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      Multisteroid LC–MS/MS assay for glucocorticoids and androgens and its application in Addison's disease

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          Abstract

          Objective

          Liquid chromatography–tandem mass spectrometry (LC–MS/MS) offers superior analytical specificity compared with immunoassays, but it is not available in many regions and hospitals due to expensive instrumentation and tedious sample preparation. Thus, we developed an automated, high-throughput LC–MS/MS assay for simultaneous quantification of ten endogenous and synthetic steroids targeting diseases of the hypothalamic–pituitary–adrenal axis and gonads.

          Methods

          Deuterated internal standards were added to 85 μl serum and processed by liquid–liquid extraction. Cortisol, cortisone, prednisolone, prednisone, 11-deoxycortisol, dexamethasone, testosterone, androstenedione and progesterone were resolved by ultra-high-pressure chromatography on a reversed-phase column in 6.1 min and detected by triple-quadrupole mass spectrometry. The method was used to assess steroid profiles in women with Addison's disease (AD, n=156) and blood donors (BDs, n=102).

          Results

          Precisions ranged from 4.5 to 10.1% relative standard deviations (RSD), accuracies from 95 to 108% and extraction recoveries from 60 to 84%. The method was practically free of matrix effects and robust to individual differences in serum composition. Most postmenopausal AD women had extremely low androstenedione concentrations, below 0.14 nmol/l, and median testosterone concentrations of 0.15 nmol/l (interquartile range 0.00–0.41), considerably lower than those of postmenopausal BDs (1.28 nmol/l (0.96–1.64) and 0.65 nmol/l (0.56–1.10) respectively). AD women in fertile years had androstenedione concentrations of 1.18 nmol/l (0.71–1.76) and testosterone concentrations of 0.44 nmol/l (0.22–0.63), approximately half of those found in BDs of corresponding age.

          Conclusion

          This LC–MS/MS assay provides highly sensitive and specific assessments of glucocorticoids and androgens with low sample volumes and is suitable for endocrine laboratories and research. Its utility has been demonstrated in a large cohort of women with AD, and the data suggest that women with AD are particularly androgen deficient after menopause.

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          Most cited references35

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          Strategies for the assessment of matrix effect in quantitative bioanalytical methods based on HPLC-MS/MS.

          In recent years, high-performance liquid chromatography (HPLC) with tandem mass spectrometric (MS/MS) detection has been demonstrated to be a powerful technique for the quantitative determination of drugs and metabolites in biological fluids. However, the common and early perception that utilization of HPLC-MS/MS practically guarantees selectivity is being challenged by a number of reported examples of lack of selectivity due to ion suppression or enhancement caused by the sample matrix and interferences from metabolites. In light of these serious method liabilities, questions about how to develop and validate reliable HPLC-MS/MS methods, especially for supporting long-term human pharmacokinetic studies, are being raised. The central issue is what experiments, in addition to the validation data usually provided for the conventional bioanalytical methods, need to be conducted to confirm HPLC-MS/MS assay selectivity and reliability. The current regulatory requirements include the need for the assessment and elimination of the matrix effect in the bioanalytical methods, but the experimental procedures necessary to assess the matrix effect are not detailed. Practical, experimental approaches for studying, identifying, and eliminating the effect of matrix on the results of quantitative analyses by HPLC-MS/MS are described in this paper. Using as an example a set of validation experiments performed for one of our investigational new drug candidates, the concepts of the quantitative assessment of the "absolute" versus "relative" matrix effect are introduced. In addition, experiments for the determination of, the "true" recovery of analytes using HPLC-MS/MS are described eliminating the uncertainty about the effect of matrix on the determination of this commonly measured method parameter. Determination of the matrix effect allows the assessment of the reliability and selectivity of an existing HPLC-MS/MS method. If the results of these studies are not satisfactory, the parameters determined may provide a guide to what changes in the method need to be made to improve assay selectivity. In addition, a direct comparison of the extent of the matrix effect using two different interfaces (a heated nebulizer, HN, and ion spray, ISP) under otherwise the same sample preparation and chromatographic conditions was made. It was demonstrated that, for the investigational drug under study, the matrix effect was clearly observed when ISP interface was utilized but it was absent when the HN interface was employed.
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            Androgen production in women.

            To describe the sources, production rates, circulating concentrations, and regulatory mechanisms of the major androgen precursors and androgens in women. Review of the major published literature. Quantitatively, women secrete greater amounts of androgen than of estrogen. The major circulating steroids generally classified as androgens include dehydroepiandrosterone sulphate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (A), testosterone (T), and dihydrotestosterone in descending order of serum concentration, though only the latter two bind the androgen receptor. The other three steroids are better considered as pro-androgens. Dehydroepiandrosterone is primarily an adrenal product, regulated by adrenocorticotropic hormone (ACTH) and acting as a precursor for the peripheral synthesis of more potent androgens. Dehydroepiandrosterone is produced by both the ovary and adrenal, as well as being derived from circulating DHEAS. Androstenedione and testosterone are products of the ovary and the adrenal. Testosterone circulates both in its free form, and bound to protein including albumin and sex steroid hormone-binding globulin (SHBG), the levels of which are an important determinant of free testosterone concentration. The postmenopausal ovary is an androgen-secreting organ and the levels of testosterone are not directly influenced by the menopausal transition or the occurrence of menopause. Dihydrotestosterone (DHT) is primarily a peripheral product of testosterone metabolism. Severe androgen deficiency occurs in hypopituitarism, but other causes may lead to androgen deficiency, including Addison's disease, corticosteroid therapy, chronic illness, estrogen replacement (leads to elevated SHBG and, therefore, low free testosterone), premenopausal ovarian failure, or oophorectomy.
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              Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children.

              Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations. We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography-mass spectrometry (ID/GC-MS). Compared with ID/GC-MS, 7 of the 10 immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6-7.2 nmol/L, 3 of the 10 immunoassays gave positive mean differences >2.0 nmol/L (range, -0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2-58 nmol/L, 3 of the 10 immunoassays tested gave mean differences >4.0 nmol/L (range, -4.8 to 2.6 nmol/L). None of the immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.

                Author and article information

                Journal
                Endocr Connect
                Endocr Connect
                EC
                Endocrine Connections
                BioScientifica (Bristol )
                2049-3614
                04 July 2013
                01 September 2013
                : 2
                : 3
                : 125-136
                Affiliations
                [1 ]Department of Clinical Science University of Bergen N-5021, BergenNorway
                [2 ]The Hormone Laboratory Haukeland University Hospital N-5021, BergenNorway
                [3 ]Department of Medicine Haukeland University Hospital Bergen, N-5021Norway
                Author notes
                Correspondence should be addressed to P Methlie Email paal.methlie@ 123456med.uib.no
                Article
                EC130023
                10.1530/EC-13-0023
                3845685
                23825158
                a6e8d190-aef0-4b2c-ba98-f9f4f13c3b19
                © 2013 The Authors

                This work is licensed under a Creative Commons Attribution 3.0 Unported License

                History
                : 7 June 2013
                : 12 June 2013
                Categories
                Research

                liquid chromatography mass spectrometry,androgens,glucocorticoids,adrenal insufficiency,addison's disease

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