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White CA, Gaynor-Sodeifi K, Norman PA, Furman M, Sochett E. Accuracy of Shorter Iohexol GFR Measurement Protocols in Individuals with Preserved Kidney Function. KIDNEY360 2024; 5:1178-1185. [PMID: 39008636 PMCID: PMC11371346 DOI: 10.34067/kid.0000000000000511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 07/08/2024] [Indexed: 07/17/2024]
Abstract
Key Points Shorter measured GFR protocols are accurate and precise compared with the reference standard measured GFR protocol in patients with preserved GFR. These shorter protocols can potentially improve the adoption of GFR measurement more widely by reducing procedural time and cost. Background Measured GFR (mGFR) using exogenous tracers is recommended in a number of settings. Plasma one-compartment multisample protocols (MSPs) are the most commonly used, with iohexol being the dominant tracer. The accuracy of MSPs has mostly been evaluated in the setting of reduced GFR where delayed initial and final samples are recommended. Much less is known about MSPs when GFR is not decreased, and the default protocol tends to include initial sampling at 120 minutes and final sampling at 240 minutes after iohexol injection. The recent Kidney Disease Improving Global Outcomes 2024 Clinical Practice Guideline for the Evaluation and Management of CKD includes research recommendations for the development of shorter more efficient mGFR protocols. The objective of this study was to assess the performance of shorter MSPs with earlier initial (60 and 90 minutes) and final (150, 180, and 210 minutes) sampling times in individuals with preserved GFR. Reference mGFR (R-mGFR) was calculated using five samples collected between 120 and 240 minutes. Methods Four different combinations of shorter sampling strategies were investigated. Performance was evaluated using measurements of bias, precision, and accuracy (P2, P5, and mean absolute error). Results The mean R-mGFR of the 43 participants was 102.3±13.7 ml/min per 1.73 m2. All shorter mGFRs had biases <1 ml/min per 1.73 m2 and mean absolute error <1.6 ml/min per 1.73 m2. All shorter mGFRs were within 5% of the R-mGFR, and the majority were within 2%. Conclusions These results demonstrate that shortening the mGFR procedure in individuals with preserved GFR provides similar results to the current standard while significantly decreasing procedure time.
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Affiliation(s)
- Christine A. White
- Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Kaveh Gaynor-Sodeifi
- Division of Endocrinology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Patrick A. Norman
- Kingston Health Science Centre, Kingston General Health Research Institute, Kingston, Ontario, Canada
| | - Michelle Furman
- Division of Endocrinology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Etienne Sochett
- Division of Endocrinology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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Trevisani F, Simeoni M, Bettiga A, Cinque A, Floris M. Measurement of Glomerular Filtration Rate in Patients Undergoing Renal Surgery for Cancer: Estimated Glomerular Filtration Rate versus Measured Glomerular Filtration Rate in the Era of Precision Medicine. Kidney Blood Press Res 2024; 49:336-344. [PMID: 38636485 DOI: 10.1159/000538854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Accepted: 03/20/2024] [Indexed: 04/20/2024] Open
Abstract
BACKGROUND In the era of precision medicine, determining reliable renal function assessment remains a critical and debatable issue, especially in nephrology and oncology. SUMMARY This paper delves into the significance of accurately measured glomerular filtration rate (mGFR) in clinical practice, highlighting its essential role in guiding medical decisions and managing kidney health, particularly in the context of renal cancer (RC) patients undergoing nephrotoxic anti-cancer drugs. The limitations and advantages of traditional glomerular filtration rate (GFR) estimation methods, primarily using serum biomarkers like creatinine and cystatin C, are discussed, emphasizing their possible inadequacy in cancer patients. Specifically, newer formulae designed for GFR estimation in cancer patients may not perform at best in RC patients. The paper explores various methods for direct GFR measurement, including the gold standard inulin clearance and alternatives like iohexol plasma clearance. KEY MESSAGE Despite the logistical challenges of these methods, their implementation is crucial for accurate renal function assessment. The paper concludes by emphasizing the need for continued research and innovation in GFR measurement methodologies to improve patient outcomes, particularly in populations with complex medical needs.
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Affiliation(s)
- Francesco Trevisani
- Urological Research Institute (URI), Division of Experimental Oncology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Unit of Urology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Biorek srl, San Raffaele Scientific Institute, Milan, Italy
| | - Mariadelina Simeoni
- Department of Translational Medical Sciences University of Campania "Luigi Vanvitelli, Naples, Italy
| | - Arianna Bettiga
- Unit of Urology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Matteo Floris
- Department of Nephrology, Dialysis, and Transplantation, ARNAS G. Brotzu, Cagliari, Italy
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Jin Z, Bertholf RL, Yi X. Assessment of Iohexol Serum Clearance by LC-MS/MS with Isotopically Labeled Internal Standard. Methods Mol Biol 2024; 2737:319-327. [PMID: 38036833 DOI: 10.1007/978-1-0716-3541-4_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Accurate measurement of the glomerular filtration rate (GFR) is essential for detecting renal insufficiency in living kidney donors. Iohexol is a "near-ideal" exogenous filtration marker for GFR measurement that has attracted increasing interest in clinical practice because it is non-toxic, non-radioactive, readily available, and easy to measure. In this chapter, we describe a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to measure iohexol in serum and to calculate GFR based on the rate of iohexol clearance. In this procedure, the contrast agent iohexol is administrated to the study subject in an outpatient setting, and three timed blood samples are collected. The serum proteins are precipitated, and the supernatant containing iohexol and the internal standard 2H5-iohexol is diluted prior to LC-MS/MS analysis. The LC-MS/MS method utilizes a Thermo Vanquish UHPLC coupled with TSQ Endura triple quadruple mass spectrometer, with a total run time of 2.5 min. The LC-MS/MS method has demonstrated good analytical performances, and the workflow can be used to reliably measure GFR in apparently healthy individuals without impaired renal function, such as living kidney donors.
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Affiliation(s)
- Zhicheng Jin
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Roger L Bertholf
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Xin Yi
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, USA.
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA.
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Jin Z, Huang R, Christensen P, Bertholf RL, Yi X. Accuracy-Based Glomerular Filtration Rate Assessment by Plasma Iohexol Clearance in Kidney Transplant Donors. J Clin Med 2023; 12:6054. [PMID: 37762993 PMCID: PMC10532236 DOI: 10.3390/jcm12186054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
BACKGROUND An accurate measurement of the glomerular filtration rate (GFR) is essential for detecting renal insufficiency in living kidney donors. Iohexol is a "near-ideal" exogenous filtration marker for GFR measurements that has attracted increasing interest in clinical practice because it is non-toxic, non-radioactive, readily available, and easy to measure. In this study, we aimed to set up a laboratory test to conveniently assess the plasma clearance of iohexol in living kidney donors. METHODS A workflow was established in the institution's infusion clinic to administer iohexol and to collect three timed blood samples from renal transplant donors. Iohexol was thereafter measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The serum proteins were precipitated and the supernatant containing iohexol was diluted prior to the LC-MS/MS analysis. The LC-MS/MS method was developed on a Thermo Vanquish UHPLC coupled with a TSQ Endura triple quadruple mass spectrometer with a total run time of 2.5 min. The analytical performance of the method was assessed. RESULTS The LC-MS/MS method demonstrated a good analytical performance. To calculate the iohexol clearance rate and the GFR, automated data integration and a result calculation were accomplished by using a custom Python script. Automated result reporting was achieved using a laboratory informatics system (LIS) vendor's direct media interface. CONCLUSIONS We developed and implemented a laboratory test to assess the plasma clearance of iohexol. A workflow was established in the hospital to reliably measure the GFR in living kidney donors, with a potential to be further expanded into other areas where an accurate GFR measurement is needed.
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Affiliation(s)
- Zhicheng Jin
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Rongrong Huang
- Department of Pathology and Immunology, Baylor College of Medicine, Harris Health System Ben Taub Hospital, Houston, TX 77030, USA
| | - Paul Christensen
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Roger L. Bertholf
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Xin Yi
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
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Turner ME, Paynter AS, White CA, Mazzetti T, Ward EC, Norman PA, Munroe J, Adams MA, Holden RM. Sex Differences in Phosphate Homeostasis: Females Excrete More Phosphate and Calcium After an Oral Phosphate Challenge. J Clin Endocrinol Metab 2023; 108:909-919. [PMID: 36268820 DOI: 10.1210/clinem/dgac616] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/14/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT Dietary consumption of phosphate is increasing, and elevated serum phosphate is associated with increased cardiovascular disease (CVD) risk. Sex differences in phosphate homeostasis and response to changes in dietary phosphate intake, which are not captured by clinically measured analytes, may contribute to differences in CVD presentation and bone disease. OBJECTIVE To assess sex differences in acute phosphate homeostasis in response to a single oral phosphate challenge. DESIGN Cross-sectional. SETTING General community. PARTICIPANTS 78 participants (40-76 years) with measured glomerular filtration rate >60 mL/min/1.73 m2 and no clinically diagnosed CVD and 14 young healthy adults. MAIN OUTCOME MEASURES To elucidate subtle alterations in phosphate homeostasis, we employ an acute challenge whereby the hormonal response, circulating mineral levels, and urinary excretion are assessed following an oral challenge of phosphate. RESULTS Although both males and females had similar changes in circulating phosphate, calcium, and parathyroid hormone in response to the challenge, females excreted ∼1.9x more phosphate and ∼2.7x more calcium than males, despite not consuming calcium. These sex differences were recapitulated in healthy young adults. This excretion response did not correlate to age, serum phosphate, or estradiol levels. The females with greater excretion of phosphate had higher levels of bone resorption markers compared to formation markers. CONCLUSIONS Taken together, these data identify sex differences in acute phosphate homeostasis, specifically that females may mobilize and excrete endogenous sources of calcium and phosphate in response to oral phosphate compared to males. While high levels of dietary phosphate negatively impact bone, our results suggest that females may incur more risk from these diets.
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Affiliation(s)
- Mandy E Turner
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L3N6, Canada
| | - Amanda S Paynter
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L3N6, Canada
| | - Christine A White
- Department of Medicine, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Tom Mazzetti
- Department of Medicine, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Emilie C Ward
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L3N6, Canada
| | - Patrick A Norman
- KGH Research Institute, Kingston Health Sciences Centre, Kingston, ON K7L2V7, Canada
| | - Jenny Munroe
- Clinical Nutrition, Kingston Health Sciences Center, Kingston, ON K7L 2V7, Canada
| | - Michael A Adams
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L3N6, Canada
| | - Rachel M Holden
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L3N6, Canada
- Department of Medicine, Queen's University, Kingston, ON K7L 3N6, Canada
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Olausson M, Antony D, Johansson M, Travnikova G, Nayakawde NB, Banerjee D, Mackay Søfteland J, Ognissanti D, Andresen Bergström M, Hammarsten O, Premaratne GU. Long-term Transplant Function After Thrombolytic Treatment Ex Vivo of Donated Kidneys Retrieved 4 to 5 H After Circulatory Death. Transplantation 2022; 106:2348-2359. [PMID: 35831928 PMCID: PMC9698194 DOI: 10.1097/tp.0000000000004235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/29/2022] [Accepted: 05/18/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND Using a novel thrombolytic technique, we present long-term transplant function, measured by creatinine and iohexol clearance, after utilizing kidneys from porcine donors with uncontrolled donation after circulatory deaths, with 4.5-5 h of warm ischemia. METHODS Pigs in the study group were subjected to simulated circulatory death. After 2 h, ice slush was inserted into the abdomen and 4.5 h after death, the kidneys were retrieved. Lys-plasminogen, antithrombin-III, and alteplase were injected through the renal arteries on the back table. Subsequent ex vivo perfusion was continued for 3 h at 15°C, followed by 3 h with red blood cells at 32°C, and then transplanted into pigs as an autologous graft as only renal support. Living-donor recipient pigs that did not receive ex vivo perfusion, and unilateral nephrectomized pigs served as the controls. RESULTS Pigs in the study group (n = 13), surviving 10 d or more were included, of which 7 survived for 3 mo. Four animals in the living-donor group (n = 6) and all 5 nephrectomized animals survived for 3 mo. Creatinine levels in the plasma and urine, neutrophil gelatinase-associated lipocalin levels, Kidney Injury Marker-1 expression, and iohexol clearance at 3 mo did not differ significantly between the study and living-donor groups. Histology and transmission electron microscopy after 3 mo showed negligible fibrosis and no other damage. CONCLUSIONS The present method salvages kidneys from extended unontrolled donation after circulatory death using thrombolytic treatment while preserving histology and enabling transplantation after ex vivo reconditioning, with clinically acceptable late function after 3 mo, as measured by creatinine and iohexol clearance.
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Affiliation(s)
- Michael Olausson
- Department of Transplantation, Sahlgrenska Academy, Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Deepti Antony
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Martin Johansson
- Department of Laboratory Medicine, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
| | - Galina Travnikova
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Nikhil B. Nayakawde
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Debashish Banerjee
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - John Mackay Søfteland
- Department of Transplantation, Sahlgrenska Academy, Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Damiano Ognissanti
- Department of Mathematic, Chalmers University of Technology and Gothenburg University, Gothenburg, Sweden
| | - Moa Andresen Bergström
- Department of Laboratory Medicine, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
- Department of Clinical Chemistry, Laboratory of Clinical Chemistry, Sahlgrenska University Hospital, SE-41345 Gothenburg, Sweden
| | - Ola Hammarsten
- Department of Laboratory Medicine, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
- Department of Clinical Chemistry, Laboratory of Clinical Chemistry, Sahlgrenska University Hospital, SE-41345 Gothenburg, Sweden
| | - Goditha U. Premaratne
- Department of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy at Gothenburg University and the Sahlgrenska Transplant Institute at Sahlgrenska University Hospital, Gothenburg, Sweden
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7
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Fabian J, Kalyesubula R, Mkandawire J, Hansen CH, Nitsch D, Musenge E, Nakanga WP, Prynn JE, Dreyer G, Snyman T, Ssebunnya B, Ramsay M, Smeeth L, Tollman S, Naicker S, Crampin A, Newton R, George JA, Tomlinson L. Measurement of kidney function in Malawi, South Africa, and Uganda: a multicentre cohort study. Lancet Glob Health 2022; 10:e1159-e1169. [PMID: 35839814 DOI: 10.1016/s2214-109x(22)00239-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 04/13/2022] [Accepted: 05/11/2022] [Indexed: 12/18/2022]
Abstract
BACKGROUND The burden of kidney disease in many African countries is unknown. Equations used to estimate kidney function from serum creatinine have limited regional validation. We sought to determine the most accurate way to measure kidney function and thus estimate the prevalence of impaired kidney function in African populations. METHODS We measured serum creatinine, cystatin C, and glomerular filtration rate (GFR) using the slope-intercept method for iohexol plasma clearance (mGFR) in population cohorts from Malawi, Uganda, and South Africa. We compared performance of creatinine and cystatin C-based estimating equations to mGFR, modelled and validated a new creatinine-based equation, and developed a multiple imputation model trained on the mGFR sample using age, sex, and creatinine as the variables to predict the population prevalence of impaired kidney function in west, east, and southern Africa. FINDINGS Of 3025 people who underwent measured GFR testing (Malawi n=1020, South Africa n=986, and Uganda n=1019), we analysed data for 2578 participants who had complete data and adequate quality measurements. Among 2578 included participants, creatinine-based equations overestimated kidney function compared with mGFR, worsened by use of ethnicity coefficients. The greatest bias occurred at low kidney function, such that the proportion with GFR of less than 60 mL/min per 1·73 m2 either directly measured or estimated by cystatin C was more than double that estimated from creatinine. A new creatinine-based equation did not outperform existing equations, and no equation, including the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 race-neutral equation, estimated GFR within plus or minus 30% of mGFR for 75% or more of the participants. Using a model to impute kidney function based on mGFR, the estimated prevalence of impaired kidney function was more than two-times higher than creatinine-based estimates in populations across six countries in Africa. INTERPRETATION Estimating GFR using serum creatinine substantially underestimates the individual and population-level burden of impaired kidney function in Africa with implications for understanding disease progression and complications, clinical care, and service provision. Scalable and affordable ways to accurately identify impaired kidney function in Africa are urgently needed. FUNDING The GSK Africa Non-Communicable Disease Open Lab. TRANSLATIONS For the Luganda, Chichewa and Xitsonga translations of the abstract see Supplementary Materials section.
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Affiliation(s)
- June Fabian
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Wits Donald Gordon Medical Centre, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Robert Kalyesubula
- MRC/UVRI & London School of Hygiene and Tropical Medicine Research Unit, Entebbe, Uganda; Department of Non-Communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Joseph Mkandawire
- Department of Non-Communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK; Department of Surgery, Pan-African Academy of Christian Surgeons, Malamulo, Thyolo, Malawi; Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi
| | - Christian Holm Hansen
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Dorothea Nitsch
- Department of Non-Communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Eustasius Musenge
- Division of Biostatistics and Epidemiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Wisdom P Nakanga
- MRC/UVRI & London School of Hygiene and Tropical Medicine Research Unit, Entebbe, Uganda; Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi
| | - Josephine E Prynn
- Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi; Institute of Cardiovascular Science, University College London, London, UK
| | - Gavin Dreyer
- Department of Nephrology, Barts Health National Health Service Trust, London, UK
| | - Tracy Snyman
- Department of Chemical Pathology, National Health Laboratory Service, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Billy Ssebunnya
- MRC/UVRI & London School of Hygiene and Tropical Medicine Research Unit, Entebbe, Uganda
| | - Michele Ramsay
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Liam Smeeth
- Department of Non-Communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Stephen Tollman
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; International Network for the Demographic Evaluation of Populations and their Health Network, Accra, Ghana
| | - Saraladevi Naicker
- Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Amelia Crampin
- Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi
| | - Robert Newton
- MRC/UVRI & London School of Hygiene and Tropical Medicine Research Unit, Entebbe, Uganda; Department of Health Sciences, University of York, York, UK
| | - Jaya A George
- Department of Chemical Pathology, National Health Laboratory Service, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Laurie Tomlinson
- Department of Non-Communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
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Ognissanti D, Andresen Bergström M, Theodorsson E, Larsson A, Nordin G, Hammarsten O. Estimating Analytical Errors of Glomerular Filtration Rate Measurement. Clin Chem 2022; 68:1211-1218. [PMID: 35802029 DOI: 10.1093/clinchem/hvac098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/11/2022] [Indexed: 11/14/2022]
Abstract
BACKGROUND Few studies are available on how to optimize time points for sampling and how to estimate effects of analytical uncertainty when glomerular filtration rate (GFR) is calculated. METHODS We explored the underlying regression mathematics of how analytical variation of a kidney filtration marker affects 1-compartment, slope-and-intercept GFR calculations, using 2 or 3 time points following a bolus injection, and used this to examine the results from 731 routine 3-point iohexol plasma clearance measurements. RESULTS GFR calculations inflated analytical uncertainty if the time points were taken too late after the bolus injection and too close after each other. The uncertainty in GFR calculation was, however, the same as the analytical uncertainty if optimal time points were used. The middle of the 3 samples was of little value. The first sample should be taken as early as possible after the distribution phase. Sampling before the patient specific half-life of the kidney filtration marker resulted in an exponential error inflation whereas no error inflation was seen when sampling occurred later than 2 half-lives. Theoretical GFR uncertainty could be lowered 2.6-fold if individually optimized time points for sampling had been used in our 731 clearance measurements. Using Taylor expansions to approximate the moments of transformed random variables, the uncertainty of an individual GFR measurement could be calculated in a simple enough way to be applicable by laboratory software. CONCLUSIONS We provide a theoretical foundation to select patient-optimal time points that may both limit errors and allow calculation of GFR uncertainty.
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Affiliation(s)
- Damiano Ognissanti
- Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden
| | - Moa Andresen Bergström
- Department of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden.,Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Elvar Theodorsson
- Division of Clinical Chemistry, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Anders Larsson
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden
| | - Gunnar Nordin
- External Quality Assurance in Laboratory Medicine in Sweden (EQUALIS), Uppsala, Sweden
| | - Ola Hammarsten
- Department of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden.,Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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9
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Gaebe K, White CA, Mahmud FH, Scholey JW, Elia YT, Sochett EB, Cherney DZ. Evaluation of novel glomerular filtration rate estimation equations in adolescents and young adults with type 1 diabetes. J Diabetes Complications 2022; 36:108081. [PMID: 34756765 DOI: 10.1016/j.jdiacomp.2021.108081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/12/2021] [Accepted: 10/21/2021] [Indexed: 12/25/2022]
Abstract
AIMS Individuals with type 1 diabetes (T1D) are at an increased risk of chronic kidney disease making estimation of glomerular filtration rate (eGFR) an important component of diabetes care. Which eGFR equation is most appropriate to use in patients with T1D during the transition to adult care is unclear. We, therefore, sought to evaluate the performance of five eGFR equations in adolescents and young adults with T1D. METHODS Measured iohexol-based glomerular filtration rate was compared to the Chronic Kidney Disease and Epidemiology Collaboration (CKD-EPI) eGFR, Chronic Kidney Disease in Children (CKiD) eGFR, and three recently developed age-adjusted versions of these in 53 patients with T1D and preserved GFR using bias, precision, and accuracy. RESULTS The best performance was found in the sex-dependent CKiD equation (bias: -0.8, accuracy: 11.8 ml/min/1.73 m2). Bias and accuracy (26.4 and 26.8 ml/min/1.73 m2) were worst in the CKD-EPI equation. Age-dependent adjustment improved performance for this equation (bias: 5.3, accuracy: 13.4 ml/min/1.73 m2), but not for the CKiD equation (bias: 15.5, accuracy: 18.8 ml/min/1.73 m2). CONCLUSION Age-adjustment improved performance for the CKD-EPI equation, but not for the CKiD equation. The sex-adjusted CKiD equation performed best out of all equations.
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Affiliation(s)
- Karolina Gaebe
- Division of Endocrinology and Metabolism, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
| | - Christine A White
- Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Farid H Mahmud
- Division of Endocrinology and Metabolism, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - James W Scholey
- Division of Nephrology, Department of Medicine, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Yesmino T Elia
- Division of Endocrinology and Metabolism, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Etienne B Sochett
- Division of Endocrinology and Metabolism, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - David Z Cherney
- Division of Nephrology, Department of Medicine, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
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10
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Currin S, Gondwe M, Mayindi N, Chipungu S, Khoza B, Khambule L, Snyman T, Tollman S, Fabian J, George J. Evaluating chronic kidney disease in rural South Africa: comparing estimated glomerular filtration rate using point-of-care creatinine to iohexol measured GFR. Clin Chem Lab Med 2021; 59:1409-1420. [PMID: 33711217 DOI: 10.1515/cclm-2020-1882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/03/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES The prevalence of chronic kidney disease is rising rapidly in low- and middle-income countries. Serum creatinine and estimation of glomerular filtration rate (GFR) are critical diagnostic tools, yet access to centralised laboratory services remains limited in primary care resource-limited settings. The aim of this study was to evaluate point-of-care (POC) technologies for serum creatinine measurement and to compare their performance to a gold standard measurement using iohexol measured GFR (mGFR). METHODS POC creatinine was measured using iSTAT® and StatSensor® devices in capillary and venous whole blood, and laboratory creatinine was measured using the compensated kinetic Jaffe method in 670 participants from a rural area in South Africa. GFR estimating equations Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease (CKD-EPI and MDRD) for POC and laboratory creatinine were compared to iohexol mGFR. RESULTS Calculated GFR for laboratory and POC creatinine measurements overestimated GFR (positive bias of 1.9-34.1 mL/min/1.73 m2). However, all POC devices had less positive bias than the laboratory Jaffe method (1.9-14.7 vs. 34.1 for MDRD, and 8.4-19.9 vs. 28.6 for CKD-EPI). Accuracy within 30% of mGFR ranged from 0.56 to 0.72 for POC devices and from 0.36 to 0.43 for the laboratory Jaffe method. POC devices showed wider imprecision with coefficients of variation ranging from 4.6 to 10.2% compared to 3.5% for the laboratory Jaffe method. CONCLUSIONS POC estimated GFR (eGFR) showed improved performance over laboratory Jaffe eGFR, however POC devices suffered from imprecision and large bias. The laboratory Jaffe method performed poorly, highlighting the need for laboratories to move to enzymatic methods to measure creatinine.
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Affiliation(s)
- Sean Currin
- Department of Chemical Pathology, University of Witwatersrand, Johannesburg, South Africa
- Department of Chemical Pathology, National Health Laboratory Service, Johannesburg, South Africa
| | - Mwawi Gondwe
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Nokthula Mayindi
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Shingirai Chipungu
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Bongekile Khoza
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Lungile Khambule
- Department of Chemical Pathology, University of Witwatersrand, Johannesburg, South Africa
| | - Tracy Snyman
- Department of Chemical Pathology, University of Witwatersrand, Johannesburg, South Africa
- Department of Chemical Pathology, National Health Laboratory Service, Johannesburg, South Africa
| | - Stephen Tollman
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- International Network for the Demographic Evaluation of Populations and their Health (INDEPTH) Network, Accra, Ghana
| | - June Fabian
- Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- Wits Donald Gordon Medical Centre, School of Clinical Medicine, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Jaya George
- Department of Chemical Pathology, University of Witwatersrand, Johannesburg, South Africa
- Department of Chemical Pathology, National Health Laboratory Service, Johannesburg, South Africa
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11
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Dhondt L, Croubels S, De Cock P, Dhont E, De Baere S, De Paepe P, Devreese M. Volumetric absorptive microsampling as alternative sampling technique for renal function assessment in the paediatric population using iohexol. J Chromatogr B Analyt Technol Biomed Life Sci 2021; 1171:122623. [PMID: 33735803 DOI: 10.1016/j.jchromb.2021.122623] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 02/07/2021] [Accepted: 02/20/2021] [Indexed: 10/22/2022]
Abstract
The glomerular filtration rate (GFR) is considered the best overall index for the renal function. Currently, one of the most promising exogenous markers for GFR assessment is iohexol. In this study, the suitability of volumetric absorptive microsampling (VAMS) as alternative for the conventional blood sampling and quantification of iohexol in paediatric plasma was assessed. Therefore, a new, fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed. Subsequently, the clinical suitability was evaluated in 20 paediatric patients by comparing plasma iohexol concentrations and associated GFR values obtained by the VAMS method with those obtained by conventional blood sampling and quantification of iohexol in plasma. The developed, simple and cost-effective LC-MS/MS-method fulfilled all pre-set validation acceptance criteria. Iohexol could be accurately quantified within a haematocrit range of 20-60% and long-term stability of iohexol in VAMS was demonstrated up to 245 days under different storage temperatures. Both iohexol plasma concentrations (r = 0.98, mean bias: -4.20%) and derived GFR values (r = 0.99; mean bias: 1.31%), obtained by a conventional plasma and the VAMS method, demonstrated good correlation and acceptable bias. The agreement between the two methods was especially good for GFR values higher than 60 mL/min/1.73 m2. Nevertheless, for GFR values <60 mL/min/1.73 m2 the accuracy compared to the plasma method was lower. However, small adjustments to the sampling protocol could probably solve this problem.
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Affiliation(s)
- Laura Dhondt
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Siska Croubels
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Pieter De Cock
- Department of Pharmacy, Ghent University Hospital, Corneel Heymanslaan 10, Ghent, Belgium; Heymans Institute of Pharmacology, Ghent University, Corneel Heymanslaan 10, Ghent, Belgium; Department of Paediatric Intensive Care, Ghent University Hospital, Corneel Heymanslaan 10, Ghent, Belgium
| | - Evelyn Dhont
- Department of Paediatric Intensive Care, Ghent University Hospital, Corneel Heymanslaan 10, Ghent, Belgium
| | - Siegrid De Baere
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Peter De Paepe
- Heymans Institute of Pharmacology, Ghent University, Corneel Heymanslaan 10, Ghent, Belgium
| | - Mathias Devreese
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium.
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12
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He Z, Luo Q, Liu Z, Gong L. Extensive evaluation of sample preparation workflow for gas chromatography-mass spectrometry-based plasma metabolomics and its application in rheumatoid arthritis. Anal Chim Acta 2020; 1131:136-145. [DOI: 10.1016/j.aca.2020.06.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/03/2020] [Accepted: 06/10/2020] [Indexed: 12/16/2022]
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13
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El Assri S, Sam H, El Assri A, Bentata Y, Saalaoui E, Rochdi C, Sebbar EH, Choukri M. Iohexol assay for direct determination of glomerular filtration rate: optimization and development of an HPLC-UV method for measurement in serum and urine. Clin Chim Acta 2020; 508:115-121. [DOI: 10.1016/j.cca.2020.04.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 12/11/2022]
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14
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White CA, Akbari A, Allen C, Day AG, Norman PA, Holland D, Adams MA, Knoll GA. Simultaneous glomerular filtration rate determination using inulin, iohexol, and 99mTc-DTPA demonstrates the need for customized measurement protocols. Kidney Int 2020; 99:957-966. [PMID: 32750458 DOI: 10.1016/j.kint.2020.06.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 06/22/2020] [Accepted: 06/26/2020] [Indexed: 11/16/2022]
Abstract
Urinary inulin clearance is considered the gold standard of glomerular filtration rate (GFR) measurement but plasma clearance of less expensive and more accessible tracers is more commonly performed. Many plasma sampling protocols exist but little is known about their accuracy. Here, the study objectives were to compare plasma iohexol and 99mTc-DTPA GFR with varying sampling strategies to the GFR measured by urinary inulin and to identify protocols with the greatest accuracy according to clinical characteristics. GFR was measured simultaneously using urinary inulin, plasma iohexol, and plasma 99mTc DTPA clearance. Blood was sampled from 2 to 10 hours after injection. For each method, bias, precision, and accuracy (P30 and mean absolute error) were calculated for the entire cohort and for eGFR-EPI creatinine subgroups (<30, 30-59, and ≥60 ml/min/1.73m2) and the edema stage using urinary inulin clearance as the gold standard. The mean inulin GFR of the 77 participants was 33 ml/min/1.73m2. Delay of both the initial and the final samples in plasma iohexol protocols yielded the highest accuracy in the setting of low GFR (<30 ml/min/1.73m2). Early initial and final samples yielded the highest accuracy in the setting of high GFRs (≥60 ml/min/1.73m2). No sampling strategy was accurate in edematous patients. Thus, our study demonstrates that customization of GFR protocols according to the anticipated level of GFR are required to optimize protocol accuracy.
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Affiliation(s)
- Christine A White
- Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada.
| | - Ayub Akbari
- Kidney Research Centre, Ottawa Health Research Institute, Ottawa, Ontario, Canada; Division of Nephrology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Celine Allen
- Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Andrew G Day
- Kingston General Health Research Institute, Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Patrick A Norman
- Kingston General Health Research Institute, Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - David Holland
- Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Michael A Adams
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Greg A Knoll
- Kidney Research Centre, Ottawa Health Research Institute, Ottawa, Ontario, Canada; Division of Nephrology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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15
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Quantitation of iohexol, a glomerular filtration marker, in human plasma by LC-MS/MS. J Pharm Biomed Anal 2020; 189:113464. [PMID: 32659569 DOI: 10.1016/j.jpba.2020.113464] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 07/01/2020] [Accepted: 07/05/2020] [Indexed: 11/23/2022]
Abstract
We developed a high-performance liquid chromatography mass spectrometry method for quantitating iohexol in 50 μL human plasma. After acetonitrile protein precipitation, chromatographic separation was achieved with a Shodex Asahipak NH2P-50 2D (5 μm, 2 × 150 mm) column and a gradient of 0.1 % formic acid in acetonitrile and 0.1 % formic acid in water over a 10 min run time. Mass spectrometric detection was performed on a Micromass Quatromicro triple-stage bench-top mass spectrometer with electrospray, positive-mode ionization. The assay was linear from 1 to 500 μg/mL for iohexol, proved to be accurate (101.3-102.1 %) and precise (<3.4 %CV), and fulfilled Food and Drug Administration (FDA) criteria for bioanalytical method validation. Recovery from plasma was 53.1-64.2 % and matrix effect was trivial (-3.4 to -1.3 %). Plasma freeze thaw stability (97.4-99.4 %), stability for 5 months at -80 °C (95.5-103.3 %), and stability for 4 h at room temperature (100.6-103.3 %) were all acceptable. This validated assay using a deuterated internal standard will be an important tool in measuring iohexol clearance and determining glomerular filtration rate (GFR) in patients.
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16
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Enhanced specificity due to method specific limits for relative ion intensities in a high-performance liquid chromatography – tandem mass spectrometry method for iohexol in human serum. ACTA ACUST UNITED AC 2020; 58:709-718. [DOI: 10.1515/cclm-2019-1001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 01/20/2020] [Indexed: 12/26/2022]
Abstract
AbstractBackgroundAccurate assessment of kidney function is needed for a variety of clinical indications and for research. The measurement of the serum clearance of iohexol has emerged as a feasible method to reach this objective. We report the analytical validation and clinical application of a new high-performance liquid chromatography (HPLC) – tandem mass spectrometry (MS/MS) assay to quantify iohexol in human serum. Specificity was enhanced due to the use of method specific acceptance limits for relative ion (RI) intensities.MethodsThe internal standard ioversol was added to 50 μL serum prior to protein precipitation with methanol. Linear gradient elution was performed on a Waters Oasis® HLB column. Three transitions for both iohexol and ioversol were monitored allowing calculation of RIs. Measurements acquired during method validation were used as a training set to establish stricter acceptance criteria for RIs which were then tested retrospectively on clinical routine measurements (86 measurements) and on mathematically simulated interferences.ResultsThe method was linear between 5.0 μg/mL (lower limit of quantification [LLOQ]) and 100.3 μg/mL iohexol. Intraday and interday imprecision were ≤2.6% and ≤3.2%, respectively. Bias was −1.6% to 1.5%. All validation criteria were met, including selectivity, recovery, extraction efficiency and matrix effects. Retrospectively acceptance limits for RIs could be narrowed to ±4 relative standard deviations of the corresponding RIs in the training set. The new limits resulted in an enhanced sensitivity for the simulated interferences.ConclusionsCriteria for validation were met and the assay is now used in our clinical routine diagnostics and in research.
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Schmit DJ, Carroll LJ, Eckfeldt JH, Seegmiller JC. Verification of separate measurement procedures where analytical determinations influence the clinical interpretation of GFR: Iohexol quantitation by HPLC and LC-MS/MS. Clin Biochem 2019; 67:16-23. [DOI: 10.1016/j.clinbiochem.2019.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 10/27/2022]
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18
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Dhondt L, Croubels S, De Cock P, De Paepe P, De Baere S, Devreese M. Development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of iohexol, p-aminohippuric acid and creatinine in porcine and broiler chicken plasma. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1117:77-85. [PMID: 31004849 DOI: 10.1016/j.jchromb.2019.04.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/05/2019] [Accepted: 04/06/2019] [Indexed: 01/03/2023]
Abstract
In order to study the renal function, in terms of glomerular filtration and effective renal plasma flow, in broiler chickens and pigs, an ultra-high performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of iohexol, p-aminohippuric acid (PAH) and exogenously administered creatinine in plasma was developed and validated. Sample preparation consisted of a deproteinization step using methanol for porcine plasma and an Ostro™ Protein Precipitation & Phospholipid Removal Plate was used for broiler chicken plasma. Chromatographic separation was achieved on a Hypersil Gold aQ column using 0.1% formic acid in water and 0.1% formic acid in methanol as mobile phases. The total run time was limited to 10 min. Matrix-matched calibration curves for iohexol and PAH were prepared and good linearity (r ≥ 0.9973; gof ≤ 6.17%) was achieved over the concentration range tested (0.25-90 μg/mL). Limits of quantification were 0.25 μg/mL for iohexol and PAH. Water was used as surrogate matrix for analysis of creatinine in plasma. This surrogate calibration curve showed good linearity over the concentration range tested (0.25-90 μg/mL) (r ≥ 0.9979; gof ≤ 5.66%). For creatinine, the relative lower limit of quantification was 201.03 ± 49.20% and 60.14 ± 7.64% for chicken and porcine plasma, respectively. The results for within-day and between-day precision and accuracy fell within the specified ranges. This straightforward, cost-effective and rapid method, determining iohexol, PAH and creatinine within one single chromatographic run, has been successfully used for the analysis in porcine and broiler chicken plasma samples in order to determine the renal function of these species.
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Affiliation(s)
- Laura Dhondt
- Department of Pharmacology, Toxicology and Biochemistry, Salisburylaan 133, Ghent University, Merelbeke, Belgium.
| | - Siska Croubels
- Department of Pharmacology, Toxicology and Biochemistry, Salisburylaan 133, Ghent University, Merelbeke, Belgium
| | - Pieter De Cock
- Department of Pharmacy, Ghent University Hospital, Corneel Heymanslaan 10, Ghent, Belgium; Heymans Institute of Pharmacology, Ghent University, Corneel Heymanslaan 10, Ghent, Belgium; Department of Paediatric Intensive Care, Ghent University Hospital, Corneel Heymanslaan 10, Ghent, Belgium
| | - Peter De Paepe
- Heymans Institute of Pharmacology, Ghent University, Corneel Heymanslaan 10, Ghent, Belgium
| | - Siegrid De Baere
- Department of Pharmacology, Toxicology and Biochemistry, Salisburylaan 133, Ghent University, Merelbeke, Belgium
| | - Mathias Devreese
- Department of Pharmacology, Toxicology and Biochemistry, Salisburylaan 133, Ghent University, Merelbeke, Belgium.
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Measurement of apixaban, dabigatran, edoxaban and rivaroxaban in human plasma using automated online solid-phase extraction combined with ultra-performance liquid chromatography-tandem mass spectrometry and its comparison with coagulation assays. Clin Chim Acta 2018; 486:347-356. [DOI: 10.1016/j.cca.2018.08.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/06/2018] [Accepted: 08/12/2018] [Indexed: 01/14/2023]
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20
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Turner ME, Laverty KJ, Jeronimo PS, Kaufmann M, Jones G, White CA, Holden RM, Adams MA. Validation of a routine two-sample iohexol plasma clearance assessment of GFR and an evaluation of common endogenous markers in a rat model of CKD. Physiol Rep 2018; 5:5/9/e13205. [PMID: 28483858 PMCID: PMC5430119 DOI: 10.14814/phy2.13205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 02/13/2017] [Indexed: 11/24/2022] Open
Abstract
Endogenous markers of kidney function are insensitive to early declines in glomerular filtration rate (GFR) and in rodent models, validated, practical alternatives are unavailable. In this study, we determined GFR by modeling the plasma clearance of two compounds, iohexol and inulin, and compared the findings to common endogenous markers. All plasma clearance methods of both iohexol and inulin detected a decline in renal function weeks prior to any increase in endogenous marker. Iohexol plasma clearance and inulin plasma clearance had a very high agreement and minimal bias when using 12‐sample models. However, only iohexol could be accurately simplified to a two‐sample, one‐compartment estimation strategy. Following an IV injection of low‐dose iohexol and two timed blood samples at 30 and 90 min, one can accurately approximate a complex 12‐sample strategy of plasma clearance. This method is simple enough to use in routine, longitudinal analysis of larger cohort animal studies.
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Affiliation(s)
- Mandy E Turner
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Kimberly J Laverty
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Paul S Jeronimo
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Martin Kaufmann
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Glenville Jones
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Christine A White
- Department of Medicine, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Rachel M Holden
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada.,Department of Medicine, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
| | - Michael A Adams
- Department of Biomedical and Molecular Sciences, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada
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Seegmiller JC, Eckfeldt JH, Lieske JC. Challenges in Measuring Glomerular Filtration Rate: A Clinical Laboratory Perspective. Adv Chronic Kidney Dis 2018; 25:84-92. [PMID: 29499892 DOI: 10.1053/j.ackd.2017.10.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 11/11/2022]
Abstract
The assessment of kidney function is a cornerstone in the clinical management and health of the patient. Although the kidneys perform many physiologic functions and are essential for maintaining homeostasis, kidney function is typically evaluated, quantitated, and understood using the glomerular filtration rate (GFR). Although GFR can be directly measured using a variety of externally administered glomerular filtration markers, in general practice, the GFR is usually estimated (eGFR) using endogenous markers that are cleared primarily by kidney filtration. Common situations exist where the GFR needs to be measured (mGFR) in order to proceed with care. This manuscript will review laboratory challenges in the assessment of GFR. Key points to consider when implementing a mGFR testing protocol are the following: marker selection, clearance methodology (urinary vs solely plasma measurements of filtration marker), sample collection, number of samples to collect, staff required, and analytical measurement technology for the filtration marker selected. We suggest those wanting to implement mGFR testing examine site-specific institutional resources along with patient population and proceed with the approaches best suited for their clinical needs and laboratory resources available.
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Liu X, Peng D, Tian H, Lu C. Simple equation for calculation of plasma clearance for evaluation of renal function without urine collection in rats. Nephrology (Carlton) 2016; 22:89-94. [PMID: 28004487 DOI: 10.1111/nep.12826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To develop an equation for the evaluation of renal function in rats using three dilutions of plasma samples and to validate this method by comparison with a reference method. The investigation was conducted in Sprague-Dawley (SD) rats after delivery of three doses of iohexol, with blood samples collected before and after dosage using a quantitative blood collection method. Plasma iohexol concentrations were detected by high performance liquid chromatography (HPLC). The extraction recovery of iohexol from plasma was >97.30% and the calibration curve was linear (r2 = 0.9997) over iohexol concentrations ranging from 10 to 1000 µg/mL. The method had an RE of <9.310 and intra- and inter-day RSD of <5.137% and <3.693%, respectively. The plasma clearance values obtained from the equation correlated closely (r = 0.763) with those obtained using the reference method. The relatively correlation in the results obtained using the method under investigation and the reference method indicate that this new equation can be used for preliminary assessment of renal function in rats.
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Affiliation(s)
- Xiang Liu
- Department of Pharmacology, Faculty of Pharmacy, Guangdong Medical University, Dongguan, Guangdong, China
| | - Dejun Peng
- Department of Pharmacology, Faculty of Pharmacy, Guangdong Medical University, Dongguan, Guangdong, China
| | - Hao Tian
- Department of Pharmacology, Faculty of Pharmacy, Guangdong Medical University, Dongguan, Guangdong, China
| | - Chengyu Lu
- Department of Pharmacology, Faculty of Pharmacy, Guangdong Medical University, Dongguan, Guangdong, China
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Nyssen L, Delanaye P, Le Goff C, Peeters S, Cavalier É. A simple LC-MS method for the determination of iohexol and iothalamate in serum, using ioversol as an internal standard. Clin Chim Acta 2016; 463:96-102. [DOI: 10.1016/j.cca.2016.10.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 12/31/2022]
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Abstract
Although mass spectrometry has been used clinically for decades, the advent of immunoassay technology moved the clinical laboratory to more labor saving automated platforms requiring little if any sample preparation. It became clear, however, that immunoassays lacked sufficient sensitivity and specificity necessary for measurement of certain analytes or for measurement of analytes in specific patient populations. This limitation prompted clinical laboratories to revisit mass spectrometry which could additionally be used to develop assays for which there was no commercial source. In this chapter, the clinical applications of mass spectrometry in therapeutic drug monitoring, toxicology, and steroid hormone analysis will be reviewed. Technologic advances and new clinical applications will also be discussed.
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Affiliation(s)
- D French
- University of California San Francisco, San Francisco, CA, United States.
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25
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Delanaye P, Ebert N, Melsom T, Gaspari F, Mariat C, Cavalier E, Björk J, Christensson A, Nyman U, Porrini E, Remuzzi G, Ruggenenti P, Schaeffner E, Soveri I, Sterner G, Eriksen BO, Bäck SE. Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 1: How to measure glomerular filtration rate with iohexol? Clin Kidney J 2016; 9:682-99. [PMID: 27679715 PMCID: PMC5036902 DOI: 10.1093/ckj/sfw070] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/08/2016] [Indexed: 01/31/2023] Open
Abstract
While there is general agreement on the necessity to measure glomerular filtration rate (GFR) in many clinical situations, there is less agreement on the best method to achieve this purpose. As the gold standard method for GFR determination, urinary (or renal) clearance of inulin, fades into the background due to inconvenience and high cost, a diversity of filtration markers and protocols compete to replace it. In this review, we suggest that iohexol, a non-ionic contrast agent, is most suited to replace inulin as the marker of choice for GFR determination. Iohexol comes very close to fulfilling all requirements for an ideal GFR marker in terms of low extra-renal excretion, low protein binding and in being neither secreted nor reabsorbed by the kidney. In addition, iohexol is virtually non-toxic and carries a low cost. As iohexol is stable in plasma, administration and sample analysis can be separated in both space and time, allowing access to GFR determination across different settings. An external proficiency programme operated by Equalis AB, Sweden, exists for iohexol, facilitating interlaboratory comparison of results. Plasma clearance measurement is the protocol of choice as it combines a reliable GFR determination with convenience for the patient. Single-sample protocols dominate, but multiple-sample protocols may be more accurate in specific situations. In low GFRs one or more late samples should be included to improve accuracy. In patients with large oedema or ascites, urinary clearance protocols should be employed. In conclusion, plasma clearance of iohexol may well be the best candidate for a common GFR determination method.
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Affiliation(s)
- Pierre Delanaye
- Department of Nephrology, Dialysis and Transplantation , University of Liège Hospital (ULg CHU) , Liège , Belgium
| | - Natalie Ebert
- Charité University Medicine , Institute of Public Health , Berlin , Germany
| | - Toralf Melsom
- Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway; Section of Nephrology, University Hospital of North Norway, Tromsø, Norway
| | - Flavio Gaspari
- IRCCS - Istituto di Ricerche Farmacologiche 'Mario Negri', Centro di Ricerche Cliniche per le Malattie Rare 'Aldo e Cele Daccò', Ranica, Bergamo, Italy
| | - Christophe Mariat
- Department of Nephrology, Dialysis, Transplantation and Hypertension , CHU Hôpital Nord, University Jean Monnet, PRES Université de LYON , Saint-Etienne , France
| | - Etienne Cavalier
- Department of Clinical Chemistry , University of Liège Hospital (ULg CHU) , Liège , Belgium
| | - Jonas Björk
- Department of Occupational and Environmental Medicine , Lund University , Lund , Sweden
| | | | - Ulf Nyman
- Department of Translational Medicine, Division of Medical Radiology , Skåne University Hospital , Malmö , Sweden
| | - Esteban Porrini
- University of La Laguna, CIBICAN-ITB, Faculty of Medicine, Hospital Universtario de Canarias, La Laguna, Tenerife , Spain
| | - Giuseppe Remuzzi
- Centro di Ricerche Cliniche per le Malattie Rare 'Aldo e Cele Daccò, Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy; Unit of Nephrology, Azienda Socio Sanitaria Territoriale (ASST) Ospedale Papa Giovanni XXIII, Bergamo, Italy
| | - Piero Ruggenenti
- Centro di Ricerche Cliniche per le Malattie Rare 'Aldo e Cele Daccò, Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy; Unit of Nephrology, Azienda Socio Sanitaria Territoriale (ASST) Ospedale Papa Giovanni XXIII, Bergamo, Italy
| | - Elke Schaeffner
- Charité University Medicine , Institute of Public Health , Berlin , Germany
| | - Inga Soveri
- Department of Medical Sciences , Uppsala University , Uppsala , Sweden
| | - Gunnar Sterner
- Department of Nephrology , Skåne University Hospital , Malmö , Sweden
| | - Bjørn Odvar Eriksen
- Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway; Section of Nephrology, University Hospital of North Norway, Tromsø, Norway
| | - Sten-Erik Bäck
- Department of Clinical Chemistry , Skåne University Hospital , Lund , Sweden
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Chaloemsuwiwattanakan T, Sangcakul A, Kitiyakara C, Nacapricha D, Wilairat P, Chaisuwan P. Simple and fast analysis of iohexol in human serums using micro-hydrophilic interaction liquid chromatography with monolithic column. J Sep Sci 2016; 39:3521-7. [PMID: 27443792 DOI: 10.1002/jssc.201600475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/10/2016] [Accepted: 07/13/2016] [Indexed: 11/06/2022]
Abstract
A simple and rapid method based on micro-liquid chromatography using a synthetic monolithic capillary column was developed for determination of iohexol in human serums, a marker to evaluate the glomerular filtration rate. A hydrophilic methacrylic acid-ethylene dimethacrylate monolith provided excellent selectivity and efficiency for iohexol with separation time of 3 min using a mobile phase of 40:60 v/v 50 mM phosphate buffer pH 5/methanol. Four serum protein removal, methods using perchloric acid, 50% acetonitrile, 0.1 M zinc sulfate, and centrifuge membrane filter were examined. The method of zinc sulfate was chosen due to its simplicity, compatibility with the mobile phase system, nontoxicity, and low cost. Interday calibration curves were conducted over iohexol concentrations range of 2-500 mg/L (R(2) = 0.9997 ± 0.0001) with detection limit of 0.44 mg/L. Intra- and interday precisions for peak area and retention time were less than 2.8 and 1.4%, respectively. The method was successfully applied to serum samples with percent recoveries from 102 to 104. The method was applied to monitor released iohexol from healthy subject. Compared with the commercially available reversed-phase high-performance liquid chromatography method, the presented method provided simpler chromatogram, faster separation with higher separation efficiency and much lower sample and solvent consumption.
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Affiliation(s)
| | - Areeporn Sangcakul
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Chagriya Kitiyakara
- Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Duangjai Nacapricha
- Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs.).,Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Prapin Wilairat
- Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs.).,National Doping Control Centre, Mahidol University, Bangkok, Thailand
| | - Patcharin Chaisuwan
- Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs.). .,School of Chemistry, Institute of Science, Suranaree University of Technology, Muang District, Nakhon Ratchasima, Thailand.
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Schwertner HA, Weld KJ. High-Performance Liquid-Chromatographic Analysis of Plasma Iohexol Concentrations. J Chromatogr Sci 2015; 53:1475-80. [DOI: 10.1093/chromsci/bmv040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Indexed: 11/13/2022]
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Hellqvist A, Heiene R, De Baere S, Croubels S, Hedeland Y. Development of a capillary electrophoretic method for determination of plasma clearance of iohexol in dogs and cats. Biomed Chromatogr 2014; 29:504-13. [DOI: 10.1002/bmc.3304] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/20/2014] [Accepted: 07/04/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Alexander Hellqvist
- Uppsala University; Department of Medicinal Chemistry, Division of Analytical Pharmaceutical Chemistry, Biomedical Centre; Husargatan 3 PO Box 574 SE-751 23 Uppsala Sweden
| | - Reidun Heiene
- Dept. of Companion Animal Clinical Sciences; Norwegian School of Veterinary Science; PO Box 8146, N-0033 Oslo, Norway, and Blåstjärnans Djursjukhus, Gjutjärnsgatan 4 SE-417 07 Gothenburg Sweden
| | - Siegrid De Baere
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine; Ghent University; Salisburylaan 133 9820 Merelbeke Belgium
| | - Siska Croubels
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine; Ghent University; Salisburylaan 133 9820 Merelbeke Belgium
| | - Ylva Hedeland
- Uppsala University; Department of Medicinal Chemistry, Division of Analytical Pharmaceutical Chemistry, Biomedical Centre; Husargatan 3 PO Box 574 SE-751 23 Uppsala Sweden
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Brezina U, Valenta H, Rempe I, Kersten S, Humpf HU, Dänicke S. Development of a liquid chromatography tandem mass spectrometry method for the simultaneous determination of zearalenone, deoxynivalenol and their metabolites in pig serum. Mycotoxin Res 2014; 30:171-86. [PMID: 24925826 DOI: 10.1007/s12550-014-0200-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/25/2014] [Accepted: 05/27/2014] [Indexed: 11/29/2022]
Abstract
A sensitive and selective liquid chromatography tandem mass spectrometry method using negative electrospray ionisation (LC-ESI-MS/MS) was developed for the simultaneous determination of zearalenone (ZEN), deoxynivalenol (DON) and their metabolites α-zearalenol, β-zearalenol, zearalanone, α-zearalanol, β-zearalanol and de-epoxy-deoxynivalenol in pig serum. For method development, different sample preparation columns were tested for their suitability for extraction and clean up. Finally, preparation of serum samples was carried out using Oasis™ HLB solid-phase extraction (SPE) columns. The analyte concentrations were determined by the use of isotopically labelled internal standards (IS). The method was in-house validated for all analytes. Calibration graphs (0.3-480 ng/ml) were prepared and high degree of linearity was achieved (r ≥ 0.99). Results for method precision ranged between 2.7 and 21.5 % for inter-day and between 1.1 and 11.1 % for intra-day. The recoveries were in the range of 82-131 %. Limits of detection and quantification ranged 0.03-0.71 and 0.08-2.37 ng/ml, respectively. The method has been successfully used for quantitative determination of ZEN, DON and their metabolites in pig serum from a feeding trial with practically relevant ZEN and DON concentrations. This method is precise and reproducible and can be used as a multi-biomarker method to assess animal exposure to these mycotoxins and for diagnosis of intoxications.
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Affiliation(s)
- Ulrike Brezina
- Institute of Animal Nutrition, Federal Research Institute for Animal Health, Friedrich-Loeffler-Institut, Braunschweig, Germany
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Retention mechanism assessment and method development for the analysis of iohexol and its related compounds in hydrophilic interaction liquid chromatography. Anal Bioanal Chem 2014; 406:4217-32. [DOI: 10.1007/s00216-014-7808-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/05/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
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Leung KSY, Fong BMW. LC–MS/MS in the routine clinical laboratory: has its time come? Anal Bioanal Chem 2013; 406:2289-301. [DOI: 10.1007/s00216-013-7542-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/18/2013] [Accepted: 11/28/2013] [Indexed: 11/30/2022]
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32
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Kuhn J, Knabbe C. Fully validated method for rapid and simultaneous measurement of six antiepileptic drugs in serum and plasma using ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry. Talanta 2013; 110:71-80. [DOI: 10.1016/j.talanta.2013.02.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 01/26/2013] [Accepted: 02/05/2013] [Indexed: 11/24/2022]
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Quantitative determination of exo- and endo-iohexol in canine and feline samples using high performance liquid chromatography with ultraviolet detection. J Pharm Biomed Anal 2012; 61:50-6. [DOI: 10.1016/j.jpba.2011.11.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 11/18/2011] [Accepted: 11/21/2011] [Indexed: 11/21/2022]
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