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Ebert N, Schaeffner E, Seegmiller JC, van Londen M, Bökenkamp A, Cavalier E, Delanaye P, Derain-Dubourg L, Eriksen BO, Indridason OS, Palsson R, Shafi T, Christensson A, Bevc S, Carrara F, Courbebaisse M, Dalton RN, van der Giet M, Melsom T, Methven S, Nordin G, Pottel H, Rule AD, Trillini M, White CA. Iohexol plasma clearance measurement protocol standardization for adults: a consensus paper of the European Kidney Function Consortium. Kidney Int 2024; 106:583-596. [PMID: 39097002 DOI: 10.1016/j.kint.2024.06.029] [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: 02/20/2024] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 08/05/2024]
Abstract
International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the integration of mGFR testing in both clinical and research settings. To this end, the European Kidney Function Consortium convened an international group of experts with relevant experience in mGFR. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using 1-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, and safe, can be assayed at a central laboratory, and the other commonly used non-radio-labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected over urine clearance as it requires no urine collection. A 1 compartment was preferred to 2 compartments as it requires fewer samples. The recommendations are based on published evidence complemented by expert opinion. The consensus paper covers practical advice for patients and health professionals, preparation, administration, and safety aspects of iohexol, laboratory analysis, blood sample collection and sampling times using both multiple and single-sample protocols, description of the mGFR mathematical calculations, as well as implementation strategies. Supplementary materials include patient and provider information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation.
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Affiliation(s)
- Natalie Ebert
- Charité Universitätsmedizin Berlin, Institute of Public Health, Berlin, Germany
| | - Elke Schaeffner
- Charité Universitätsmedizin Berlin, Institute of Public Health, Berlin, Germany
| | - Jesse C Seegmiller
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Marco van Londen
- Division of Nephrology, Department of Internal Medicine, University Medical Center Groningen, Groningen, the Netherlands
| | - Arend Bökenkamp
- Department of Pediatric Nephrology, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liège, Centre Hospitalier Universitaire du Sart-Tilman, Liège, Belgium
| | - Pierre Delanaye
- Department of Nephrology-Dialysis-Transplantation, University of Liège, Centre Hospitalier Universitaire du Sart-Tilman, Liège (ULiege), Belgium; Department of Nephrology-Dialysis-Apheresis, Hôpital Universitaire Carémeau, Nîmes, France
| | - Laurence Derain-Dubourg
- Service de Néphrologie, Dialyse, Hypertension et Exploration Fonctionnelle Rénale, Centre de Référence des Maladies Rénales Rares, Service de Néphrologie et Rhumatologie Pédiatriques, Hospices Civils de Lyon, Lyon, France
| | - Bjørn O Eriksen
- Section of Nephrology, University Hospital of North Norway and Metabolic and Renal Research Group, UiT, The Arctic University of Norway, Tromsø, Norway
| | | | - Runolfur Palsson
- Division of Nephrology, Landspitali University Hospital, Reykavik, Iceland; Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Tariq Shafi
- Division of Kidney Diseases, Hypertension and Transplantation, Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Anders Christensson
- Department of Nephrology, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Sebastjan Bevc
- Department of Nephrology, Department of Pharmacology, University Medical Centre Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Fabiola Carrara
- Clinical Research Center for Rare Diseases, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Marie Courbebaisse
- Université Paris Cité; Physiology Department, Hôpital Européen Georges-Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - R Neil Dalton
- The WellChild Laboratory, Evelina London Children's Hospital, London, UK
| | - Markus van der Giet
- Department of Nephrology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Toralf Melsom
- Section of Nephrology, University Hospital of North Norway and Metabolic and Renal Research Group, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Shona Methven
- Department of Renal Medicine, Aberdeen Royal Infirmary, Scotland, UK
| | | | - Hans Pottel
- Department of Public Health and Primary Care, Katholieke Universiteit Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Andrew D Rule
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Matias Trillini
- Clinical Research Center for Rare Diseases, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Christine A White
- Department of Medicine, Queen's University, Kingston, Ontario, Canada.
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Zwart TC, Metscher E, van der Boog PJM, Swen JJ, de Fijter JW, Guchelaar H, de Vries APJ, Moes DJAR. Volumetric microsampling for simultaneous remote immunosuppressant and kidney function monitoring in outpatient kidney transplant recipients. Br J Clin Pharmacol 2022; 88:4854-4869. [PMID: 35670960 PMCID: PMC9796409 DOI: 10.1111/bcp.15433] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/20/2022] [Accepted: 05/25/2022] [Indexed: 01/01/2023] Open
Abstract
AIMS Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow-up. Microsamples enable remote sampling and minimise patient burden as compared to conventional venous sampling at the clinic. We developed a liquid chromatography-tandem mass spectrometry assay to quantify tacrolimus, mycophenolic acid (MPA), creatinine and iohexol in dried blood spot (DBS), and volumetric absorptive microsample (VAMS) samples. METHODS The assay was successfully validated analytically for all analytes. Clinical validation was conducted by direct comparison of paired DBS, VAMS and venous reference samples from 25 kidney transplant recipients. Patients received iohexol 5-15 minutes before immunosuppressant intake and were sampled 0, 1, 2 and 3 hours thereafter, enabling tacrolimus and MPA area under the concentration-time curve (AUC) and creatinine-based and iohexol-based glomerular filtration rate (GFR) estimation. Method agreement was evaluated using Passing-Bablok regression, Bland-Altman analysis and the percentages of values within 15-30% of the reference (P15 -P30 ) with a P20 acceptance threshold of 80%. RESULTS For DBS samples, method agreement was excellent for tacrolimus trough concentrations (n = 25, P15 = 92.0%) and AUCs (n = 25; P20 = 95.8%) and adequate for creatinine-based GFR trend monitoring (n = 25; P20 = 80%). DBS-based MPA AUC assessment showed suboptimal agreement (n = 16; P20 = 68.8%), but was considered acceptable given its P30 of 100%. The assay performed inadequately for DBS-based iohexol GFR determination (n = 24; P20 = 75%). The VAMS technique generally showed inferior performance, but can be considered for certain situations. CONCLUSION The assay was successfully validated for tacrolimus, MPA and creatinine quantification in DBS samples, enabling simultaneous remote kidney function trend monitoring and immunosuppressant therapeutic drug monitoring in kidney transplant recipients.
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Affiliation(s)
- Tom C. Zwart
- Department of Clinical Pharmacy and ToxicologyLeiden University Medical CenterLeidenThe Netherlands
| | - Erik Metscher
- Department of Clinical Pharmacy and ToxicologyLeiden University Medical CenterLeidenThe Netherlands
| | - Paul J. M. van der Boog
- Department of Internal Medicine (Nephrology)Leiden University Medical CenterLeidenThe Netherlands
- LUMC Transplant CenterLeiden University Medical CenterLeidenThe Netherlands
| | - Jesse J. Swen
- Department of Clinical Pharmacy and ToxicologyLeiden University Medical CenterLeidenThe Netherlands
| | - Johan W. de Fijter
- Department of Internal Medicine (Nephrology)Leiden University Medical CenterLeidenThe Netherlands
- LUMC Transplant CenterLeiden University Medical CenterLeidenThe Netherlands
| | - Henk‐Jan Guchelaar
- Department of Clinical Pharmacy and ToxicologyLeiden University Medical CenterLeidenThe Netherlands
| | - Aiko P. J. de Vries
- Department of Internal Medicine (Nephrology)Leiden University Medical CenterLeidenThe Netherlands
- LUMC Transplant CenterLeiden University Medical CenterLeidenThe Netherlands
| | - Dirk Jan A. R. Moes
- Department of Clinical Pharmacy and ToxicologyLeiden University Medical CenterLeidenThe Netherlands
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Kaenkangploo D, Kampa N, Jitpean S, Seesupa S, Yongvanit K. Assessment of glomerular filtration rate measurement in dogs using dynamic contrast CT compared to serum iohexol clearance. Vet Radiol Ultrasound 2021; 63:38-46. [PMID: 34637569 DOI: 10.1111/vru.13024] [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: 02/09/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 11/30/2022] Open
Abstract
Dynamic contrast CT with Patlak plot analysis can be used to determine the glomerular filtration rate (GFR). However, several studies have shown different GFR values and they are most likely less than the values by the standard techniques. The purpose of this prospective, experimental, and method comparison study was to evaluate the GFR using a CT technique (CT-GFR) in 12 healthy dogs compared to serum iohexol clearance (SIC-GFR). All dogs were anesthetized and placed in the right lateral recumbency position and the caudal part was lifted inside the CT gantry. A single-slice dynamic CT of the aorta and both kidneys was scanned sequentially every 2 s for 2 min after a bolus injection (3 mL/s) of iohexol (300 mg/kg). Time attenuation curves (TAC) were constructed and the GFR per volume of kidney was calculated using the Patlak plot analysis method based on 30-120 s time intervals, and results were compared to global GFR from SIC that was determined with eight blood samples for up to 240 min. The CT-GFR value (1.85 ± 0.48 mL/min/kg) was significantly less than the SIC-GFR value (3.40 ± 0.80 mL/min/kg; P < .05). The CT-GFR was correlated with SIC-GFR by the coefficient of correlation (r) at 0.61 (P = .046). In conclusion, the CT-GFR underestimated SIC-GFR and should be used carefully. We suggest that the GFR should be calculated using the equation derived from linear regression between CT-GFR and the standard GFR method. With its own particular parameters, each institute should have its own prediction equation.
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Affiliation(s)
- Duangdaun Kaenkangploo
- Division of Surgery, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Naruepon Kampa
- Division of Surgery, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Supranee Jitpean
- Division of Surgery, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Suvaluk Seesupa
- Division of Surgery, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Karn Yongvanit
- Veterinary Teaching Hospital, Khon Kaen University, Khon Kaen, Thailand
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Speeckaert MM, Seegmiller J, Glorieux G, Lameire N, Van Biesen W, Vanholder R, Delanghe JR. Measured Glomerular Filtration Rate: The Query for a Workable Golden Standard Technique. J Pers Med 2021; 11:949. [PMID: 34683089 PMCID: PMC8541429 DOI: 10.3390/jpm11100949] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 01/12/2023] Open
Abstract
Inulin clearance has, for a long time, been considered as the reference method to determine measured glomerular filtration rates (mGFRs). However, given the known limitations of the standard marker, serum creatinine, and of inulin itself, and the frequent need for accurate GFR estimations, several other non-radioactive (iohexol and iothalamate) and radioactive (51Cr-EDTA, 99mTc-DTPA, 125I iothalamate) exogenous mGFR filtration markers are nowadays considered the most accurate options to evaluate GFR. The availability of 51Cr-EDTA is limited, and all methods using radioactive tracers necessitate specific safety precautions. Serum- or plasma-based certified reference materials for iohexol and iothalamate and evidence-based protocols to accurately and robustly measure GFR (plasma vs. urinary clearance, single-sample vs. multiple-sample strategy, effect of sampling time delay) are lacking. This leads to substantial variation in reported mGFR results across studies and questions the scientific reliability of the alternative mGFR methods as the gold standard to evaluate kidney function. On top of the scientific discussion, regulatory issues are further narrowing the clinical use of mGFR methods. Therefore, this review is a call for standardization of mGFR in terms of three aspects: the marker, the analytical method to assess concentrations of that marker, and the procedure to determine GFR in practice. Moreover, there is also a need for an endogenous filtration marker or a panel of filtration markers from a single blood draw that would allow estimation of GFR as accurately as mGFR, and without the need for application of anthropometric, clinical, and demographic characteristics.
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Affiliation(s)
- Marijn M. Speeckaert
- Department of Nephrology, Ghent University Hospital, 9000 Ghent, Belgium; (G.G.); (N.L.); (W.V.B.); (R.V.)
- Research Foundation Flanders, 1000 Brussels, Belgium
| | - Jesse Seegmiller
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA;
| | - Griet Glorieux
- Department of Nephrology, Ghent University Hospital, 9000 Ghent, Belgium; (G.G.); (N.L.); (W.V.B.); (R.V.)
| | - Norbert Lameire
- Department of Nephrology, Ghent University Hospital, 9000 Ghent, Belgium; (G.G.); (N.L.); (W.V.B.); (R.V.)
| | - Wim Van Biesen
- Department of Nephrology, Ghent University Hospital, 9000 Ghent, Belgium; (G.G.); (N.L.); (W.V.B.); (R.V.)
| | - Raymond Vanholder
- Department of Nephrology, Ghent University Hospital, 9000 Ghent, Belgium; (G.G.); (N.L.); (W.V.B.); (R.V.)
| | - Joris R. Delanghe
- Department of Diagnostic Sciences, Ghent University, 9000 Ghent, Belgium;
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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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Chen Y, Zelnick LR, Hoofnagle AN, Yeung CK, Shireman LM, Phillips B, Brauchla CC, de Boer I, Manahan L, Heckbert SR, Himmelfarb J, Kestenbaum BR. Prediction of Kidney Drug Clearance: A Comparison of Tubular Secretory Clearance and Glomerular Filtration Rate. J Am Soc Nephrol 2021; 32:459-468. [PMID: 33239392 PMCID: PMC8054886 DOI: 10.1681/asn.2020060833] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/23/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Although proximal tubular secretion is the primary mechanism of kidney drug elimination, current kidney drug dosing strategies are on the basis of eGFR. METHODS In a dedicated pharmacokinetic study to compare GFR with tubular secretory clearance for predicting kidney drug elimination, we evaluated stable outpatients with eGFRs ranging from 21 to 140 ml/min per 1.73 m2. After administering single doses of furosemide and famciclovir (metabolized to penciclovir), we calculated their kidney clearances on the basis of sequential plasma and timed urine measurements. Concomitantly, we quantified eight endogenous secretory solutes in plasma and urine using liquid chromatography-tandem mass spectrometry and measured GFR by iohexol clearance (iGFR). We computed a summary secretion score as the scaled average of the secretory solute clearances. RESULTS Median iGFR of the 54 participants was 73 ml/min per 1.73 m2. The kidney furosemide clearance correlated with iGFR (r=0.84) and the summary secretion score (r=0.86). The mean proportionate error (MPE) between iGFR-predicted and measured furosemide clearance was 30.0%. The lowest MPE was observed for the summary secretion score (24.1%); MPEs for individual secretory solutes ranged from 27.3% to 48.0%. These predictive errors were statistically indistinguishable. Penciclovir kidney clearance was correlated with iGFR (r=0.83) and with the summary secretion score (r=0.91), with similar predictive accuracy of iGFR and secretory clearances. Combining iGFR with the summary secretion score yielded only modest improvements in the prediction of the kidney clearance of furosemide and penciclovir. CONCLUSIONS Secretory solute clearance measurements can predict kidney drug clearances. However, tight linkage between GFR and proximal tubular secretory clearance in stable outpatients provides some reassurance that GFR, even when estimated, is a useful surrogate for predicting secretory drug clearances in such patients.
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Affiliation(s)
- Yan Chen
- Department of Epidemiology, University of Washington, Seattle, Washington,Kidney Research Institute, Seattle, Washington
| | - Leila R. Zelnick
- Kidney Research Institute, Seattle, Washington,Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
| | - Andrew N. Hoofnagle
- Kidney Research Institute, Seattle, Washington,Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Catherine K. Yeung
- Kidney Research Institute, Seattle, Washington,Department of Pharmacy, University of Washington, Seattle, Washington
| | - Laura M. Shireman
- Department of Pharmacy, University of Washington, Seattle, Washington
| | - Brian Phillips
- Department of Pharmacy, University of Washington, Seattle, Washington
| | | | - Ian de Boer
- Kidney Research Institute, Seattle, Washington,Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
| | - Linda Manahan
- Kidney Research Institute, Seattle, Washington,Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
| | - Susan R. Heckbert
- Department of Epidemiology, University of Washington, Seattle, Washington,Department of Pharmacy, University of Washington, Seattle, Washington
| | - Jonathan Himmelfarb
- Kidney Research Institute, Seattle, Washington,Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
| | - Bryan R. Kestenbaum
- Kidney Research Institute, Seattle, Washington,Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
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Seegmiller JC, Eckfeldt JH. Racial Demographics in Glomerular Filtration Rate Estimating Equations. Clin Chem 2020; 66:1485-1488. [PMID: 33257981 DOI: 10.1093/clinchem/hvaa234] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/02/2020] [Indexed: 01/09/2023]
Affiliation(s)
- Jesse C Seegmiller
- Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota, Minneapolis, MN
| | - John H Eckfeldt
- Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota, Minneapolis, MN
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Assessment of Kidney Function in Patients With Extreme Obesity: A Narrative Review. Ann Pharmacother 2020; 55:80-88. [DOI: 10.1177/1060028020935580] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Objectives: To discuss the evidence and caveats associated with estimated and measured creatinine clearance (eClCr and mClCr) and glomerular filtration rate (eGFR and mGFR) assessments of kidney function in patients with more extreme forms of obesity. Data Sources: PubMed (1976 to mid-May 2020) was used, with bibliographies of retrieved articles searched for additional articles. Study Selection and Data Extraction: Articles using gold standard mGFR to evaluate eClCr, mClCr, and eGFR assessments of kidney function in patients with more extreme forms of obesity were included. Data Synthesis: The overestimation of GFR by mClCr is well established, but mClCr is an alternative to mGFR assessments for determining medication dosing in patients with extremes of body size or muscle mass, or in patients receiving narrow therapeutic index medications when eGFR is likely to be inaccurate. The vast majority of studies comparing eGFR assessments with gold standard indicators of kidney function were attempts to validate eGFR equations for diagnosing and staging chronic kidney disease (CKD). Relevance to Patient Care and Clinical Practice: For dosing medications in patients with stable kidney function and extreme obesity, a deindexed 4-variable Modification of Diet in Renal Disease or CKD Epidemiology Collaboration equation is an alternative to Cockcroft-Gault. Consistent use of the same equation by provider and between providers within any given setting is of paramount importance. Conclusions: In patients with extreme obesity and stable kidney function, eClCr or eGFR using deindexed values provides estimates of function for dosing adjustments of medications with elimination by the kidneys, but more research is needed with respect to the best size descriptor to use with estimating equations.
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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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