Simultaneous Quantification of Serum Symmetric Dimethylarginine, Asymmetric Dimethylarginine and Creatinine for Use in a Routine Clinical Laboratory.

Background Symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA) are naturally occurring amino acids classed as uremic toxins by the EUTOX working group. SDMA is principally excreted through the kidneys and is a well-known renal function marker, ADMA is a potent inhibitor of nitric oxide production. Here, we describe the development of a rapid and sensitive liquid chromatography tandem mass spectrometry method for simultaneous measurement of SDMA, ADMA and creatinine. Method Serum samples were prepared by protein precipitation and dilution with acetonitrile prior to injection onto a Waters TQS-Micro. Multiple reaction monitoring was used to detect SDMA, ADMA, creatinine, and their corresponding internal standard transitions after separation with a HILIC analytical column. Sample stability and intra-individual variation studies were also assessed following ethical approval. Results The retention time for creatinine was 0.43, SDMA 1.10 and ADMA 1.14 minutes. Mean recovery for creatinine was 103%, SDMA was 100% and ADMA was 103%, matrix effects were minimal (<6%). Lower limit of quantitation for creatinine and SDMA/ADMA was 17.5 µmol/L and 0.1 µmol/L respectively. Analytical imprecision showed a coefficient of variation <10% for all analytes across the working range of the assays. Intra-individual variation for creatinine was 4.7%, SDMA 7.5% and ADMA 7.6%. Discussion We have developed a rapid assay for LC-MS/MS measurement of SDMA, ADMA and creatinine in a routine clinical laboratory. It is simple, reproducible, and easy to perform. The stability of SDMA and ADMA pre- and post-centrifugation allows for their routine use without any special sample handling requirements.

Investigation into the linearity of the Roche c 702 carbamazepine assay.

BACKGROUND: Carbamazepine is an anticonvulsant drug which is monitored in patients due to toxic side effects. At Manchester University NHS Foundation Trust (MFT), carbamazepine is measured using Roche's Kinetic Interaction of Microparticles in Solution (KIMS) method on the c 702 platform. The assay has an upper limit of linearity of 20 mg/L. Samples with concentrations above this limit should be identified and manually diluted. However, a poor EQA return from UK NEQAS for Tox and TDM Distribution 456 has highlighted an issue with the Roche KIMS assay. Sample A of the distribution had a carbamazepine concentration of 36 mg/L but was underreported by several Roche users. This indicated that the assay was not consistently identifying high concentration samples which required a dilution. METHOD: In this investigation, fresh frozen plasma was spiked with carbamazepine concentrations ranging from 15 to 40 mg/L. The spiked samples and EQA material were analysed at two clinical laboratories using the Roche KIMS assay. RESULTS: Samples spiked with concentrations 20-30 mg/L were not consistently identified for dilution by the analyser. This was observed at both hospital sites. Spike samples and EQA with concentrations >30 mg/L were correctly identified at both sites. CONCLUSION: The manual dilution policy has been changed at MFT, so all samples with a carbamazepine level ≥15 mg/L will be manually diluted. The problem was reported to Roche who are investigating the issue further. We would suggest that other laboratories look at validating their dilution protocols.

Evaluating the diagnostic accuracy of androgen measurement in polycystic ovary syndrome: a systematic review and diagnostic meta-analysis to inform evidence-based guidelines.

BACKGROUND: Biochemical hyperandrogenism is a hallmark and diagnostic feature of polycystic ovary syndrome (PCOS). However, the most accurate androgen measurement for assessing biochemical hyperandrogenism in PCOS diagnosis remains uncertain. OBJECTIVE AND RATIONALE: This systematic review aimed to assess different androgen measures [including total testosterone (TT), calculated free testosterone (cFT), free androgen index (FAI), androstenedione (A4), dehydroepiandrosterone sulfate (DHEAS), and dihydrotestosterone (DHT)] for accuracy in diagnosing biochemical hyperandrogenism in women with PCOS, to inform the 2023 International PCOS Evidence-based Guidelines. SEARCH METHODS: To update evidence from the 2018 International PCOS Guidelines, a systematic search from 3 July 2017 to 23 June 2023 was conducted across Medline (Ovid), CINAHL, all EBM, EMBASE, and PsycInfo for articles evaluating androgens in the diagnosis of biochemical hyperandrogenism. The revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the risk of bias and applicability. A diagnostic test accuracy meta-analysis was performed using STATA 18 software. Summary sensitivity and specificity were calculated with 95% CIs using the bivariate model, while the hierarchical summary receiver operating characteristics (ROC) model was used to produce a summary ROC curve. OUTCOMES: Of 23 studies reviewed, 18 were included in the meta-analysis, with data from 2857 participants (1650 with PCOS and 1207 controls). For diagnosing biochemical hyperandrogenism in PCOS, the pooled sensitivity, specificity, and AUC with 95% CI were for TT: 0.74 (0.63-0.82), 0.86 (0.77-0.91), and 0.87 (0.84-0.90); cFT: 0.89 (0.69-0.96), 0.83 (0.79-0.86), and 0.85 (0.81-0.88); FAI: 0.78 (0.70-0.83), 0.85 (0.76-0.90), and 0.87 (0.84-0.90); A4: 0.75 (0.60-0.86), 0.71 (0.51-0.85), and 0.80 (0.76-0.83); and DHEAS: 0.75 (0.61-0.85), 0.67 (0.48-0.81), and 0.77 (0.73-0.81), respectively. In subgroup analyses, liquid chromatography with tandem mass spectrometry (LC-MS/MS) had superior sensitivity for measuring cFT, FAI, A4, and DHEAS, and superior specificity for measuring TT, cFT, and FAI, compared to the direct immunoassay method. WIDER IMPLICATIONS: Our results directly informed the 2023 International PCOS Guideline recommendations to use TT and FT as the first-line laboratory tests to assess biochemical hyperandrogenism in the diagnosis of PCOS. cFT should be assessed by equilibrium dialysis or ammonium sulfate precipitation, or calculated using FAI. If TT or cFT are not elevated, A4 and DHEAS could also be considered, noting their poorer specificity. Laboratories should utilize LC-MS/MS for androgen measurement given its high accuracy. Future studies should focus on establishing optimal normative cut-off values in large, unselected, and ethnically diverse cohorts of women. REGISTRATION NUMBER: The review protocol was prepublished in the 2023 PCOS Guideline Technical Report (https://www.monash.edu/__data/assets/pdf_file/0010/3379591/TechnicalReport-2023.pdf).

Development and validation of a novel 7α-hydroxy-4-cholesten-3-one (C4) liquid chromatography tandem mass spectrometry method and its utility to assess pre-analytical stability.

OBJECTIVES: 7α-Hydroxy-4-cholesten-3-one (C4) is the common intermediary of both primary bile acids. C4 is recommended by the British Society of Gastroenterology for the investigation of bile acid diarrhoea (BAD) in patients with chronic diarrhoea. This project aimed to develop and validate an assay to quantitate C4 in serum and assess the stability of C4 in unseparated blood. METHODS: Accuracy was underpinned by calibrating to quantitative nuclear magnetic resonance analysis. C4 was analysed in a 96-well plate format with a deuterated C4 internal standard and liquid-liquid extraction. Validation followed the 2018 Food and Drug Administration guidelines. To assess C4 stability, healthy volunteers (n=12) donated 8 fasted samples each. Samples were incubated at 20 °C for up to 72 h and retrieved, centrifuged, aliquoted and frozen for storage at different time points prior to C4 analysis. RESULTS: The C4 method demonstrated excellent analytical performance and passed all validation criteria. The method was found to be accurate, precise, free from matrix effects and interference. After 72 h of delayed sample separation, C4 concentration gradually declined by up to 14 % from baseline. However, the change was not significant for up to 12 h. CONCLUSIONS: We present a robust method of analysing serum C4, offering a convenient alternative to 75SeHCAT for BAD investigation. C4 was found to decline in unseparated blood over time; however, after 12 h the mean change was <5 % from baseline. Our results suggest C4 is suitable for collection from both primary and secondary care prior to gastroenterology referral.

Discriminatory Value of Steroid Hormones on Polycystic Ovary Syndrome and Clustering of Hyperandrogenism and Metabolic Factors.

OBJECTIVE: We determined (1) if 11-oxygenated androgens better identify polycystic ovary syndrome (PCOS) diagnosis in women with obesity compared to total or free testosterone (T) and free androgen index; (2) how biochemical hyperandrogenism and metabolic factors cluster in a cohort of women with infertility and obesity. METHODS: Women with obesity and PCOS comprised the study group (N = 132). Ovulatory women with obesity and idiopathic, tubal or male factor infertility were the control group (N = 83). Steroid hormones were measured by means of liquid chromatography tandem mass spectrometry. Receiver operating characteristic curves and principal component analysis were used. RESULTS: Women with obesity and PCOS had higher 11-ketotestosterone (11 KT) (1.22 nmol/L [0.84; 1.65] vs 1.05 [0.78; 1.35], P = .04) compared to controls, but not 11ß-hydroxyandrostenedione 4.30 [2.87; 5.92] vs 4.06 [3.22; 5.73], P = .44). 11-ketotestosterone (area under the curve: 0.59) did not better discriminate PCOS in women with obesity compared to: total T (0.84), free T (0.91), and free androgen index (0.85). We identified 4 principal components (PCs) in the PCOS group (72.1% explained variance): (1) insulin resistance status; (2) blood pressure; (3) obesity; (4) androgen status and 4 PCs in the control group (68.7% explained variance) with variables representing metabolism being dispersed in component 2, 3, and 4. CONCLUSIONS: Eleven-oxygenated androgens do not aid in the diagnosis of PCOS in women with obesity. Insulin resistance is the strongest PC in the PCOS group. There is no major dominant characteristic that defines obese non-PCOS women.

Report from the HarmoSter study: different LC-MS/MS androstenedione, DHEAS and testosterone methods compare well; however, unifying calibration is a double-edged sword.

OBJECTIVES: Current liquid chromatography-tandem mass spectrometry (LC-MS/MS) applications for circulating androgen measurements are technically diverse. Previously, variable results have been reported for testosterone. Data are scarce for androstenedione and absent for dehydroepiandrosterone sulfate (DHEAS). We assessed the agreement of androstenedione, DHEAS and testosterone LC-MS/MS measurements among nine European centers and explored benefits of calibration system unification. METHODS: Androgens were measured twice by laboratory-specific procedures in 78 patient samples and in EQA materials. Results were obtained by in-house and external calibration. Intra- and inter-laboratory performances were valued. RESULTS: Intra-laboratory CVs ranged between 4.2-13.2 % for androstenedione, 1.6-10.8 % for DHEAS, and 4.3-8.7 % and 2.6-7.1 % for female and male testosterone, respectively. Bias and trueness in EQA materials were within ±20 %. Median inter-laboratory CV with in-house vs. external calibration were 12.0 vs. 9.6 % for androstenedione (p<0.001), 7.2 vs. 4.9 % for DHEAS (p<0.001), 6.4 vs. 7.6 % for female testosterone (p<0.001) and 6.8 and 7.4 % for male testosterone (p=0.111). Median bias vs. all laboratory median with in-house and external calibration were -13.3 to 20.5 % and -4.9 to 18.7 % for androstenedione, -10.9 to 4.8 % and -3.4 to 3.5 % for DHEAS, -2.7 to 6.5 % and -11.3 to 6.6 % for testosterone in females, and -7.0 to 8.5 % and -7.5 to 11.8 % for testosterone in males, respectively. CONCLUSIONS: Methods showed high intra-laboratory precision but variable bias and trueness. Inter-laboratory agreement was remarkably good. Calibration system unification improved agreement in androstenedione and DHEAS, but not in testosterone measurements. Multiple components, such as commutability of calibrators and EQA materials and internal standard choices, likely contribute to inter-laboratory variability.

Tissue Glucocorticoid Metabolism in Adrenal Insufficiency: A Prospective Study of Dual-release Hydrocortisone Therapy.

BACKGROUND: Patients with adrenal insufficiency (AI) require life-long glucocorticoid (GC) replacement therapy. Within tissues, cortisol (F) availability is under the control of the isozymes of 11ß-hydroxysteroid dehydrogenase (11ß-HSD). We hypothesize that corticosteroid metabolism is altered in patients with AI because of the nonphysiological pattern of current immediate release hydrocortisone (IR-HC) replacement therapy. The use of a once-daily dual-release hydrocortisone (DR-HC) preparation, (Plenadren®), offers a more physiological cortisol profile and may alter corticosteroid metabolism in vivo. STUDY DESIGN AND METHODS: Prospective crossover study assessing the impact of 12 weeks of DR-HC on systemic GC metabolism (urinary steroid metabolome profiling), cortisol activation in the liver (cortisone acetate challenge test), and subcutaneous adipose tissue (microdialysis, biopsy for gene expression analysis) in 51 patients with AI (primary and secondary) in comparison to IR-HC treatment and age- and BMI-matched controls. RESULTS: Patients with AI receiving IR-HC had a higher median 24-hour urinary excretion of cortisol compared with healthy controls (72.1 µg/24 hours [IQR 43.6-124.2] vs 51.9 µg/24 hours [35.5-72.3], P = .02), with lower global activity of 11ß-HSD2 and higher 5-alpha reductase activity. Following the switch from IR-HC to DR-HC therapy, there was a significant reduction in urinary cortisol and total GC metabolite excretion, which was most significant in the evening. There was an increase in 11ß-HSD2 activity. Hepatic 11ß-HSD1 activity was not significantly altered after switching to DR-HC, but there was a significant reduction in the expression and activity of 11ß-HSD1 in subcutaneous adipose tissue. CONCLUSION: Using comprehensive in vivo techniques, we have demonstrated abnormalities in corticosteroid metabolism in patients with primary and secondary AI receiving IR-HC. This dysregulation of pre-receptor glucocorticoid metabolism results in enhanced glucocorticoid activation in adipose tissue, which was ameliorated by treatment with DR-HC.

Serum cortisol assay performance following the 1 mg overnight dexamethasone suppression test.

BACKGROUND: The 1 mg overnight dexamethasone suppression test (ONDST) is recommended for the differential diagnosis of Cushing's syndrome and the investigation of adrenal incidentalomas. Despite documented variation in serum cortisol immunoassay performance, little has been published regarding its effect on the ONDST. AIMS: Assess the performance of three immunoassay platforms (Roche Elecsys II, Abbott Alinity & Siemens Centaur) when compared to a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. METHODS: Samples (n = 77) sent to the laboratory as part of an ONDST were retrieved prior to disposal, anonymized, and analysed on all platforms. Samples with factors impacting immunoassay analysis quality were excluded. Results were statistically compared to an LC-MS/MS method that previously demonstrated excellent comparability to a candidate reference method. RESULTS: The Roche gen II showed a mean bias of -2.4 nmol/L and a Passing-Bablok fit of y = -0.9 + 0.97x. This was not affected by sex. The Abbott showed a mean bias -18.8 nmol/L, and a fit of y = -11.3 + 0.88x. This bias was -20.7 nmol/L in females versus -17.2 nmol/L in males. The Siemens had a mean bias of 2.3 nmol/L and a fit of y = 1.4 + 1.07x. This bias was 5.7 nmol/L in males versus -1.0 nmol/L in females. CONCLUSIONS: Clinicians should be aware of the method-dependent variation that exists within serum cortisol analysis during the ONDSTs. Roche and Siemens aligned more closely with LC-MS/MS while the Abbot may cause a reduction in ONDST sensitivity. This data supports assay-specific cut-offs for the ONDST.

Classic and 11-oxygenated androgens in serum and saliva across adulthood: a cross-sectional study analyzing the impact of age, body mass index, and diurnal and menstrual cycle variation.

OBJECTIVE: 11-oxygenated androgens significantly contribute to the circulating androgen pool. Understanding the physiological variation of 11-oxygenated androgens and their determinants is essential for clinical interpretation, for example, in androgen excess conditions. We quantified classic and 11-oxygenated androgens in serum and saliva across the adult age and body mass index (BMI) range, also analyzing diurnal and menstrual cycle-dependent variation. DESIGN: Cross-sectional. Morning serum samples were collected from 290 healthy volunteers (125 men, 22-95 years; 165 women, 21-91 years). Morning saliva samples were collected by a sub-group (51 women and 32 men). Diurnal saliva profiles were collected by 13 men. Twelve women collected diurnal saliva profiles and morning saliva samples on 7 consecutive days during both follicular and luteal menstrual cycle phases. METHODS: Serum and salivary steroids were quantified by liquid chromatography-tandem mass spectrometry profiling assays. RESULTS: Serum classic androgens decreased with age-adjusted BMI, for example, %change kg/m2 for 5α-dihydrotestosterone: men -5.54% (95% confidence interval (CI) -8.10 to -2.98) and women -1.62% (95%CI -3.16 to -0.08). By contrast, 11-oxygenated androgens increased with BMI, for example, %change kg/m2 for 11-ketotestosterone: men 3.05% (95%CI 0.08-6.03) and women 1.68% (95%CI -0.44 to 3.79). Conversely, classic androgens decreased with age in both men and women, while 11-oxygenated androgens did not. Salivary androgens showed a diurnal pattern in men and in the follicular phase in women; in the luteal phase, only 11-oxygenated androgens showed diurnal variation. CONCLUSIONS: Classic androgens decrease while active 11-oxygenated androgens increase with increasing BMI, pointing toward the importance of adipose tissue mass for the activation of 11-oxygenated androgens. Classic but not 11-oxygenated androgens decline with age.

11-Oxygenated androgens are not secreted by the human ovary: in-vivo data from four different cases of hyperandrogenism.

Objective: Differentiation of an adrenal from an ovarian source of hyperandrogenemia can be challenging. Recent studies have highlighted the importance of 11-oxygenated C19 steroids to the androgen pool in humans. The aim of this study was to confirm the origin of 11-oxygenated androgens in females and to explore their potential use in the diagnostics of hyperandrogenic disorders. Methods: We measured testosterone and its precursors (dehydroepiandrosterone-sulfate and androstenedione) and 11-oxygenated androgens (11ß-hydroxyandrostenedione (11-OHA4) and 11-ketotestosterone (11-KT)) in the periphery, adrenal and ovarian veins in four different cases of hyperandrogenism in females (polycystic ovary syndrome (PCOS), primary bilateral macronodular adrenal hyperplasia, Sertoli-Leydig cell tumor and ovarian steroid cell tumor). Results: Two patients demonstrate excessive testosterone secretion in neoplastic ovarian tumors which was not paralleled by a significant secretion of 11-oxygenated androgens as determined by adrenal and ovarian vein sampling. In androgen-secreting bilateral adrenal macronodular hyperplasia, steroid profiles were characterized by elevated 11-KT and 11-OHA4 concentrations in adrenal veins and the periphery. In the patient with PCOS, peripheral 11-KT concentrations were slightly elevated in comparison to the other patients, but the 11-KT and 11-OHA4 concentrations were comparable in ovarian veins and in the periphery. Conclusion: This study confirms that 11-OHA4 and 11-KT are not biosynthesized by the ovary. We propose that the testosterone/11-KT ratio as well as 11-OHA4 could help identify predominant adrenal androgen excess and distinguish neoplastic and non-neoplastic ovarian androgen source. Significance statement: This study confirms that 11ß-hydroxyandrostenedione (11-OHA4) and 11-ketotestosterone (11-KT) are not biosynthesized by the human ovary. We propose that the testosterone/11-KT ratio as well as 11-OHA4 could help to identify predominant adrenal androgen excess and distinguish neoplastic and non-neoplastic ovarian androgen source.

Multi-steroid profiling by UHPLC-MS/MS with post-column infusion of ammonium fluoride.

BACKGROUND: Multi-steroid profiling is a powerful analytical tool that simultaneously quantifies steroids from different biosynthetic pathways. Here we present an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay for the profiling of 23 steroids using post-column infusion of ammonium fluoride. METHODS: Following liquid-liquid extraction, steroids were chromatographically separated over 5 min using a Phenomenex Luna Omega C18 column and a water (0.1 % formic acid) methanol gradient. Quantification was performed on a Waters Acquity UHPLC and Xevo® TQ-XS mass spectrometer. Ammonium fluoride (6 mmol/L, post-column infusion) and formic acid (0.1 % (vol/vol), mobile phase additive) were compared as additives to aid ionisation. RESULTS: Post-column infusion of ammonium fluoride enhanced ionisation in a steroid structure-dependent fashion compared to formic acid (122-140 % for 3ßOH-Δ5 steroids and 477-1274 % for 3-keto-Δ4 steroids). Therefore, we analytically validated post-column infusion of ammonium fluoride. Lower limits of quantification ranged from 0.3 to 3 nmol/L; All analytes were quantifiable with acceptable accuracy (bias range -14 % to 11.9 % for 21/23, -21 % to 11.9 % for all analytes). Average recovery ranged from 91.6 % to 113.6 % and average matrix effects from -29.9 % to 19.9 %. Imprecision ranged from 2.3 % to 23 % for all analytes and was < 15 % for 18/23 analytes. The serum multi-steroid profile of 10 healthy men and 10 healthy women was measured. CONCLUSIONS: UHPLC-MS/MS with post-column infusion of ammonium fluoride enables comprehensive multi-steroid profiling through enhanced ionisation particularly benefiting the detection of 3-keto-Δ4 steroids.

Report from the HarmoSter study: impact of calibration on comparability of LC-MS/MS measurement of circulating cortisol, 17OH-progesterone and aldosterone.

OBJECTIVES: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is recommended for measuring circulating steroids. However, assays display technical heterogeneity. So far, reproducibility of corticosteroid LC-MS/MS measurements has received scant attention. The aim of the study was to compare LC-MS/MS measurements of cortisol, 17OH-progesterone and aldosterone from nine European centers and assess performance according to external quality assessment (EQA) materials and calibration. METHODS: Seventy-eight patient samples, EQA materials and two commercial calibration sets were measured twice by laboratory-specific procedures. Results were obtained by in-house (CAL1) and external calibrations (CAL2 and CAL3). We evaluated intra and inter-laboratory imprecision, correlation and agreement in patient samples, and trueness, bias and commutability in EQA materials. RESULTS: Using CAL1, intra-laboratory CVs ranged between 2.8-7.4%, 4.4-18.0% and 5.2-22.2%, for cortisol, 17OH-progesterone and aldosterone, respectively. Trueness and bias in EQA materials were mostly acceptable, however, inappropriate commutability and target value assignment were highlighted in some cases. CAL2 showed suboptimal accuracy. Median inter-laboratory CVs for cortisol, 17OH-progesterone and aldosterone were 4.9, 11.8 and 13.8% with CAL1 and 3.6, 10.3 and 8.6% with CAL3 (all p<0.001), respectively. Using CAL1, median bias vs. all laboratory-medians ranged from -6.6 to 6.9%, -17.2 to 7.8% and -12.0 to 16.8% for cortisol, 17OH-progesterone and aldosterone, respectively. Regression lines significantly deviated from the best fit for most laboratories. Using CAL3 improved cortisol and 17OH-progesterone between-method bias and correlation. CONCLUSIONS: Intra-laboratory imprecision and performance with EQA materials were variable. Inter-laboratory performance was mostly within specifications. Although residual variability persists, adopting common traceable calibrators and RMP-determined EQA materials is beneficial for standardization of LC-MS/MS steroid measurements.

Quantification of testosterone, androstenedione and 17-hydroxyprogesterone in whole blood collected using Mitra microsampling devices.

BACKGROUND: Measurement of testosterone (T), androstenedione (A4) and 17-hydroxyprogesterone (17OHP) usually requires a venous serum sample which may have implications for sample stability or collection. OBJECTIVE: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed for samples collected using Mitra devices. Analytical validation was completed, and sample comparisons were undertaken to assess Mitra versus venous samples. METHOD: Sample was combined with deionized water and internal standard. After mixing, MTBE was added for extraction. The supernatant was transferred to a deep-well plate and dried prior to re-constitution. A HSS T3 column and Waters TQS Micro was used, the detected quantifier transitions were T m/z 289.2 > 96.95, A4 287.2 > 96.95 and 17OHP 331.25 > 96.95. RESULTS: Mean recovery was 102% for T, 98% for A4 and 97% for 17OHP. Lower limit of quantification was 1 nmol/L for T/A4 and 4 nmol/L for 17OHP. T was linear up to 41.6 nmol/L, A4 41.9 nmol/L and 17OHP 72.6 nmol/L. Ion suppression was <10% for all analytes. A4 and 17OHP showed minimal bias for Mitra samples collected from finger prick blood. The bias for T differed between capillary and venous blood, indicating differences in constituency. DISCUSSION: A simple, fast and reproducible LC-MS/MS assay has been developed for measurement of blood collected using Mitra devices for T, A4 and 17OHP. Further comparisons with serum and capillary blood collected onto Mitra devices serum may pave the way for future use in a clinical setting.

Development of a total serum testosterone, androstenedione, 17-hydroxyprogesterone, 11ß-hydroxyandrostenedione and 11-ketotestosterone LC-MS/MS assay and its application to evaluate pre-analytical sample stability.

Background Classically, serum testosterone (T) and androstenedione (A4) have been the mainstay for the biochemical assessment of hyperandrogenism. However, recent evidence suggests 11ß-hydroxyandrostenedione (11OHA4) and 11-ketotestosterone (11KT) may also be important. Here, we describe the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for quantitation of total serum T, A4, 17-hydroxyprogesterone (17OHP), 11OHA4 and 11KT. In addition, we applied the method to assess pre-analytical stability. Methods An isotopically labelled internal standard was added to samples prior to supported liquid extraction (SLE). Extracts were analysed using LC-MS/MS to detect T/A4/17OHP/11OHA4 and 11KT along with their corresponding internal standards. Samples (n = 7) were collected from healthy volunteers (n = 14) and left incubated at 20 °C for up to 72 h. Tubes were retrieved at select time points, centrifuged, separated and frozen prior to analysis. Results The total run time was 4 min. For all analytes, intra- and inter-assay imprecision did not exceed 7.9% and 5.3%, respectively; matrix effects were negligible and mean recoveries ranged from 95.3 to 111.6%. The limits of quantitation (LOQs) were 0.25 nmol/L for T, A4 and 11OHA4, 0.50 nmol/L for 17OHP, and 0.24 nmol/L for 11KT. No significant change was observed in pre-centrifugation A4 or female T concentrations over 72 h. Significant increases (p < 0.01) in concentrations of 11KT, 17OHP, 11OHA4 and male T were observed after 2, 8, 12 and 24 h, respectively. Conclusions We developed a robust LC-MS/MS assay for the quantitation of total serum T/A4/17OHP/11OHA4 and 11KT. Applying the method to determine pre-analytical stability suggests samples requiring 11KT need separating from the cells within 2 h.

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.

Serum Cortisol: An Up-To-Date Assessment of Routine Assay Performance.

BACKGROUND: Accurate serum cortisol quantification is required for the correct diagnosis and management of adrenal pathologies. Presently, most laboratories use immunoassay to measure serum cortisol with proficiency schemes demonstrating a wide dispersion of results. Here, we investigate the effects of sex, matrix, and antibody specificity on serum cortisol quantification in 6 routine assays. METHODS: Surplus serum was obtained before disposal and the following cohorts were created: males, nonpregnant females, pregnant patients, and patients prescribed either metyrapone or prednisolone. Samples were anonymized and distributed to collaborating laboratories for cortisol analysis by 6 routine assays. Cortisol was also measured in all samples using an LC-MS/MS candidate reference measurement procedure (cRMP); cortisol-binding globulin (CBG) was measured in the nonpregnant and pregnant female cohorts. RESULTS: Considerable inter- and intraassay variation was observed across the male and nonpregnant female cohorts relative to the cRMP. Four immunoassays underrecovered cortisol in the pregnancy cohort, and CBG was found to be significantly higher in this cohort than in the nonpregnant females. In the metyrapone and prednisolone cohorts, all immunoassays overestimated cortisol. The first generation Roche E170 and Siemens Centaur XP were particularly prone to overestimation. In all cohorts the routine LC-MS/MS assay aligned extremely well with the cRMP. CONCLUSIONS: Despite the clinical importance of serum cortisol, the performance of routine immunoassays remains highly variable. Accurate quantification is compromised by both matrix effects and antibody specificity. Underpinning this study with a cRMP has highlighted the deficiencies in standardization across routine cortisol immunoassays.

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.

Candidate Reference Measurement Procedure for the Quantification of Total Serum Cortisol with LC-MS/MS.

BACKGROUND: Accurate measurement of serum cortisol is required to diagnose and treat adrenal disorders. Although certified reference materials (CRMs) are available to standardize cortisol measurements, External Quality Assessment (EQA) schemes still demonstrate a wide dispersion of results. We present a serum cortisol candidate reference measurement procedure that, through analysis of a Joint Committee for Traceability in Laboratory Medicine-listed panel of higher-order CRMs, provides metrologically traceable results. METHOD: Isotope-labeled internal standard was added to samples before supported liquid extraction. Extracts were analyzed with LC-MS/MS in positive electrospray ionization mode. Multiple reaction monitoring was used to detect cortisol and its corresponding internal standard transitions. We measured samples in triplicate over 3 days and calculated the mean result. RESULTS: Mean intra- and interassay imprecision were 1.3% and 1.5%, respectively, for concentrations of 154, 510, and 769 nmol/L. Ionization efficiency studies and structural analog analysis proved the method to be robust against interferences. Through analysis of 34 CRMs (83-764 nmol/L), expanded measurement uncertainty was calculated to be 5% (95% CI). The mean bias between the measured and target CRM concentrations was statistically insignificant at -0.08%. CONCLUSIONS: The accuracy and low measurement uncertainty of this method qualify it as a CRM procedure. Metrological traceability has been achieved through the analysis of higher-order CRMs. This method could be used to underpin serum cortisol EQA schemes to provide samples with a traceable target value, enabling participating laboratories to determine the accuracy and measurement uncertainty of their assays.