1
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Thirkettle S, Blaszczyk P, Evans R, Wheatley M, Abbas M, Russell J, Monaghan PJ. Stability assessment of serum tumour markers: Calcitonin, chromogranin A, thyroglobulin and anti-thyroglobulin antibodies. Ann Clin Biochem 2023; 60:212-216. [PMID: 36867512 DOI: 10.1177/00045632231160371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
BACKGROUND There is limited published data on the stability of calcitonin, chromogranin A, thyroglobulin and anti-thyroglobulin antibodies in serum. The aim of this study was to determine stability at three temperature conditions over 7 days, reflecting current laboratory practices. METHODS Surplus serum was stored at room temperature, refrigerated and in the freezer; for 1, 3, 5 and 7 days. Samples were analysed in batch and analyte concentrations compared to that of a baseline sample. Measurement Uncertainty of the assay was used to determine the Maximal Permissible Difference and thus the stability of the analyte. RESULTS Calcitonin was found to be stable for at least 7 days in the freezer but only 24 h refrigerated. Chromogranin A was stable for 3 days when refrigerated and only 24 h at room temperature. Thyroglobulin and anti-thyroglobulin antibodies were stable under all conditions for 7 days. CONCLUSION This study has enabled the laboratory to increase the add-on time limit of Chromogranin A to 3 days, and up to 60 min for calcitonin and inform optimal storage and transportation conditions for referring specimens.
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Affiliation(s)
| | | | - Rachel Evans
- 5294Christie Pathology Partnership, Manchester, UK
| | | | | | | | - Phillip J Monaghan
- 5294Christie Pathology Partnership, Manchester, UK.,The Division of Cancer Sciences, University of Manchester, Manchester, UK
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2
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Howell SJ, Keevil B, Higham C, Owen LJ, Monaghan PJ. RE: Fulvestrant falsely elevates oestradiol levels in immunoassays in postmenopausal women with breast cancer. Eur J Cancer 2020; 136:204-205. [PMID: 32665169 DOI: 10.1016/j.ejca.2020.04.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 04/04/2020] [Accepted: 04/11/2020] [Indexed: 10/23/2022]
Affiliation(s)
- Sacha J Howell
- The Christie NHS Foundation Trust, Wilmslow Road, Manchester, M204BX, UK.
| | - Brian Keevil
- Manchester University NHS Foundation Trust, Southmoor Road, Wythenshawe, Manchester, M23 9LT, UK.
| | - Claire Higham
- The Christie NHS Foundation Trust, Wilmslow Road, Manchester, M204BX, UK.
| | - Laura J Owen
- Salford Royal NHS Foundation Trust, Stott Ln, Salford, M6 8HD, UK.
| | - Phillip J Monaghan
- The Christie NHS Foundation Trust, Wilmslow Road, Manchester, M204BX, UK.
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3
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Williams EH, Connell CM, Weaver JMJ, Beh I, Potts H, Whitley CT, Bird N, Al-Sayed T, Monaghan PJ, Fehr M, Cathomas R, Bertelli G, Quinton A, Lewis P, Shamash J, Wilson P, Dooley M, Poole S, Mark PB, Bookman MA, Earl H, Jodrell D, Tavaré S, Lynch AG, Janowitz T. Multicenter Validation of the CamGFR Model for Estimated Glomerular Filtration Rate. JNCI Cancer Spectr 2019; 3:pkz068. [PMID: 31750418 PMCID: PMC6846361 DOI: 10.1093/jncics/pkz068] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 07/13/2019] [Accepted: 08/23/2019] [Indexed: 11/14/2022] Open
Abstract
Important oncological management decisions rely on kidney function assessed by serum creatinine-based estimated glomerular filtration rate (eGFR). However, no large-scale multicenter comparisons of methods to determine eGFR in patients with cancer are available. To compare the performance of formulas for eGFR based on routine clinical parameters and serum creatinine not calibrated with isotope dilution mass spectrometry, we studied 3620 patients with cancer and 166 without cancer who had their glomerular filtration rate (GFR) measured with an exogenous nuclear tracer at one of seven clinical centers. The mean measured GFR was 86 mL/min. Accuracy of all models was center dependent, reflecting intercenter variability of isotope dilution mass spectrometry-creatinine measurements. CamGFR was the most accurate model for eGFR (root-mean-squared error 17.3 mL/min) followed by the Chronic Kidney Disease Epidemiology Collaboration model (root-mean-squared error 18.2 mL/min).
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Affiliation(s)
- Edward H Williams
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Claire M Connell
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
- Cambridge University Hospital NHS Trust, Cambridge, UK
- Department of Oncology, University of Cambridge, UK
| | | | - Ian Beh
- Western General Hospital, Edinburgh, UK
| | - Harry Potts
- School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | | | - Nicholas Bird
- Cambridge University Hospital NHS Trust, Cambridge, UK
| | | | - Phillip J Monaghan
- The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK
- University of Manchester, Faculty of Medical and Human Sciences, Institute of Inflammation and Repair, Manchester, UK
| | - Martin Fehr
- Clinic for Medical Oncology and Hematology, Cantonal Hospital St Gallen, Switzerland
| | - Richard Cathomas
- Division of Oncology/Hematology, Cantonal Hospital Graubünden, Switzerland
| | - Gianfilippo Bertelli
- Sussex Cancer Centre, Brighton and Sussex University Hospitals NHS Trust, Brighton, UK
| | | | - Paul Lewis
- Institute of Life Science, Medical School, Swansea University, Swansea, UK
| | - Jonathan Shamash
- Department of Medical Oncology, St Bartholomew's Hospital, West Smithfield, London, UK
| | - Peter Wilson
- Department of Medical Oncology, St Bartholomew's Hospital, West Smithfield, London, UK
| | - Michael Dooley
- Alfred Health, Melbourne, Australia
- Monash University, Melbourne, Australia
| | - Susan Poole
- Alfred Health, Melbourne, Australia
- Monash University, Melbourne, Australia
| | - Patrick B Mark
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | | | - Helena Earl
- Cambridge University Hospital NHS Trust, Cambridge, UK
- Department of Oncology, University of Cambridge, UK
- NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Duncan Jodrell
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
- Cambridge University Hospital NHS Trust, Cambridge, UK
| | - Simon Tavaré
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
- Columbia University, New York, NY
| | - Andy G Lynch
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
- School of Medicine/School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Tobias Janowitz
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY
- Northwell Health, New York, NY
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4
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Adaway J, Keevil B, Miller A, Monaghan PJ, Merrett N, Owen L. Ramifications of variability in sex hormone-binding globulin measurement by different immunoassays on the calculation of free testosterone. Ann Clin Biochem 2019; 57:88-94. [DOI: 10.1177/0004563219888549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Objective Sex hormone-binding globulin (SHBG) is a glycoprotein which binds hormones such as testosterone. Around 97% of circulating testosterone is bound to SHBG or albumin and is therefore biologically unavailable; 2–3% of testosterone is free. Free testosterone is very technically challenging to quantify; in order to circumvent this problem, equations using testosterone and SHBG are used to estimate free testosterone. We decided to determine the effect of using different SHBG immunoassays on calculated free testosterone results. Design Anonymized surplus serum samples were analysed for SHBG on four different immunoassay platforms (Abbott Architect, Roche, Beckman and Siemens). The SHBG results were used to generate a Vermeulen calculated free testosterone. Results Beckman Access and Siemens Centaur both gave results close to the overall mean. Roche gave the highest SHBG concentrations with Abbott Architect producing the lowest results. Abbott Architect gave the highest calculated free testosterone results, followed by Beckman. Roche gave the lowest results. Sixty-five per cent of male samples had low calculated free testosterone and 27.5% of the females had high calculated free testosterone using the SHBG from the Abbott assay compared with 69% low male calculated free testosterone and 20% high female calculated free testosterone with the Roche assay. Conclusion Our results have shown significant differences in SHBG results produced by different analysers and subsequently the calculated free testosterone, which may affect result interpretation if method-specific reference ranges for calculated free testosterone are not used. Care should be taken to ensure reference ranges are appropriate for the analyser used to avoid misdiagnosis of hypo or hyperandrogenism, and ensure patients get the most appropriate treatment.
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Affiliation(s)
- Joanne Adaway
- Department of Clinical Biochemistry, Manchester University Hospital NHS Foundation Trust, Wythenshawe Hospital, Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, University of Manchester, Manchester, UK
| | - Brian Keevil
- Department of Clinical Biochemistry, Manchester University Hospital NHS Foundation Trust, Wythenshawe Hospital, Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, University of Manchester, Manchester, UK
| | - Annmarie Miller
- Clinical Biochemistry Department, University Hospital Aintree, Lower Lane, Liverpool, UK
| | - Phillip J Monaghan
- Faculty of Medical and Human Sciences, Institute of Inflammation and Repair, University of Manchester, Manchester, UK
- The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK
| | - Nicola Merrett
- Department of Laboratory Medicine, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Laura Owen
- Department of Clinical Biochemistry, Manchester University Hospital NHS Foundation Trust, Wythenshawe Hospital, Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, University of Manchester, Manchester, UK
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5
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Monaghan PJ, Trainer PJ. Determinants of the growth hormone nadir during oral glucose tolerance test in adults. Eur J Endocrinol 2019; 181:C17-C20. [PMID: 31480015 DOI: 10.1530/eje-19-0661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 09/02/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Phillip J Monaghan
- Department of Clinical Biochemistry, The Christie Pathology Partnership, The Christie NHS Foundation Trust; University of Manchester, Faculty of Medical and Human Sciences, Institute of Inflammation and Repair, Manchester, UK
| | - Peter J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust; University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
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6
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Lord SJ, St John A, Bossuyt PM, Sandberg S, Monaghan PJ, O'Kane M, Cobbaert CM, Röddiger R, Lennartz L, Gelfi C, Horvath AR. Setting clinical performance specifications to develop and evaluate biomarkers for clinical use. Ann Clin Biochem 2019; 56:527-535. [PMID: 30987429 DOI: 10.1177/0004563219842265] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Biomarker discovery studies often claim ‘promising’ findings, motivating further studies and marketing as medical tests. Unfortunately, the patient benefits promised are often inadequately explained to guide further evaluation, and few biomarkers have translated to improved patient care. We present a practical guide for setting minimum clinical performance specifications to strengthen clinical performance study design and interpretation. Methods We developed a step-by-step approach using test evaluation and decision-analytic frameworks and present with illustrative examples. Results We define clinical performance specifications as a set of criteria that quantify the clinical performance a new test must attain to allow better health outcomes than current practice. We classify the proposed patient benefits of a new test into three broad groups and describe how to set minimum clinical performance at the level where the potential harm of false-positive and false-negative results does not outweigh the benefits. (1) For add-on tests proposed to improve disease outcomes by improving detection, define an acceptable trade-off for false-positive versus true-positive results; (2) for triage tests proposed to reduce unnecessary tests and treatment by ruling out disease, define an acceptable risk of false-negatives as a safety threshold; (3) for replacement tests proposed to provide other benefits, or reduce costs, without compromising accuracy, use existing tests to benchmark minimum accuracy levels. Conclusions Researchers can follow these guidelines to focus their study objectives and to define statistical hypotheses and sample size requirements. This way, clinical performance studies will allow conclusions about whether test performance is sufficient for intended use.
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Affiliation(s)
- Sarah J Lord
- 1 School of Medicine, University of Notre Dame, Darlinghurst, New South Wales, Australia.,2 National Health and Medical Research Council (NHMRC) Clinical Trials Centre, University of Sydney, Sydney, Australia
| | | | - Patrick Mm Bossuyt
- 4 Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Sverre Sandberg
- 5 Department of Global Public Health and Primary Health Care, University of Bergen, Norway.,6 The Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway.,7 Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway
| | - Phillip J Monaghan
- 8 Department of Clinical Biochemistry, The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK
| | - Maurice O'Kane
- 9 Clinical Chemistry Department, Altnagelvin Hospital, Western Health and Social Care Trust, Londonderry, UK
| | - Christa M Cobbaert
- 10 Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Ralf Röddiger
- 9 Clinical Chemistry Department, Altnagelvin Hospital, Western Health and Social Care Trust, Londonderry, UK.,11 Clinical Operations, Global Medical and Scientific Affairs, Roche Diagnostics GmbH, Mannheim, Germany
| | | | - Cecilia Gelfi
- 13 Department of Biomedical Sciences for Health, University of Milano, Milan, Italy
| | - Andrea R Horvath
- 14 Department of Clinical Chemistry & Endocrinology, Prince of Wales Hospital, New South Wales Health Pathology and School of Medical Sciences, University of New South Wales, Randwick, Australia.,15 School of Public Health, University of Sydney, Camperdown, Australia
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7
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Monaghan PJ, Bossuyt PM. Test evaluation: major challengesahead - Opportunities abound. Ann Clin Biochem 2019; 56:524-526. [PMID: 30971105 DOI: 10.1177/0004563219837301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Phillip J Monaghan
- 1 The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK.,2 Faculty of Medical and Human Sciences, Institute of Inflammation and Repair, University of Manchester, Manchester, UK
| | - Patrick Mm Bossuyt
- 3 Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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8
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Owen LJ, Monaghan PJ, Armstrong A, Keevil BG, Higham C, Salih Z, Howell S. Oestradiol measurement during fulvestrant treatment for breast cancer. Br J Cancer 2019; 120:404-406. [PMID: 30679781 PMCID: PMC6461991 DOI: 10.1038/s41416-019-0378-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 12/18/2018] [Accepted: 01/02/2019] [Indexed: 11/10/2022] Open
Abstract
Biochemical evaluation of menopausal status is used to inform treatment decisions, including clinical trial eligibility in women with oestrogen receptor positive breast cancer. However, fulvestrant may interfere with oestradiol immunoassays and confound accurate assessment in this context. We conducted a service evaluation of two immunoassays and an LC-MS/MS assay to determine the extent of the interference. Serum oestradiol levels were analysed by two immunoassays (Siemens Centaur XP and Abbott Architect) and liquid chromatography-tandem mass spectrometry (LC/MS/MS). Immunoassay gave higher serum oestradiol results than LC-MS/MS at low concentrations, with improved analytical sensitivity demonstrated by LC-MS/MS. Cross-reactivity of fulvestrant was observed for each immunoassay. We have shown that two commonly used immunoassays do not demonstrate the required sensitivity or specificity for the measurement of oestradiol in a breast cancer population. For patients receiving fulvestrant, spurious results may be generated that could impact treatment decisions. LC-MS/MS is recommended in this setting.
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Affiliation(s)
- Laura J Owen
- Biochemistry Department, Wythenshawe Hospital, Wythenshawe, M23 9LT, UK. .,School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
| | - Phillip J Monaghan
- The Christie Pathology Partnership. The Christie, Wilmslow Road, Manchester, M20 4BX, UK.,University of Manchester, Faculty of Medical and Human Sciences, Institute of Inflammation and Repair, Manchester, UK
| | - Anne Armstrong
- Medical Oncology, The Christie, Wilmslow Road, Manchester, M20 4BX, UK
| | - Brian G Keevil
- Biochemistry Department, Wythenshawe Hospital, Wythenshawe, M23 9LT, UK.,School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Claire Higham
- Endocrinology, The Christie, Wilmslow Road, Manchester, M20 4BX, UK
| | - Zena Salih
- Medical Oncology, The Christie, Wilmslow Road, Manchester, M20 4BX, UK
| | - Sacha Howell
- Medical Oncology, The Christie, Wilmslow Road, Manchester, M20 4BX, UK
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9
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Monaghan PJ, Lord S, St John A, Sandberg S, Cobbaert CM, Lennartz L, Verhagen-Kamerbeek WD, Ebert C, Bossuyt PM, Horvath AR. Biomarker Development and Evaluation Targeting Unmet Clinical Needs. Pathology 2018. [DOI: 10.1016/j.pathol.2017.12.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Monaghan PJ, Kyriacou A, Sturgeon C, Davies A, Trainer PJ, White A, Higham CE. Proopiomelanocortin interference in the measurement of adrenocorticotrophic hormone: a United Kingdom National External Quality Assessment Service study. Clin Endocrinol (Oxf) 2016; 85:569-74. [PMID: 27256168 DOI: 10.1111/cen.13118] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 04/04/2016] [Accepted: 05/25/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVE It is recognized that measurement of ACTH-precursor peptides including proopiomelanocortin (POMC) has clinical utility in identifying the aetiology of Cushing's syndrome. Recent data have also demonstrated cross-reactivity of POMC in ACTH immunoassays used in clinical laboratories. The aim of this study was to assess the cross-reactivity of POMC in the main commercial immunoassays for ACTH and to survey the awareness of laboratory professionals to this potential interference. METHOD To assess cross-reactivity, specimens containing ACTH and/or POMC were prepared by the UK National External Quality Assessment Service (UK NEQAS) [Edinburgh]. A separate interpretative exercise was also sent to participating laboratories. RESULTS Eighty-seven laboratories measured 'total' ACTH (i.e. ACTH and/or POMC) in their assays. Cross-reactivity of POMC varied from a mean of 1·6-4·7% (reflected in a large percentage increase in measured ACTH of up to 261% due to POMC cross-reactivity) depending on the manufacturer. Major differences in the clinical interpretation of test results were observed in returned responses to the interpretative exercise. CONCLUSION An appraisal of POMC cross-reactivity in currently available ACTH immunoassays has been achieved. Cross-reactivity was sufficient to detect ACTH precursors at concentrations that could be found in patients with ectopic ACTH syndrome. These data will assist laboratories in interpreting results when assessing the hypothalamic-pituitary-adrenal axis. Endocrinologists and laboratory professionals should be aware of the degree of cross-reactivity in ACTH immunoassay in order to minimize the risk of misinterpretation of results and/or potentially delayed treatment.
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Affiliation(s)
- P J Monaghan
- The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK.
| | - A Kyriacou
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester, UK
| | - C Sturgeon
- Department of Laboratory Medicine, UK NEQAS [Edinburgh], Royal Infirmary of Edinburgh, Edinburgh, UK
| | - A Davies
- Faculty of Life Sciences & Medical and Human Sciences, University of Manchester, Manchester, UK
| | - P J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester, UK
- Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - A White
- Faculty of Life Sciences & Medical and Human Sciences, University of Manchester, Manchester, UK
- Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - C E Higham
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester, UK
- Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
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11
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Hawley JM, Owen LJ, Lockhart SJ, Monaghan PJ, Armston A, Chadwick CA, Wilshaw H, Freire M, Perry L, Keevil BG. Serum Cortisol: An Up-To-Date Assessment of Routine Assay Performance. Clin Chem 2016; 62:1220-9. [DOI: 10.1373/clinchem.2016.255034] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/17/2016] [Indexed: 11/06/2022]
Abstract
Abstract
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.
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Affiliation(s)
| | - Laura J Owen
- University Hospital South Manchester, Manchester, UK
- Manchester Academic Health Science Centre, Manchester, UK
| | | | - Phillip J Monaghan
- The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK
| | | | | | | | | | | | - Brian G Keevil
- University Hospital South Manchester, Manchester, UK
- Manchester Academic Health Science Centre, Manchester, UK
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12
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Monaghan PJ, Lord SJ, St John A, Sandberg S, Cobbaert CM, Lennartz L, Verhagen-Kamerbeek WDJ, Ebert C, Bossuyt PMM, Horvath AR. Biomarker development targeting unmet clinical needs. Clin Chim Acta 2016; 460:211-9. [PMID: 27374304 DOI: 10.1016/j.cca.2016.06.037] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND The introduction of new biomarkers can lead to inappropriate utilization of tests if they do not fill in existing gaps in clinical care. We aimed to define a strategy and checklist for identifying unmet needs for biomarkers. METHODS A multidisciplinary working group used a 4-step process: 1/ scoping literature review; 2/ face-to-face meetings to discuss scope, strategy and checklist items; 3/ iterative process of feedback and consensus to develop the checklist; 4/ testing and refinement of checklist items using case scenarios. RESULTS We used clinical pathway mapping to identify clinical management decisions linking biomarker testing to health outcomes and developed a 14-item checklist organized into 4 domains: 1/ identifying and 2/ verifying the unmet need; 3/ validating the intended use; and 4/ assessing the feasibility of the new biomarker to influence clinical practice and health outcome. We present an outcome-focused approach that can be used by multiple stakeholders for any medical test, irrespective of the purpose and role of testing. CONCLUSIONS The checklist intends to achieve more efficient biomarker development and translation into practice. We propose the checklist is field tested by stakeholders, and advocate the role of the clinical laboratory professional to foster trans-sector collaboration in this regard.
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Affiliation(s)
- Phillip J Monaghan
- Department of Clinical Biochemistry, The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK.
| | - Sarah J Lord
- School of Medicine, University of Notre Dame, Australia; National Health and Medical Research Council (NHMRC) Clinical Trials Centre, University of Sydney, Australia
| | | | - Sverre Sandberg
- The Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway; Department of Public Health and Primary Health Care, University of Bergen, Norway; Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway
| | - Christa M Cobbaert
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, The Netherlands
| | | | | | - Christoph Ebert
- Medical and Scientific Affairs, Roche Diagnostics GmbH, Penzberg, Germany
| | - Patrick M M Bossuyt
- Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Andrea R Horvath
- SEALS Department of Clinical Chemistry and Endocrinology, Prince of Wales Hospital and School of Medical Sciences, University of New South Wales, Australia; Screening and Test Evaluation Program, School of Public Health, University of Sydney, Australia
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13
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Monaghan PJ, Lamarca A, Valle JW, Hubner RA, Mansoor W, Trainer PJ, Darby D. Routine measurement of plasma chromogranin B has limited clinical utility in the management of patients with neuroendocrine tumours. Clin Endocrinol (Oxf) 2016; 84:348-52. [PMID: 26608723 DOI: 10.1111/cen.12985] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/16/2015] [Accepted: 11/18/2015] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Chromogranin A (CgA) and B (CgB) are markers for monitoring disease status in patients with gastroenteropancreatic neuroendocrine tumours (NETs). These are specialized diagnostic tests often necessitating referral of specimens to a supraregional assay service (SAS) laboratory for analysis. The aim of this audit was to assess whether measurement of either plasma CgA or CgB alone provides sufficient clinical information in comparison with the current practice of measuring both markers together. DESIGN A retrospective analysis was undertaken for all chromogranin tests requested for patients with a known NET diagnosis. Results were categorized based on whether plasma concentrations were elevated for one or both CgA and CgB. RESULTS A total of 325 sequential patients with a NET diagnosis had plasma chromogranin levels measured during the period of review. Baseline CgA was elevated in 60·9% of patients. Isolated elevations in CgA (with normal CgB) were found in 44·9% of patients, whilst combined elevations in both CgA and CgB were found in 16% of patients. Combined CgA and CgB concentrations within the normal range were observed for 38·5% of patients. Only two patients (0·6%) had an isolated elevation in CgB at baseline. Both patients had a diagnosis of pancreatic NET and were radiologically stable. Plasma CgA and CgB corresponded with disease stage (localized vs metastatic). CgB in addition to CgA did not provide any significant improvement in diagnostic performance for identification of metastatic disease compared to CgA alone. CONCLUSIONS Based on this NET population and specific assay performance characteristics, CgA alone provides sufficient information for the management of NET patients; the routine estimation of CgB in all patients is not informative in clinical practice.
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Affiliation(s)
- P J Monaghan
- The Christie Pathology Partnership, The Christie NHS Foundation Trust, Manchester, UK
| | - A Lamarca
- Department of Medical Oncology, The Christie NHS Foundation Trust and ENETS Centre of Excellence, Manchester, UK
| | - J W Valle
- Department of Medical Oncology, The Christie NHS Foundation Trust and ENETS Centre of Excellence, Manchester, UK
- Institute of Cancer Sciences, University of Manchester, Manchester, UK
| | - R A Hubner
- Department of Medical Oncology, The Christie NHS Foundation Trust and ENETS Centre of Excellence, Manchester, UK
| | - W Mansoor
- Department of Medical Oncology, The Christie NHS Foundation Trust and ENETS Centre of Excellence, Manchester, UK
| | - P J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester, UK
- Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - D Darby
- Department of Clinical Biochemistry, Salford Royal Hospital, Salford, UK
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Horvath AR, Bossuyt PMM, Sandberg S, John AS, Monaghan PJ, Verhagen-Kamerbeek WDJ, Lennartz L, Cobbaert CM, Ebert C, Lord SJ. Setting analytical performance specifications based on outcome studies - is it possible? Clin Chem Lab Med 2016; 53:841-8. [PMID: 25996384 DOI: 10.1515/cclm-2015-0214] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/10/2015] [Indexed: 11/15/2022]
Abstract
The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medicine proposed a simplified hierarchy for setting analytical performance specifications (APS). The top two levels of the 1999 Stockholm hierarchy, i.e., evaluation of the effect of analytical performance on clinical outcomes and clinical decisions have been proposed to be replaced by one outcome-based model. This model can be supported by: (1a) direct outcome studies; and (1b) indirect outcome studies investigating the impact of analytical performance of the test on clinical classifications or decisions and thereby on the probability of patient relevant clinical outcomes. This paper reviews the need for outcome-based specifications, the most relevant types of outcomes to be considered, and the challenges and limitations faced when setting outcome-based APS. The methods of Model 1a and b are discussed and examples are provided for how outcome data can be translated to APS using the linked evidence and simulation or decision analytic techniques. Outcome-based APS should primarily reflect the clinical needs of patients; should be tailored to the purpose, role and significance of the test in a well defined clinical pathway; and should be defined at a level that achieves net health benefit for patients at reasonable costs. Whilst it is acknowledged that direct evaluations are difficult and may not be possible for all measurands, all other forms of setting APS should be weighed against that standard, and regarded as approximations. Better definition of the relationship between the analytical performance of tests and health outcomes can be used to set analytical performance criteria that aim to improve the clinical and cost-effectiveness of laboratory tests.
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Krabbe JG, Monaghan PJ, Russell J, de Rijke YB. Analytical evaluation of a second generation assay for chromogranin A; a dual-site study. ACTA ACUST UNITED AC 2016; 54:e139-42. [DOI: 10.1515/cclm-2015-0782] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 08/26/2015] [Indexed: 11/15/2022]
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16
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Adaway JE, Dobson R, Walsh J, Cuthbertson DJ, Monaghan PJ, Trainer PJ, Valle JW, Keevil BG. Serum and plasma 5-hydroxyindoleacetic acid as an alternative to 24-h urine 5-hydroxyindoleacetic acid measurement. Ann Clin Biochem 2015; 53:554-60. [PMID: 26438520 DOI: 10.1177/0004563215613109] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2015] [Indexed: 11/17/2022]
Abstract
BACKGROUND Neuroendocrine tumours are slow growing tumours known to secrete a variety of vasoactive peptides which give rise to symptoms of the carcinoid syndrome. The diagnosis and monitoring of patients with neuroendocrine tumours is undertaken in many centres using 24 h urinary measurement of 5-hydroxyindoleacetic acid. However, 5-hydroxyindoleacetic acid can also be quantified in plasma and serum. METHODS We measured 5-hydroxyindoleacetic acid concentration in 134 paired EDTA plasma and urine samples from 108 patients with known neuroendocrine tumours and 26 healthy volunteers. We also compared 5-hydroxyindoleacetic acid concentrations in paired serum and plasma samples (n = 63), then analysed paired urine and serum samples (n = 97). Furthermore, we examined the impact of renal impairment on serum 5-hydroxyindoleacetic acid by analysing 5-hydroxyindoleacetic acid in patients without neuroendocrine tumours in different stages of chronic kidney disease, as indicated by the estimated glomerular filtration rate. RESULTS Plasma and urine 5-hydroxyindoleacetic acid had very similar diagnostic sensitivities and specificities, with areas under the curve on ROC analysis of 0.917 and 0.920, respectively. Serum and plasma 5-hydroxyindoleacetic acid values showed good correlation but serum results demonstrated a positive bias, indicating the necessity for different serum and plasma reference intervals. There was an inverse correlation between estimated glomerular filtration rate and serum 5-hydroxyindoleacetic acid concentration, with 5-hydroxyindoleacetic acid increasing once the estimated glomerular filtration rate falls below 60 mL/min/1.73 m(2). CONCLUSION The measurement of both serum and plasma 5-hydroxyindoleacetic acid can be used for the diagnosis and monitoring of patients with neuroendocrine tumours. Provided renal function is taken into consideration, either of these tests should be incorporated into standard practice as an alternative assay to urinary 5-hydroxyindoleacetic acid.
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Affiliation(s)
- Joanne E Adaway
- Department of Clinical Biochemistry, University Hospital South Manchester NHS Foundation Trust, Manchester, UK The University of Manchester, Manchester Academic Health Science Centre, University Hospital South Manchester NHS Foundation Trust, Manchester, UK
| | - Rebecca Dobson
- Department of Obesity and Endocrinology, University Hospital Aintree and University of Liverpool, Liverpool, UK
| | - Jennifer Walsh
- Academic Unit of Bone Metabolism, The University of Sheffield, UK
| | - Daniel J Cuthbertson
- Department of Obesity and Endocrinology, University Hospital Aintree and University of Liverpool, Liverpool, UK
| | | | - Peter J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, UK
| | - Juan W Valle
- The University of Manchester, Manchester Academic Health Science Centre, University Hospital South Manchester NHS Foundation Trust, Manchester, UK Department of Medical Oncology, The Christie NHS Foundation Trust, UK
| | - Brian G Keevil
- Department of Clinical Biochemistry, University Hospital South Manchester NHS Foundation Trust, Manchester, UK The University of Manchester, Manchester Academic Health Science Centre, University Hospital South Manchester NHS Foundation Trust, Manchester, UK
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Affiliation(s)
- Phillip J Monaghan
- Department of Clinical Biochemistry (B.G.K.), University Hospital of South Manchester, Manchester M23 9LT, United Kingdom; Medical School (P.M.S.), University of Leeds, Leeds LS2 9NL, United Kingdom; The Christie Pathology Partnership (P.J.M.), Manchester, M20 4BX, UK; Department of Endocrinology (P.J.T.), The Christie NHS Foundation Trust, Manchester M20 4BX, United Kingdom; and Centre for Endocrinology & Diabetes (P.J.T.), Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre, United Kingdom
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Shekhar C, Monaghan PJ, Morris J, Issa B, Whorwell PJ, Keevil B, Houghton LA. Rome III functional constipation and irritable bowel syndrome with constipation are similar disorders within a spectrum of sensitization, regulated by serotonin. Gastroenterology 2013; 145:749-57; quiz e13-4. [PMID: 23872499 DOI: 10.1053/j.gastro.2013.07.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 06/12/2013] [Accepted: 07/10/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Patients with irritable bowel syndrome with constipation (IBS-C) and patients with functional constipation (FC) have similar symptoms, and these disorders overlap in their diagnostic features. Little is known about their overlap in physiology or the involvement of serotonin signaling. We investigated relationships between platelet-depleted plasma concentrations of serotonin, gastrointestinal symptoms, and motor-sensory function in patients with FC or IBS-C compared with healthy volunteers (controls). METHODS We measured platelet-depleted plasma concentrations of serotonin in fasting and fed individuals with IBS-C (n = 23; 19-50 years old), FC (n = 11; 25-46 years old), and controls (n = 23; 20-49 years old) recruited in Manchester, UK. We also quantified abdominal and bowel-related symptoms, rectal sensitivity, oro-cecal transit, and colonic (whole intestine) transit. RESULTS Patients with IBS-C or FC had similar baseline symptoms, bowel habits, oro-cecal and colonic transit, and fasting concentrations of serotonin and response to meal ingestion. Only patients with IBS-C had increased symptoms after ingestion of a meal (P < .001)-these patients tended to have lower sensory thresholds than patients with FC. Defecation frequency in the combined group of patients with IBS-C or FC correlated inversely with serotonin concentration (r = -0.4; P = .03). Serotonin concentration also correlated with pain threshold (r = 0.4; P = .02) and stool threshold (r = 0.5; P = .06), which correlated inversely with defecation frequency (r = -0.3; P = .10). CONCLUSIONS FC and IBS-C, based on Rome III criteria, are not distinct disorders, symptomatically or physiologically. Instead, they appear to lie in a spectrum of visceral sensitivity modulated by serotonin signaling. Symptom response to meal ingestion should be considered in patient classification.
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Affiliation(s)
- Chander Shekhar
- Neurogastroenterology Unit, University of Manchester, Manchester, UK
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19
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Horvath AR, Lord SJ, StJohn A, Sandberg S, Cobbaert CM, Lorenz S, Monaghan PJ, Verhagen-Kamerbeek WDJ, Ebert C, Bossuyt PMM. From biomarkers to medical tests: the changing landscape of test evaluation. Clin Chim Acta 2013; 427:49-57. [PMID: 24076255 DOI: 10.1016/j.cca.2013.09.018] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 09/15/2013] [Accepted: 09/15/2013] [Indexed: 01/14/2023]
Abstract
Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver patient benefits to justify their use in clinical practice. Laboratory professionals need to be familiar with these evidence requirements to better engage in biomarker research and decisions about their appropriate use. This paper by a multidisciplinary group of the European Federation of Clinical Chemistry and Laboratory Medicine describes the pathway of a laboratory assay measuring a biomarker to becoming a medically useful test. We define the key terms, principles and components of the test evaluation process. Unlike previously described linearly staged models, we illustrate how the essential components of analytical and clinical performances, clinical and cost-effectiveness and the broader impact of testing assemble in a dynamic cycle. We highlight the importance of defining clinical goals and how the intended application of the biomarker in the clinical pathway should drive each component of test evaluation. This approach emphasizes the interaction of the different components, and that clinical effectiveness data should be fed back to refine analytical and clinical performances to achieve improved outcomes. The framework aims to support the understanding of key stakeholders. The laboratory profession needs to strengthen collaboration with industry and experts in evidence-based medicine, regulatory bodies and policy makers for better decisions about the use of new and existing medical tests.
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Affiliation(s)
- Andrea R Horvath
- SEALS Department of Clinical Chemistry, Prince of Wales Hospital and School of Medical Sciences, University of New South Wales, Australia; Screening and Test Evaluation Program, School of Public Health, University of Sydney, Australia.
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20
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Abstract
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.
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Affiliation(s)
- Phillip J Monaghan
- Department of Clinical Biochemistry, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, UK
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21
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Affiliation(s)
- Phillip J Monaghan
- Department of Clinical Biochemistry, The Christie NHS Foundation Trust, Manchester, UK
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Monaghan PJ, Owen LJ, Trainer PJ, Brabant G, Keevil BG, Darby D. Response to ‘Comparison of serum cortisol measurement by immunoassay and liquid chromatography-tandem mass spectrometry in patients receiving the 11β-hydroxylase inhibitor metyrapone’ by Halsall et al. Ann Clin Biochem 2012. [DOI: 10.1258/acb.2011.011217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Phillip J Monaghan
- Department of Biochemistry, The Christie NHS Foundation Trust, Manchester M20 4BX
| | - Laura J Owen
- Department of Biochemistry, University Hospital of South Manchester, Manchester M23 9LT
| | - Peter J Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester M20 4BX, UK
| | - Georg Brabant
- Department of Endocrinology, The Christie NHS Foundation Trust, Manchester M20 4BX, UK
| | - Brian G Keevil
- Department of Biochemistry, University Hospital of South Manchester, Manchester M23 9LT
| | - Denise Darby
- Department of Biochemistry, The Christie NHS Foundation Trust, Manchester M20 4BX
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Darby D, So J, Russell J, Monaghan PJ. Spuriously raised serum creatinine associated with an excipient present in an intravenous dexamethasone formulation. Ann Clin Biochem 2012; 49:292-4. [PMID: 22349552 DOI: 10.1258/acb.2011.011114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although the active pharmaceutical ingredient remains constant, the excipients used will vary according to the manufacturer. This case report is of spuriously raised serum creatinine due to an excipient in one particular intravenous dexamethasone formulation. A patient had three serum creatinine measurements of 102, 369 and 91 μmol/L over a four-hour period. The second result was believed to be spurious and appropriate investigations were instigated. The patient had received dexamethasone intravenously between the first and second blood samples. This was administered as a bolus via a cannula in the dorsum of the hand, and the blood sample was taken by venepuncture of the antecubital fossa of the same arm approximately five minutes later. The dexamethasone used (Hospira UK Ltd) contained creatinine at a concentration of 70,720 μmol/L, with a total of 170 μmol of creatinine given to the patient. Assuming a volume of distribution of 40 L in a 70-kg man, an increase in serum creatinine of 4-5 μmol/L would be expected once equilibrated. It is thought that the serum creatinine result observed was a consequence of the creatinine excipient in the dexamethasone not having completely distributed throughout the body and still being at relatively high concentrations within the limb into which it had been administered. Intravenous dexamethasone can lead to spurious creatinine results, not due to analytical interference but rather the analytically correct measurement of creatinine added as an excipient. This case clearly demonstrates the impact preanalytical factors can have on the accuracy of results.
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Affiliation(s)
- Denise Darby
- Department of Clinical Biochemistry, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, UK.
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Monaghan PJ, Brown HA, Houghton LA, Keevil BG. Measurement of serotonin in platelet depleted plasma by liquid chromatography tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:2163-7. [DOI: 10.1016/j.jchromb.2009.05.045] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 05/13/2009] [Accepted: 05/21/2009] [Indexed: 10/20/2022]
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Monaghan PJ, Leonard MB, Neithercut WD, Raraty MGT, Sodi R. False positive carbohydrate antigen 19-9 (CA19-9) results due to a low-molecular weight interference in an apparently healthy male. Clin Chim Acta 2009; 406:41-4. [PMID: 19463797 DOI: 10.1016/j.cca.2009.05.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 05/08/2009] [Accepted: 05/08/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND We investigated the presence of interference in a patient who had an elevated CA19-9 concentration using the ADVIA Centaur but results within reference limits with ROCHE Modular Analytics E170 and Brahms KRYPTOR analysers. METHODS We performed repeat analyses using the same (ADVIA Centaur) and alternate immunossays (Roche Modular Analytics E170 and Brahms KRYPTOR) on the patient's sample and investigated for known interferences. To determine the nature of the interference, we measured CA19-9 on the ADVIA Centaur after dilution experiments and after incubation with non-immune animal sera and in heterophilic blocking tubes (HBT). We also undertook polyethylene glycol precipitation, lectin inhibition experiments and gel filtration chromatography. RESULTS A curvilinear response to dilution was observed with the ADVIA Centaur. Other known interferences were excluded. Treatment with HBT or non-immune animal sera did not give clinically different results from untreated samples. There was only 0.59% recovery after PEG precipitation in the sample from the case patient. Lectin reduced the assay signal in four patient samples (recovery=1.9-14.1%) but not in the case patient (recovery=106.2%). Gel filtration studies suggested the presence of a low molecular weight (approximately 100 kDa) interference in the case patient's serum. CONCLUSIONS We report a novel mode of interference and show a non-CA19-9, low molecular-weight interference affecting the ADVIA Centaur CA19-9 immunoassay.
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Affiliation(s)
- P J Monaghan
- Department of Clinical Biochemistry, Wirral University Teaching Hospital, Arrowe Park Road, Upton, Wirral, CH49 5PE, UK
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Hay S, Pang J, Monaghan PJ, Wang X, Evans RM, Sutcliffe MJ, Allemann RK, Scrutton NS. Secondary kinetic isotope effects as probes of environmentally-coupled enzymatic hydrogen tunneling reactions. Chemphyschem 2008; 9:1536-9. [PMID: 18613201 DOI: 10.1002/cphc.200800291] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sam Hay
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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Monaghan PJ, Leys D, Scrutton NS. Mechanistic aspects and redox properties of hyperthermophilic L-proline dehydrogenase from Pyrococcus furiosus related to dimethylglycine dehydrogenase/oxidase. FEBS J 2007; 274:2070-87. [PMID: 17371548 DOI: 10.1111/j.1742-4658.2007.05750.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Two ORFs encoding a protein related to bacterial dimethylglycine oxidase were cloned from Pyrococcus furiosus DSM 3638. The protein was expressed in Escherichia coli, purified, and shown to be a flavoprotein amine dehydrogenase. The enzyme oxidizes the secondary amines L-proline, L-pipecolic acid and sarcosine, with optimal catalytic activity towards L-proline. The holoenzyme contains one FAD, FMN and ATP per alphabeta complex, is not reduced by sulfite, and reoxidizes slowly following reduction, which is typical of flavoprotein dehydrogenases. Isolation of the enzyme in a form containing only FAD cofactor allowed detailed pH dependence studies of the reaction with L-proline, for which a bell-shaped dependence (pK(a) values 7.0 +/- 0.2 and 7.6 +/- 0.2) for k(cat)/K(m) as a function of pH was observed. The pH dependence of k(cat) is sigmoidal, described by a single macroscopic pK(a) of 7.7 +/- 0.1, tentatively attributed to ionization of L-proline in the Michaelis complex. The preliminary crystal structure of the enzyme revealed active site residues conserved in related amine dehydrogenases and potentially implicated in catalysis. Studies with H225A, H225Q and Y251F mutants ruled out participation of these residues in a carbanion-type mechanism. The midpoint potential of enzyme-bound FAD has a linear temperature dependence (- 3.1 +/- 0.05 mV x C degrees (-1)), and extrapolation to physiologic growth temperature for P. furiosus (100 degrees C) yields a value of - 407 +/- 5 mV for the two-electron reduction of enzyme-bound FAD. These studies provide the first detailed account of the kinetic/redox properties of this hyperthermophilic L-proline dehydrogenase. Implications for its mechanism of action are discussed.
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Affiliation(s)
- Phillip J Monaghan
- Manchester Interdisciplinary Biocentre and Faculty of Life Sciences, University of Manchester, UK
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Monaghan PJ, Leys D, Scrutton NS. Crystallization and preliminary X-ray diffraction analysis of a flavoenzyme amine dehydrogenase/oxidase from Pyrococcus furiosus DSM 3638. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:756-8. [PMID: 16511149 PMCID: PMC1952344 DOI: 10.1107/s1744309105020737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 06/29/2005] [Indexed: 11/10/2022]
Abstract
A flavoprotein amine dehydrogenase/oxidase with subunit molecular weights of 54.8 kDa (alpha-subunit) and 42.4 kDa (beta-subunit) and specificity for L-proline was cloned from the genomic DNA of the hyperthermophilic marine archaeon Pyrococcus furiosus DSM 3638. The enzyme was overexpressed in Escherichia coli and purified to homogeneity. The enzyme was crystallized using the sitting-drop vapour-diffusion technique. Diffraction data from two different crystal forms were collected to 3.3 and 3.6 A, respectively, using synchrotron radiation. Both crystals belonged to space group P1, with unit-cell parameters a = 91.3, b = 136.3, c = 203.8 A, alpha = 94.5, beta = 99.4, gamma = 102.7 degrees and a = 93.7, b = 116.3, c = 126.9 A, alpha = 97.3, beta = 99.9, gamma = 104.6 degrees.
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Affiliation(s)
- Phillip J. Monaghan
- Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, England
| | - David Leys
- Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, England
| | - Nigel S. Scrutton
- Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, England
- Correspondence e-mail:
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