenesis guideline. This type of method may also provide value for rapid and precise measurements of these two hormones in other in vitro or in vivo test systems.

High-throughput UHPLC-MS/MS method for the detection, quantification and identification of fifty-five anabolic and androgenic steroids in equine plasma

Anabolic and androgenic steroids (AASs) are synthetic substances related to the primary male sex hormone, testosterone. AASs can be abused in both human and equine sports and, thus, are banned by the International Olympic Committee and the Association of Racing Commissioners International (ARCI). Enforcement of the ban on the use of AASs in racehorses during competition requires a defensible and robust method of analysis. To address this requirement, a high-throughput ultra high-performance liquid chromatography-mass spectrometric (UHPLC-MS) method was developed for the detection, quantification and confirmation of 55 AASs in equine plasma. AASs were recovered from equine plasma samples by liquid-liquid extraction with methyl tert-butyl ether (MTBE). Analytes were chromatographically separated on a sub-2 µm particle size C(18) column with a mobile phase gradient elution and detected by selected-reaction monitoring (SRM) on a triple quadrupole mass spectrometer. AASs with isobaric precursor ions were either chromatographically resolved or mass spectrometrically differentiated by unique precursor-to-product ion transitions. A few of them that could not be resolved by both approaches were differentiated by intensity ratios of three major product ions. All the epimer pairs, testosterone and epitestosterone, boldenone and epiboldenone, nandrolone and epinandrolone, were chromatographically base-line separated. The limit of detection and that of quantification was 50 pg/ml for most of the AASs, and the limit of confirmation was 100-500 pg/ml. Full product ion spectra of AASs at concentrations as low as 100-500 pg/ml in equine plasma were obtained using the triple quadrupole instrument, to provide complementary evidentiary data for confirmation. The method is sensitive and selective for the detection, quantification and confirmation of multiple AASs in a single analysis and will be useful in the fight against doping of racehorses with AASs.

Androgen deficiency in women; role of accurate testosterone measurements

Androgen deficiency in women has been recognized as a distinct clinical syndrome that affects thousands of women particularly women in the postmenopausal period of their life. This syndrome has been described by several names including female androgen deficiency syndrome as well as hypoactive, sexual desire disorder. A recent large survey concerning sexual problems in women also adds personal distress as a potential contributor to the low sexual desire found in some women with sexual dysfunction. Recognition of an androgen deficiency syndrome however, has been controversial and limited to a clinical diagnosis due to the lack of accurate and sensitive methods for measuring androgens in women. Up until now, available methods for measuring the sex steroids have been dependent on antibody based assays that employ a range of different detection systems including the use of isotopes such as tritium and I-125 or chemical signalling molecules that produce chemiluminescence. These assays have become increasingly more sensitive for the measurement of testosterone but are still incapable of providing the proper low-end sensitivity for analyzing testosterone in female blood specimens. Assays for testosterone performed either manually or with highly automated immunoassay instruments have been used to measure testosterone in women but with varying degrees of success. Existing immunoassay-based methods are quite adequate for measuring testosterone levels in males but lack sufficient sensitivity to accurately and reproducibly measure testosterone in females and pre-pubertal children. Recent advances with the use of ultrasensitive methods such as mass spectrometry coupled to either gas or liquid chromatography have improved the technology for measuring testosterone and other low concentration sex steroids like estradiol to the degree that mass spectrometry based methods are now capable of measuring the testosterone levels found in normal women and in women with extremely low levels of testosterone as observed in a true androgen deficiency disorder. This application of mass spectrometry for measuring testosterone should allow clinicians to better define female androgen deficiency and facilitate further investigation in the diagnosis and optimal management of androgen deficiency in women.

Simultaneous quantitation of testosterone, estradiol, ethinyl estradiol, and 11-ketotestosterone in fathead minnow fish plasma by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

In the present work, for the first time, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry (LC/APPI-MS/MS) method has been developed and validated for the simultaneous quantitation of testosterone, estradiol, ethinyl estradiol, and 11-ketotestosterone in fathead minnow fish plasma using no more than 10 microL of plasma. Compounds present in plasma were directly derivatized with dansyl chloride and 25 microL of the derivatized mixture was injected into the LC/APPI-MS/MS system. The gradient chromatographic elution was achieved on an Agilent Zorbax SB-C18 analytical column (2.1 mm x 50 mm, 1.8 microm particle size) with mobile phases consisting of acetonitrile, water and acetic acid. The flow rate was 0.5 to 0.7 mL/min and the total run time was 11.5 min. The lower limits of quantitation for testosterone, estradiol, ethinyl estradiol, and 11-ketotestosterone and were 1, 1, 1, and 2.5 ng/mL, respectively. Intra-batch precision was less than 19.4% and inter-batch precision was less than 11.7% for all four analytes. Accuracy was within 83.5-115.4% of nominal concentrations. This method is used for quantitation of sex steroid levels in fathead minnow tested in endocrine disruptor screening experiments.

Development of highly sensitive quantification method for testosterone and dihydrotestosterone in human serum and prostate tissue by liquid chromatography-electrospray ionization tandem mass spectrometry

We developed highly sensitive detection of testosterone (T) and 5alpha-dihydrotestosterone (DHT) by liquid chromatography-electrospray ionization tandem mass spectrometry using high proton affinitive derivatization of 17beta-hydroxyl group of T and DHT with picolinic acid, mobile phase consisting of MeCN-MeOH-H(2)O-formic acid and conventional octadecylsilica (ODS) column. Purification of the derivatives was carried out using solid-phase extraction with ODS cartridge. By this method, T and DHT were determined simultaneously with limits of quantification (LOQs) of 1 pg/0.2 ml in serum, and T and DHT with LOQs of 0.5 pg and 1 pg/3mg in prostate tissue, respectively, under acceptable assay performance (intra-assay and inter-assay accuracy and precision). The present method provides reliable and reproducible results for quantification of T and DHT in small volumes of serum and prostate samples for diagnosis in prostatic disorders and male climacteric.

The impact of assay sensitivity in the assessment of diseases and disorders in children

Accurate measurement of the low levels of testosterone (T) and estradiol (E(2)) present in normal children and in children with disorders of puberty and sexual development is critical both for appropriate diagnosis and treatment and for clinical research studies. However, measurement of these levels lacks needed precision because of inadequate sensitivity of most commercially available assays and poor accuracy at the low levels found in normal childhood and most disorders. While immunoassays presently do not appear to have the potential to provide more accurate measurements, isotope dilution-gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry techniques offer promise to meet this need to improve clinical care and research.

The impact of assay quality and reference ranges on clinical decision making in the diagnosis of androgen disorders

The Endocrine Society guideline on Androgen Deficiency in Men emphasized that accurate measurement of testosterone (T) levels is central to the diagnosis of androgen deficiency. Similarly, accurate measurements of testosterone levels are important in the diagnosis of androgen disorders in women and children. However, the accuracy of direct radioimmunoassays for the measurement of total T levels has been questioned, especially in the low range prevalent in women, children, and androgen deficient men. Furthermore, reference limits for total and free T levels generated in a population-based sample of community-dwelling men, women, and children are not available. In the absence of standardized reference limits, the partitioning of total and free T levels into normal, low, or high values is fraught with substantial risk of misclassification. The recommendations for partitioning of individuals into those with low, normal, or high levels should be based on considerations of statistical distribution of total and free T values and the association of outcomes with varying degree of deviations from the reference limits. Ongoing efforts to generate population-based reference ranges for total and free testosterone levels in men and women will provide a framework for the interpretation of serum T levels and enhance the comprehensibility of circulating T values to practicing clinicians. These steps will facilitate the development of rational criteria for the diagnosis of androgen disorders in men, women, and children.

Motivations and methods for analyzing pulsatile hormone secretion

Endocrine glands communicate with remote target cells via a mixture of continuous and intermittent signal exchange. Continuous signaling allows slowly varying control, whereas intermittency permits large rapid adjustments. The control systems that mediate such homeostatic corrections operate in a species-, gender-, age-, and context-selective fashion. Significant progress has been made in understanding mechanisms of adaptive interglandular signaling in vivo. Principal goals are to understand the physiological origins, significance, and mechanisms of pulsatile hormone secretion. Key analytical issues are: 1) to quantify the number, size, shape, and uniformity of pulses, nonpulsatile (basal) secretion, and elimination kinetics; 2) to evaluate regulation of the axis as a whole; and 3) to reconstruct dose-response interactions without disrupting hormone connections. This review will focus on the motivations driving and the methodologies used for such analyses.

Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques

BACKGROUND

Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques.

METHODS

Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic immunoassays, and three manual, isotopic immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods.

RESULTS

Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children.

CONCLUSION

None of the immunoassays tested proved sufficiently reliable when low testosterone concentrations (< or =3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

Column-switching LC-MS/MS analysis for quantitative determination of testosterone in human serum

BACKGROUND

An accurate measurement of testosterone is needed in many clinical applications for correct diagnosis and appropriate treatment. Our aim was to develop a fast and robust high-throughput LC-MSMS method for quantification of serum testosterone in women.

METHODS

Testosterone was derivatized by oximation and extracted with methyl tert-butyl ether from 200 microL of serum. Further matrix elimination was achieved on-line using a column-switching LC-method. The instrumental analysis was performed on an API4000 tandem mass spectrometer equipped with an Agilent series 1312A binary pump and an Agilent series 1311A quaternary pump. The MRM transitions were 304-->124 and 304-->112 for testosterone and 307-->124 and 307-->112 for d(3)-testosterone.

RESULTS

The total analysis time of the column-switching method was 3 min. Linear calibration curves were obtained in the concentration range from 0.035 nmol/L (0.01 microg/L) to 6.92 nmol/L (2 microg/L). Within-day and between-day precision, expressed as the relative standard deviation at four different concentrations ranged from 4.70% to 9.35%. Correlation with the in-house method (solvent-extraction RIA) showed r(2)=0.920.

CONCLUSIONS

The presented column-switching method offers a simple, fast and economical analysis of testosterone in human serum. The procedure requires only small sample volumes and is well suited for quantification of testosterone in serum from women and children.

Time-Resolved Fluoroimmunoassay for 19-Nortestosterone Residues in Aquaculture Tissues

A competitive time-resolved fluoroimmunoassay (TR-FIA) was developed for the determination of 19-nortestosterone (17beta-NT) residues in aquaculture tissues. The limit of detection (LOD) was determined to be 0.08 ng g-1 and the limit of quantification (LOQ) was less than 0.8 ng g-1. The results obtained by the TR-FIA and ELISA showed a good correlation. The established TR-FIA was validated for the determination of incurred aquaculture tissues and confirmed by liquid chromatography tandem mass spectrometry (LC/MS/MS). This proposed technique could be applied to routine residue analysis.

Development and validation of a simple reversed-phase high-performance liquid chromatography method for the determination of testosterone in serum of males

An isocratic high-performance liquid chromatographic method with detection at 234 nm was developed, optimized and validated for the determination of testosterone in human serum. Propylparaben was used as internal standard. A Hypersil BDS RP-C18 column (150 mmx4.6 mm, 5 microm), was equilibrated with a mobile phase composed of acetonitrile and water (35:65, v/v) and having a flow rate of 1 ml/min. The elution time for testosterone and internal standard was approximately 11.6 and 9.9 min, respectively. Calibration curves of testosterone in serum were linear in the concentration range of 1-20 ng/ml. Limits of detection and quantification in serum were 0.4 and 1.1 ng/ml, respectively. Recovery was greater than 92%. Intra- and inter-day relative standard deviation for testosterone in serum was less than 2.1 and 3.9%, respectively. This method was applied to the determination of testosterone serum levels of 12 healthy males and data were correlated with data obtained using a radioimmunoassay method.

Collision-induced dissociation pathways of anabolic steroids by electrospray ionization tandem mass spectrometry

Anabolic steroids are structurally similar compounds, and their product-ion spectra obtained by tandem mass spectrometry under electrospray ionization conditions are quite difficult to interpret because of poly-ring structures and lack of a charge-retaining center in their chemical structures. In the present study, the fragmentation of nine anabolic steroids of interest to the racing industry was investigated by using triple quadrupole mass spectrometer, Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer, and a linear ion trap instrument. With the aid of an expert system software (Mass Frontier version 3.0), accurate mass measurements, and multiple stage tandem mass spectrometric (MS(n)) experiments, fragmentation pathways were elucidated for boldenone, methandrostenolone, tetrahydrogestrinone (THG), trenbolone, normethandrolone and mibolerone. Small differences in the chemical structures of the steroids, such as an additional double-bond or a methyl group, result in significantly different fragmentation pathways. The fragmentation pathways proposed in this paper allow interpretation of major product ions of other anabolic steroids reported by other researchers in a recent publication. The proposed fragmentation pathways are helpful for characterization of new steroids. The approach used in this study for elucidation of the fragmentation pathways is helpful in interpretation of complicated product-ion spectra of other compounds, drugs and their metabolites.

Detection, quantification and confirmation of anabolic steroids in equine plasma by liquid chromatography and tandem mass spectrometry

Anabolic androgenic steroids are related to the male sex hormones and are abused in equine sports. In an effort to deter the abuse of anabolic steroids, a sensitive LC-MS/MS method was developed for detection, quantification and confirmation of eight major anabolic steroids (testosterone, normethandrolone, nandrolone, boldenone, methandrostenolone, tetrahydrogestrinone (THG), trenbolone, and stanozolol) in equine plasma. Formation of solvent adduct ions of the analytes was observed under electrospray ionization (ESI) conditions, and desolvation of the solvent adduct ions by source collision-induced decomposition (CID) increased the abundance of the [M+H]+ ions as well as the multiple-reaction monitoring (MRM) signals. ESI (+) and APCI (+) were compared with respect to sensitivity for the analytes and the former provided better sensitivity. The matrix effect on ion suppression or enhancement was evaluated, and was negligible. Confirmation of the analytes was performed using criteria of three ion transitions and LC retention time of each analyte. The limit of detection (LOD) and quantification (LOQ) was 25 pg/mL. The limit of confirmation (LOC) was 25 pg/mL for boldenone; 50 pg/mL for normethandrolone, nandrolone, and methandrostenolone; and 100 pg/mL for testosterone, THG, trenbolone, and stanozolol. The analytes were evaluated for stability and found to be stable in plasma for 24h at room temperature, 13 days at 4 degrees C, and 34 days at -20 and -70 degrees C. The method was successfully applied to analyses of equine plasma samples for pharmacokinetics study. This method is sensitive and useful for detection, quantification and confirmation of these anabolic steroids in equine plasma.

Testosterone measurement by isotope-dilution liquid chromatography-tandem mass spectrometry: validation of a method for routine clinical practice

BACKGROUND

Immunoassay is unsatisfactory for measuring the testosterone concentrations typically found in women. Bench-top tandem mass spectrometers are a viable alternative technology for measurements in the clinical laboratory.

METHODS

We used stable-isotope dilution liquid chromatography-tandem mass spectrometry (ID/LC-MS/MS) to measure testosterone in plasma and serum. The sample volume was 50 muL in duplicate; preparation and analysis were carried out in a single tube, and a batch of 192 tubes was analyzed in 17.5 h.

RESULTS

Intra- and interassay imprecision was <15% in the range 0.3-49 nmol/L. Recovery of testosterone added to samples at concentrations of 0.625-20 nmol/L was 96% (CV = 12%; n = 26). Six samples were serially diluted with double charcoal-stripped serum to demonstrate linearity. Correlation (r(2)) with isotope-dilution gas chromatography-mass spectrometry for 20 pools of clinical samples (range, 0.5-38.5 nmol/L) was 0.99. Correlations with our extraction RIA were 0.97 for clinical samples from men (range, 8-46.3 nmol/L) and 0.66 for samples from women (range, 0.7-3.0 nmol/L), but were 0.35 for male samples containing <3 nmol/L testosterone and 0.77 for female samples containing >8 nmol/L. Various steroids added to double charcoal-stripped serum showed no interference at the retention time of the testosterone peak.

CONCLUSIONS

The ID/LC-MS/MS method has improved accuracy compared with immunoassay. The low sample volume and simplicity, rapidity, and robustness of the method make it suitable for use as a high-throughput assay in routine clinical biochemistry laboratories.

Low-fat high-fiber diet decreased serum and urine androgens in men

To validate our hypothesis that reduction in dietary fat may result in changes in androgen metabolism, 39 middle-aged, white, healthy men (50-60 yr of age) were studied while they were consuming their usual high-fat, low-fiber diet and after 8 wk modulation to an isocaloric low-fat, high-fiber diet. Mean body weight decreased by 1 kg, whereas total caloric intake, energy expenditure, and activity index were not changed. After diet modulation, mean serum testosterone (T) concentration fell (P < 0.0001), accompanied by small but significant decreases in serum free T (P = 0.0045), 5 alpha-dihydrotestosterone (P = 0.0053), and adrenal androgens (androstendione, P = 0.0135; dehydroepiandrosterone sulfate, P = 0.0011). Serum estradiol and SHBG showed smaller decreases. Parallel decreases in urinary excretion of some testicular and adrenal androgens were demonstrated. Metabolic clearance rates of T were not changed, and production rates for T showed a downward trend while on low-fat diet modulation. We conclude that reduction in dietary fat intake (and increase in fiber) results in 12% consistent lowering of circulating androgen levels without changing the clearance.

Application of pentafluorophenyl hydrazine derivatives to the analysis of nabumetone and testosterone in human plasma by liquid chromatography?atmospheric pressure chemical ionization?tandem mass spectrometry

Two carbonyl compounds, nabumetone and testosterone, were derivatized with pentafluorophenyl hydrazine (PFPH) and analyzed by atmospheric-pressure chemical-ionization mass spectrometry. The PFPH derivatives underwent dissociative electron capture in negative-ion APCI (ECAPCI) and gave intense [M-20](-) ions in the mass spectra. In positive-ion APCI, the PFPH derivatives underwent efficient protonation and gave intense [M + H](+) ions in the mass spectra. In CID, the major product ions of the [M-20](-) ions in ECAPCI corresponded to the partial moiety of PFPH. In contrast, the major product ions of [M + H](+) corresponded to the partial moiety of the analyte. By using selected reaction monitoring (SRM) detection, low pg of nabumetone (1 pg) and testosterone (7 pg) could be detected in both ECAPCI and positive-ion APCI. In comparison with the detection limits (SRM) of the underivatized analytes, use of the PFPH derivatives resulted in 2500-fold and 35-fold sensitivity enhancements for nabumetone and testosterone, respectively. The PFPH derivatives were applied to the analysis of nabumetone and testosterone in human plasma by both ECAPCI and positive-ion APCI and were found to enable detection of 0.1 ng mL(-1) nabumetone in spiked plasma. For testosterone, endogenous testosterone in female plasma was detected in both ECAPCI and positive-ion APCI.

Testosterone metabolic clearance and production rates determined by stable isotope dilution/tandem mass spectrometry in normal men: influence of ethnicity and age

The metabolic clearance rate (MCRT) and production rate (PRT) of testosterone (T) were measured using constant infusion of trideuterated (d3) T and quantitating serum d3T by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Serum unlabeled T (d0T) was measured by LC-MS-MS, and serum total T (d3T + d0T) was measured by RIA. Mean MCRR (measured by LC-MS-MS) in young white men (1272 +/- 168 liters/d) was not significantly different from young Asian men (1070 +/- 166 liters/d). Mean PRT was also not significantly different between the two ethnic groups (whites, 9.11 +/- 1.11 mg/d; Asians, 7.22 +/- 1.15 mg/d; P = 0.19 using d0T data). Both the mean MCRR (812 +/- 64 liters/d; P < 0.01) and the PRT (3.88 +/- 0.27 mg/d; P < 0.001) were significantly lower in middle-aged white men when compared with their younger counterparts. The mean MCRR and PRR calculated using serum total T or d0T data showed a diurnal variation, with levels at midday significantly higher than those measured in the evening in the young (MCRT, P < 0.01; PRT, P < 0.001) and to a lesser extent in the older men (MCRT, P < 0.05; PRT, P < 0.05 using total T and P < 0.001 using d0T data). We conclude that using LC-MS-MS to detect d3T in serum after constant infusion of stable isotope-labeled T allows the measurements of MCRT and PRT, which can be used to study androgen metabolism repeatedly after physiological or pharmacological interventions.