Dexamethasone suppression test: development of a method for simultaneous determination of cortisol and dexamethasone in human plasma by liquid chromatography/tandem mass spectrometry

Effect of autologous bone marrow derived mesenchymal stem cells in treatment of rheumatoid arthritis

INTRODUCTION

Chronic inflammation causes articular bone and cartilage degeneration in people with rheumatoid arthritis (RA). Despite recent advancements in the management of RA, adverse side effects and ineffective treatments remain a problem. Effective treatment is usually hampered by financial issues. As a result, less expensive medications that reduce both inflammation and bone resorption are required. Mesenchymal stem cells (MSCs) have recently been identified as a potential therapy for RA.

AIM OF THE STUDY

This study aimed to examine the anti-arthritic effect of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs), oligosaccharides (Os), and human placental extract (HPE), individually and combined, on an RA model, using Complete Freund's adjuvant (CFA)-induced arthritis in rats.

MATERIALS AND METHODS

In female rats, RA was induced by injecting CFA in the paw of the hind limb. Rat bone marrow-MSCs, oligosaccharides, and human placental extract (HPE) were given individually and in combination via the intraperitoneal route. A complete blood count (CBC), erythrocyte sedimentation rate (ESR), serum cortisol, urea, uric acid, and other biochemical parameters were measured to determine the safety and efficacy of the different treatments. Histopathological analysis of bone sections was carried out.

RESULTS

Combining oligosaccharides and HPE therapy with the infusion of rat-bone marrow MSCs had beneficial antiarthritic and anti-inflammatory effects in CFA-induced arthritis in rats: overall such triple therapy significantly reduced serum levels of IL-6, IL-10, and TNF-alpha in comparison with all other combinations (all P > 0.05). Meanwhile, the triple therapy did not have negative effects on levels of CBC, serum cortisol, ESR, and liver enzymes (all NS) as well as on renal functions (NS). Also, the histopathological analysis showed significant improvements in the healing and remodelling of osteoporotic lesions in arthritic rats. As shown by counting apoptotic cells as a histopathological substitute for measuring apoptotic or regeneration markers, the lowest count was found in the group treated with a triple therapy of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs), oligosaccharides, and HPE.

CONCLUSION

The combination of rat MSCs, oligosaccharides, and HPE has the potential to be an effective treatment for rheumatoid arthritis.

Sensitive and rapid quantitation of dexamethasone in human plasma using liquid chromatography coupled with triple quadrupole mass spectrometer

The aim of this paper was to develop, validate, and utilize a sensitive liquid chromatography-tandem mass spectrometry bioanalytical method for bioequivalence/clinical trial studies conducted in human plasma. To accomplish the target, a stable labeled internal standard, that is, dexamethasone D4 was used as an internal standard to track and compensate the parent compound during processing, and extraction from plasma. The method involves a rapid liquid-liquid phase extraction from plasma, followed by reverse phase chromatography, and mass spectrometry detection, with a total run time of 3.5 min. The method was developed and validated from 2 to 600 ng/ml for dexamethasone. The mean recovery for dexamethasone was found to be 81.0%. The validated method enabled the analysis of dexamethasone in samples from clinical pharmacokinetic studies. The peak concentration of dexamethasone ranged between 253 to 281 ng/ml and 319 to 343 ng/ml, respectively, in fasted and fed conditions. The terminal half-life values for dexamethasone ranged between 3.5 to 8.2 h and 3.0 to 7.5 h, respectively.

Cortisol: Analytical and clinical determinants

Cortisol, the main human glucocorticoid, is synthesized from cholesterol in the adrenal cortex and predominantly metabolized by the liver. Interpretation of quantitative results from the analysis of serum, urine and saliva is complicated by variation in circadian rhythm, response to stress as well as the presence of protein-bound and free forms. Interestingly, cortisol is the only hormone routinely measured in serum, urine, and saliva. Preanalytical and analytical challenges arise in each matrix and are further compounded by the use of various stimulation and suppression tests commonly employed in clinical practice. Although not yet included in clinical guidelines, measurement of cortisol in hair may be of interest in specific situations. Immunoassays are the most widely used methods in clinical laboratories to measure cortisol, but they are susceptible to interference from synthetic and endogenous steroids, generally producing a variable overestimation of true cortisol results, especially in urine. Analysis by mass spectrometry provides higher specificity and allows simultaneous measurement of multiple steroids including synthetic steroids, thus reducing diagnostic uncertainty. An integrated review of cortisol in various disease states is also addressed.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) on diagnosis of Cushing's syndrome

Cushing's syndrome is defined by prolonged exposure to glucocorticoids, leading to excess morbidity and mortality. Diagnosis of this rare pathology is difficult due to the low specificity of the clinical signs, the variable severity of the clinical presentation, and the difficulties of interpretation associated with the diagnostic methods. The present consensus paper by 38 experts of the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology aimed firstly to detail the circumstances suggesting diagnosis and the biologic diagnosis tools and their interpretation for positive diagnosis and for etiologic diagnosis according to ACTH-independent and -dependent mechanisms. Secondly, situations making diagnosis complex (pregnancy, intense hypercortisolism, fluctuating Cushing's syndrome, pediatric forms and genetically determined forms) were detailed. Lastly, methods of surveillance and diagnosis of recurrence were dealt with in the final section.

A multidisciplinary approach to the management of adrenal incidentaloma

An adrenal incidentaloma (AI) is an adrenal neoplasm incidentally discovered during an imaging unrelated to suspected adrenal disease. The aim of the present review is to offer practical guidance on the multidisciplinary approach of AIs.Areas covered:The prevalence of AI is high in the aging population (up to 5-8%); however, hormonally active or malignant conditions are rare. After the discovery of an AI, it is suggested to assess in parallel if the mass is potentially malignant and functionally active. The answer to the former question is mainly based on medical history (extra-adrenal malignancies, new-onset of signs or symptoms) and imaging (conventional radiology and/or nuclear medicine). The answer to the latter question is a complete endocrine evaluation of both cortical (glucocorticoids, mineralocorticoids) and medullary (catecholamines) secretion.Expert opinion:A multidisciplinary discussion is suggested for patients with adrenal disease, after the exclusion of nonfunctioning benign cortical adenoma, in order to plan a close and tailored follow-up for the suspected malignant or functioning forms. Surgery is advised for patients with malignant disease (adrenocortical cancer) or with clinically relevant secreting neoplasm (primary aldosteronism, Cushing's syndrome, and pheochromocytoma).

Method-Specific Cortisol and Dexamethasone Thresholds Increase Clinical Specificity of the Dexamethasone Suppression Test for Cushing Syndrome

BACKGROUND

The dexamethasone suppression test (DST) is the recommended first-tier test for suspected Cushing syndrome (CS). Missed dexamethasone intake or insufficient dexamethasone serum exposure may yield false positive results. Quantification of serum dexamethasone in DST samples may therefore improve test performance.

METHODS

Simultaneous quantification of dexamethasone and cortisol by liquid chromatography-tandem mass spectrometry in 400 DST serum samples (100 overt CS, 200 excluded CS, 100 adrenal incidentalomas with (possible) autonomous cortisol secretion, AI-ACS) randomly selected within the indication groups. The 2.5th percentile of dexamethasone in patients with excluded CS was considered the lower limit of normal (LLN).

RESULTS

Serum dexamethasone varied from undetectable to 20.2 ng/mL with a median of 4.8 ng/mL (95% CI 4.5-5.1 ng/mL). Dexamethasone was undetectable in only 16 patients (4%), suggesting non-compliance. The dexamethasone LLN was 1.8 ng/mL (4.6 nmol/L). Decreased glomerular filtration rate and diabetes mellitus were associated with higher serum dexamethasone concentration, while body mass index, sex, age, nicotine, and oral contraceptives had no significant effect. By excluding the 27 samples with dexamethasone <LLN and applying the method-specific cortisol cutoff of 2.4 µg/dL (66 nmol/L) to samples with suspected CS, the clinical specificity for CS increased from 67.5% to 92.4% while preserving 100% clinical sensitivity. Among 100 AI-ACS samples (defined by immunoassay), 4 samples had dexamethasone <1.8 ng/mL and 14 samples had cortisol <2.4 µg/dL, which excluded autonomous cortisol secretion.

CONCLUSIONS

Quantification of dexamethasone and method-specific cortisol cutoffs in DST samples may reduce the false positive rate and lower the proportion of patients requiring further workup.

Development and validation of a combined liquid chromatography tandem-mass spectrometry assay for the quantification of aprepitant and dexamethasone in human plasma to support pharmacokinetic studies in pediatric patients

A pharmacokinetic study was set up to investigate the pharmacokinetics of the anti-emetic agents aprepitant and dexamethasone and the drug-drug interaction between these drugs in children. In order to quantify aprepitant and dexamethasone, a liquid chromatography-tandem mass spectrometry assay was developed and validated for the simultaneous analysis of aprepitant and dexamethasone. Protein precipitation with acetonitrile-methanol (1:1, v/v) was used to extract the analytes from plasma. The assay was based on reversed-phase chromatography coupled with tandem mass spectrometry detection operating in the positive ion mode. The assay was validated based on the guidelines on bioanalytical methods by the US Food and Drug Administration and European Medicines Agency. The calibration model was linear and a weighting factor of 1/concentration² was used over the range of 0.1-50 ng/mL for aprepitant and 1-500 ng/mL for dexamethasone. Intra-assay and inter-assay bias were within ±20% for all analytes at the lower limit of quantification and within ±15% at remaining concentrations. Dilution integrity tests showed that samples exceeding the upper limit of quantification can be diluted 100 times in control matrix. Stability experiments showed that the compounds are stable in the biomatrix for 25 h at room temperatures and 89 days at -20 °C. This assay is considered suitable for pharmacokinetic studies and will be used to study the drug-drug interaction between aprepitant and dexamethasone in pediatric patients.

Cortisol Measurements in Cushing's Syndrome: Immunoassay or Mass Spectrometry?

Determination of cortisol levels in the urine (24 hours urine free cortisol), saliva (late-night), or serum (total cortisol after dexamethasone suppression) is recommended to screen for Cushing's syndrome (CS). This review focuses on the differences between the frequently used cortisol-antibody immunoassay-based methods and the highly specific mass-spectrometry-based methods that are progressively being employed in clinical laboratories for CS screening. The particular characteristics of cortisol metabolism and the lack of specificity of the immunoassays cause marked differences between both methods that are in turn highly dependent on the biological matrix, in which the cortisol is measured. Understanding the origin of these differences is essential for the interpretation of these results. Although cross-reactivity with endogenous steroids leads to grossly inaccurate results of immunoassay measurements of cortisol in the saliva and urine, preliminary evidence suggests that the clinical sensitivity of CS screening using immunoassays may be similar to CS screening using mass spectrometry. However, mass spectrometry offers more accurate results and considerably reduced variation across laboratories, while avoiding false-positive results. Moreover, mass spectrometry can overcome some common diagnostic challenges, such as identification of exogenous corticosteroids or simultaneous assessment of appropriate dexamethasone levels in suppression tests. Further, comprehensive mass spectrometry-based profiling of several steroid metabolites may be useful for discriminating among different subtypes of CS. Finally, this review discusses the main preanalytical factors that could cause variations in cortisol measurements and their influence on the reliability of the results.

Retrospective analysis of repeated dexamethasone suppression tests – the added value of measuring dexamethasone

Background

In the evaluation for hypercortisolism (Cushing’s syndrome), the 1 mg overnight dexamethasone suppression test has an important role, but false-positive results can occur due to low serum dexamethasone. Given the high intraindividual reproducibility of post-dexamethasone suppression test serum cortisol concentrations, we investigated the chance of success of repeating a non-suppressed dexamethasone suppression test if serum dexamethasone is low.

Methods

We retrospectively analysed the results of 1901 consecutive dexamethasone suppression tests performed in our laboratory from February 2011 to November 2018. Serum dexamethasone and cortisol were measured by LC-MS/MS, and both were reported. The 2.5 and 5th percentiles of serum dexamethasone in suppressed dexamethasone suppression tests were investigated as cut-off value. Then, we retrospectively determined the success rate of repeating an initial, non-suppressed dexamethasone suppression test in 131 patients, stratified by initial serum dexamethasone.

Results

At serum dexamethasone concentrations between the 2.5 and 5th percentiles (3.2–3.9 nmol/L), significantly more non-suppressed dexamethasone suppression tests were observed (27/67) than in the control group of 1357 tests having serum dexamethasone ⩾6 nmol/L (40% vs. 30%, P = 0.047), indicating that 3.9 nmol/L is the better cut-off. Overall, 40% of non-suppressed dexamethasone suppression tests were repeated, but repeat testing was performed more often when serum dexamethasone was low. In patients who had initial serum dexamethasone below the cut-off of 3.9 nmol/L, a significantly higher chance of having a suppressed repeat dexamethasone suppression test was observed compared to the control group: 57% (31/54) vs. 26% (15/57), P = 0.001.

Conclusions

Measuring and reporting serum dexamethasone in dexamethasone suppression tests have added value for the selection of patients who might benefit from a repeat dexamethasone suppression test. We suggest a cut-off for serum dexamethasone of ⩾3.9 nmol/L.

Autonomous cortisol secretion in adrenal incidentalomas

Adrenal incidentalomas (AI) are one of the most frequent reasons for consultation in Endocrinology, as they are present in 3-10% of the general population. Up to 20% of them may have autonomous cortisol secretion (ACS), a term that refers to AI carriers with biochemical evidence of excess cortisol, but without the "specific" clinical signs of Cushing's syndrome. As ACS is associated with an increased risk of diabetes, obesity, high blood pressure (HBP), osteoporosis, cardiovascular events, and global mortality; its correct identification is of great importance. There are different laboratory assays to detect ACS, but all of them have some limitations. The dexamethasone suppression test is the most accepted for screening. However, there is no consensus on the cutoff point that should be used. Low levels of ACTH and DHEA-S and high urinary free cortisol are also associated with ACS, but in isolation they are of little value to establish the diagnosis. Considering its clinical implications and the lack of consensus in the diagnosis and in which is the most appropriate management of these patients, this review offers a quick reference guide of ACS, presenting an exhaustive review of the topic: its definition, epidemiology, diagnosis, clinical implications, treatment, and follow-up.

Development of a rapid liquid chromatography tandem mass spectrometry method for the quantitation of serum dexamethasone and its clinical verification

Background Measurement of serum dexamethasone during the overnight dexamethasone-suppression test has been recommended to reduce false-positive results when investigating Cushing's syndrome or increasingly commonly found adrenal incidentalomas. Despite this, there remains a paucity of well-validated dexamethasone methods currently available. Here, we describe the development of a rapid and sensitive liquid chromatography tandem mass spectrometry serum dexamethasone assay and verify its utility in a cohort of postmenopausal females. Method Isotopically labelled internal standard was added to samples prior to supported liquid extraction. Extracts were analysed using liquid chromatography tandem mass spectrometry in the positive electrospray ionization mode. Multiple reaction monitoring was used to detect dexamethasone and its corresponding internal standard transitions. Normal healthy postmenopausal women ( n = 95) were recruited and underwent an overnight dexamethasone suppression test, with serum dexamethasone and cortisol measurements at 09:00 after administration of oral dexamethasone 1 mg at 23:00 the night before. Results Mean intra- and inter-assay imprecision were 4.1% and 2.9%, respectively, for dexamethasone concentrations of 1.5, 6.0 and 12.0 nmol/L. Matrix effects were found to be negligible at 106-109% with recovery ranging from 96 to 100%. The limit of quantitation was 0.25 nmol/L, and structural analogue analysis proved the method to be robust against interferences. Applying a serum dexamethasone cut-off of >3.3 nmol/L was associated with a serum cortisol ≤50 nmol/L in 84/95 individuals. Conclusion We have developed a sensitive and robust liquid chromatography tandem mass spectrometry method for the quantitation of serum dexamethasone. The method can be used to identify false-positive results during the overnight dexamethasone suppression test or for pharmacokinetic studies.

Cushing's Syndrome and Hypothalamic-Pituitary-Adrenal Axis Hyperactivity in Chronic Central Serous Chorioretinopathy

OBJECTIVE

Central serous chorioretinopathy (CSC), a specific form of macular degeneration, has been reported as presenting manifestation of Cushing's syndrome. Furthermore, CSC has been associated with both exogenous hypercortisolism and endogenous Cushing's syndrome. It is important to know whether CSC patients should be screened for Cushing's syndrome. Although hypothalamic-pituitary-adrenal (HPA) axis hyperactivity in CSC has been suggested, no detailed evaluation of the HPA axis has been performed in a large cohort of CSC patients. This study aimed to investigate whether Cushing's syndrome prevalence is increased among chronic CSC (cCSC) patients and whether detailed endocrinological phenotyping indicates hyperactivity of the HPA axis.

DESIGN

Cross-sectional study.

PATIENTS

86 cCSC patients and 24 controls.

MEASUREMENTS

Prevalence of Cushing's syndrome, HPA axis activity.

RESULTS

None of the cCSC patients met the clinical or biochemical criteria of Cushing's syndrome. However, compared to controls, HPA axis activity was increased in cCSC patients, reflected by higher 24 h urinary free cortisol, and accompanying higher waist circumference and diastolic blood pressure, whereas circadian cortisol rhythm and feedback were not different. Chronic CSC patients did not report more stress or stress-related problems on questionnaires.

CONCLUSION

No case of Cushing's syndrome was revealed in a large cohort of cCSC patients. Therefore, we advise against screening for Cushing's syndrome in CSC patients, unless additional clinical features are present. However, our results indicate that cCSC is associated with hyperactivity of the HPA axis, albeit not accompanied with perception of more psychosocial stress.

In the overnight dexamethasone suppression test, 1.0 mg loading is superior to 0.5 mg loading for diagnosing subclinical adrenal Cushing's syndrome based on plasma dexamethasone levels determined using liquid chromatography-tandem mass spectrometry

The low-dose dexamethasone suppression test (DST) is one of the commonly used initial tests for endogenous Cushing's syndrome (CS). However, there are two loading dose regimens (0.5-mg and 1-mg), which may cause some confusion in daily practice in Japan; furthermore, there are no reports regarding whether 0.5-mg DST is a better loading dose for detecting adrenal subclinical CS (SCS) based on the plasma dexamethasone (DEX) levels. Therefore, the aims of this study were (a) to develop a novel assay to measure DEX by using liquid chromatography tandem-mass spectrometry (LC-MS/MS) and (b) to compare between the 0.5-mg and 1-mg DST for SCS diagnosis based on the DEX levels. The study retrospectively analyzed 52 consecutive subjects hospitalized for diagnosis of adrenal incidentaloma but who did not exhibit an overt CS phenotype; eight (15.4%) patients were affected with adrenal SCS. Inter-individual variability of DEX levels after the DST was high, but intra-individual variability was low. DEX levels after 1-mg loading in each patient was around two times higher than those after 0.5-mg loading (ρ = 0.853 and p < 0.001). There were 45 (86.5%) and 17 (32.7%) subjects with DEX levels ≤2.2 ng/mL after the 0.5-mg and 1-mg DST, respectively (p < 0.001). Twenty-eight (93.3%) of 30 subjects and four (21.1%) of 19 subjects with detectable ACTH levels after the 0.5-mg and 1.0-mg DST, respectively, did not exhibit DEX levels >2.2 ng/mL. These results clearly indicate that the 1-mg DST is superior to 0.5-mg loading for the diagnosis of adrenal SCS.

Steroid metabolome analysis reveals prevalent glucocorticoid excess in primary aldosteronism

BACKGROUND

Adrenal aldosterone excess is the most common cause of secondary hypertension and is associated with increased cardiovascular morbidity. However, adverse metabolic risk in primary aldosteronism extends beyond hypertension, with increased rates of insulin resistance, type 2 diabetes, and osteoporosis, which cannot be easily explained by aldosterone excess.

METHODS

We performed mass spectrometry-based analysis of a 24-hour urine steroid metabolome in 174 newly diagnosed patients with primary aldosteronism (103 unilateral adenomas, 71 bilateral adrenal hyperplasias) in comparison to 162 healthy controls, 56 patients with endocrine inactive adrenal adenoma, 104 patients with mild subclinical, and 47 with clinically overt adrenal cortisol excess. We also analyzed the expression of cortisol-producing CYP11B1 and aldosterone-producing CYP11B2 enzymes in adenoma tissue from 57 patients with aldosterone-producing adenoma, employing immunohistochemistry with digital image analysis.

RESULTS

Primary aldosteronism patients had significantly increased cortisol and total glucocorticoid metabolite excretion (all P < 0.001), only exceeded by glucocorticoid output in patients with clinically overt adrenal Cushing syndrome. Several surrogate parameters of metabolic risk correlated significantly with glucocorticoid but not mineralocorticoid output. Intratumoral CYP11B1 expression was significantly associated with the corresponding in vivo glucocorticoid excretion. Unilateral adrenalectomy resolved both mineralocorticoid and glucocorticoid excess. Postoperative evidence of adrenal insufficiency was found in 13 (29%) of 45 consecutively tested patients.

CONCLUSION

Our data indicate that glucocorticoid cosecretion is frequently found in primary aldosteronism and contributes to associated metabolic risk. Mineralocorticoid receptor antagonist therapy alone may not be sufficient to counteract adverse metabolic risk in medically treated patients with primary aldosteronism.

FUNDING

Medical Research Council UK, Wellcome Trust, European Commission.

The relationship between 63days of 24-h urinary free cortisol and hair cortisol levels in 10 healthy individuals

BACKGROUND

Interest in measuring cortisol in scalp hair is increasing because of its assumed ability to provide a historical timeline of previous systemic levels of cortisol. Yet, it remains uncertain how well hair cortisol represents the total systemic secretion of cortisol over time.

METHODS

Ten healthy individuals collected 24-h urine samples for 63 consecutive days and provided a hair sample at the end of the study period. 24-h urinary creatinine levels in every urine sample were determined to assess completeness of the samples. Cortisol levels in 24-h urine samples and in hair were measured with liquid chromatography tandem mass spectrometry. The correlations between urinary cortisol and hair cortisol were calculated using Kendall's tau.

RESULTS

We found a nonsignificant moderate correlation between average urinary cortisol secretion and average hair cortisol concentration r_т=0.422, p=0.089.

CONCLUSIONS

Hair cortisol concentration correlates low to moderately with 24-h urinary cortisol concentration over a period of 63days.

Endogenous glucocorticoid analysis by liquid chromatography-tandem mass spectrometry in routine clinical laboratories

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical technique that offers exceptional selectivity and sensitivity. Used optimally, LC-MS/MS provides accurate and precise results for a wide range of analytes at concentrations that are difficult to quantitate with other methodologies. Its implementation into routine clinical biochemistry laboratories has revolutionised our ability to analyse small molecules such as glucocorticoids. Whereas immunoassays can suffer from matrix effects and cross-reactivity due to interactions with structural analogues, the selectivity offered by LC-MS/MS has largely overcome these limitations. As many clinical guidelines are now beginning to acknowledge the importance of the methodology used to provide results, the advantages associated with LC-MS/MS are gaining wider recognition. With their integral role in both the diagnosis and management of hypo- and hyperadrenal disorders, coupled with their widespread pharmacological use, the accurate measurement of glucocorticoids is fundamental to effective patient care. Here, we provide an up-to-date review of the LC-MS/MS techniques used to successfully measure endogenous glucocorticoids, particular reference is made to serum, urine and salivary cortisol.

Pros and cons of the tuberculosis drugome approach--an empirical analysis

Drug-resistant Mycobacterium tuberculosis (MTB), the causative pathogen of tuberculosis (TB), has become a serious threat to global public health. Yet the development of novel drugs against MTB has been lagging. One potentially powerful approach to drug development is computation-aided repositioning of current drugs. However, the effectiveness of this approach has rarely been examined. Here we select the "TB drugome" approach--a protein structure-based method for drug repositioning for tuberculosis treatment--to (1) experimentally validate the efficacy of the identified drug candidates for inhibiting MTB growth, and (2) computationally examine how consistently drug candidates are prioritized, considering changes in input data. Twenty three drugs in the TB drugome were tested. Of them, only two drugs (tamoxifen and 4-hydroxytamoxifen) effectively suppressed MTB growth at relatively high concentrations. Both drugs significantly enhanced the inhibitory effects of three first-line anti-TB drugs (rifampin, isoniazid, and ethambutol). However, tamoxifen is not a top-listed drug in the TB drugome, and 4-hydroxytamoxifen is not approved for use in humans. Computational re-examination of the TB drugome indicated that the rankings were subject to technical and data-related biases. Thus, although our results support the effectiveness of the TB drugome approach for identifying drugs that can potentially be repositioned for stand-alone applications or for combination treatments for TB, the approach requires further refinements via incorporation of additional biological information. Our findings can also be extended to other structure-based drug repositioning methods.

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

OBJECTIVE

Liquid chromatography-mass spectrometry (LC-MS/MS) offers superior analytical specificity compared to immunoassays, but is not available in many regions and hospital due to expensive instrumentation and tedious sample preparation. Thus, we developed an automated, high-throughput LC-MS/MS assay for simultaneous quantification of 10 endogenous and synthetic steroids targeting diseases of the hypothalamo-pituitary-adrenal-axis and gonads.

METHODS

Deuterated internal standards were added to 85µl 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 minutes, and detected by triple-quadrupole MS. The method was used to assess steroid profiles in women with Addison's disease (AD, n=156) and blood donors (BD, n=102).

RESULTS

Precisions ranged 4.5-10.1% RSD, accuracies 95-108%, and extraction recoveries 60-84%. The method was practically free of matrix effects and robust to individual differences in serum composition. Most postmenopausal AD women had extremely low androstenedione below 0.14 nmol/L and median testosterone 0.15 nmol/L [interquartile range 0.00-0.41], considerably lower than postmenopausal BD (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 1.18 nmol/L [0.71-1.76] and testosterone 0.44 nmol/L [0.22-0.63], approximately half of levels found in BD 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 was demonstrated in a large cohort of women with AD, and the data suggest that women with AD are particularly androgen deficient after menopause.

The use of mass spectrometry to improve the diagnosis and the management of the HPA axis

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is becoming a standard analytical tool in the clinical laboratory for the measurement of small molecules, including steroid hormones. Endocrinologists are coming to acknowledge the superior quality of measurement that is achievable by LC-MS/MS through the enhanced analytical specificity and high sensitivity that this technique offers over conventional immunoassay (IA) methodologies. Additionally, LC-MS/MS overcomes many of the problems encountered in immunoassays, such as anti-reagent antibody interferences and cross-reactivity with structurally related compounds. The potential benefits of applying LC-MS/MS for the assessment of the hypothalamic-pituitary-adrenal (HPA) axis are beginning to be realised. This review critically evaluates recent developments in the application of LC-MS/MS for measurement of glucocorticoids and mineralocorticoids towards the diagnosis and management of HPA axis disorders and aims to address the current unmet need in this expanding field of endocrinology for which future studies into the potential applications of LC-MS/MS should be directed.