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Zhou C, Xie Q, Wang H, Wu F, He D, Huang Y, He Y, Dai S, Chen J, Kong L, Zhang Y. Biological variation in the estimated glomerular filtration rate of healthy individuals within 24 h calculated using 2021CKD-EPI equations. Ir J Med Sci 2024; 193:1613-1620. [PMID: 38308766 DOI: 10.1007/s11845-024-03621-9] [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: 09/05/2023] [Accepted: 01/25/2024] [Indexed: 02/05/2024]
Abstract
BACKGROUND AND AIMS Use the MDRD (Modification of Diet in Renal Disease) and 2021 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation void of race coefficients (CKD-EPICrea, CKD-EPICys-C, and CKD-EPICrea+Cys-C) to estimate the BV (Biological variation) of eGFR (estimated glomerular filtration rate) within 24 h in a healthy population to help explain future studies using eGFR in the context of a known BV. METHODS Blood samples were collected from 30 healthy subjects at six time points within 24 h. Serum creatinine (S-Crea) and serum cystatin C (S-Cys-C) were measured, and the BV of eGFR was calculated. Outlier and variance homogeneity analyses were performed, followed by CV-ANOVA on trend-corrected data. RESULTS The eGFR CVI for the four equations (MDRD, CKD-EPICrea, CKD-EPICys-C, and CKD-EPICrea+Cys-C) were 8.39% (7.50-9.51%), 3.90% (3.49-4.42%), 6.58% (5.88-7.46%), and 5.03% (4.50-5.71%), respectively. The corresponding II and RCVpos/neg values were 0.69, 0.48, 0.51, and 0.31, and (29.30%, - 22.66%), (12.69%, - 11.2 6%), (20.97%, - 17.33%), and (15.88%, - 13.70%), respectively; RCVpos /neg of eGFR was highest in the MDRD equation and lowest in the CKD-EPI Crea equation. Additionally, the RCVpos/neg values of the individual was highest in the MDRD equation and lowest in the CKD-EPICrea+Cys-C equation; they are (56.51%, - 36.11%) and (5.01%, - 4.77%), respectively. CONCLUSIONS We present data on the 24 h BV eGFR of the 2021 CKD-EPI equations. The presence of BV has impact on the interpretation of GFR results, affecting CKD disease grading. The RCVpos/neg differences were large among the individuals. When using eGFRs based on the MDRD and CKD-EPI equations, it is necessary to combine RCVpos/neg values before interpreting the results.
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Affiliation(s)
- ChaoQiong Zhou
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - QianRong Xie
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
- Department of Clinical Laboratory, The Third People's Hospital of Chengdu, Chengdu, Sichuan, 610000, China
| | - HuaLi Wang
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - Feng Wu
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - DaHai He
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - Ying Huang
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - Ying He
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - ShiRong Dai
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - Jie Chen
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China
| | - LiRui Kong
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China.
| | - Yan Zhang
- Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of Pidu District, No. 342, South Street, Pidu District, Chengdu, Sichuan, 611730, China.
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Moreno-Parro I, Diaz-Garzon J, Aarsand AK, Sandberg S, Aikin R, Equey T, Ríos-Blanco JJ, Buño Soto A, Fernandez-Calle P. Biological Variation Data in Triathletes for Metabolism and Growth-Related Biomarkers Included in the Athlete Biological Passport. Clin Chem 2024:hvae072. [PMID: 38781424 DOI: 10.1093/clinchem/hvae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/08/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND When using biological variation (BV) data, BV estimates need to be robust and representative. High-endurance athletes represent a population under special physiological conditions, which could influence BV estimates. Our study aimed to estimate BV in athletes for metabolism and growth-related biomarkers involved in the Athlete Biological Passport (ABP), by 2 different statistical models. METHODS Thirty triathletes were sampled monthly for 11 months. The samples were analyzed for human growth hormone (hGH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), insulin, and N-terminal propeptide of type III procollagen (P-III-NP) by immunoassay. Bayesian and ANOVA methods were applied to estimate within-subject (CVI) and between-subject BV. RESULTS CVI estimates ranged from 7.8% for IGFBP-3 to 27.0% for insulin, when derived by the Bayesian method. The 2 models gave similar results, except for P-III-NP. Data were heterogeneously distributed for P-III-NP for the overall population and in females for IGF-1 and IGFBP-3. BV components were not estimated for hGH due to lack of steady state. The index of individuality was below 0.6 for all measurands, except for insulin. CONCLUSIONS In an athlete population, to apply a common CVI for insulin would be appropriate, but for IGF-1 and IGFBP-3 gender-specific estimates should be applied. P-III-NP data were heterogeneously distributed and using a mean CVI may not be representative for the population. The high degree of individuality for IGF-1, IGFBP-3, and P-III-NP makes them good candidates to be interpreted through reference change values and the ABP.
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Affiliation(s)
- Isabel Moreno-Parro
- Department of Laboratory Medicine, La Paz University Hospital, Madrid, Spain
- IdiPaz-Hospital La Paz Institute for Health Research, Madrid, Spain
| | - Jorge Diaz-Garzon
- Department of Laboratory Medicine, La Paz University Hospital, Madrid, Spain
- IdiPaz-Hospital La Paz Institute for Health Research, Madrid, Spain
| | - Aasne K Aarsand
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
- Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Sverre Sandberg
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
- Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
| | - Reid Aikin
- World Anti-Doping Agency (WADA), Montreal, Quebec, Canada
| | - Tristan Equey
- World Anti-Doping Agency (WADA), Montreal, Quebec, Canada
| | - Juan José Ríos-Blanco
- IdiPaz-Hospital La Paz Institute for Health Research, Madrid, Spain
- Department of Internal Medicine, La Paz University Hospital, Madrid, Spain
| | - Antonio Buño Soto
- Department of Laboratory Medicine, La Paz University Hospital, Madrid, Spain
- IdiPaz-Hospital La Paz Institute for Health Research, Madrid, Spain
| | - Pilar Fernandez-Calle
- Department of Laboratory Medicine, La Paz University Hospital, Madrid, Spain
- IdiPaz-Hospital La Paz Institute for Health Research, Madrid, Spain
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Diaz-Garzon J, Itkonen O, Aarsand AK, Sandberg S, Coskun A, Carobene A, Jonker N, Bartlett WA, Buño A, Fernandez-Calle P. Biological variation of inflammatory and iron metabolism markers in high-endurance recreational athletes; are these markers useful for athlete monitoring? Clin Chem Lab Med 2024; 62:844-852. [PMID: 38062926 DOI: 10.1515/cclm-2023-1071] [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: 09/25/2023] [Accepted: 11/21/2023] [Indexed: 04/05/2024]
Abstract
OBJECTIVES To deliver biological variation (BV) data for serum hepcidin, soluble transferrin receptor (sTfR), erythropoietin (EPO) and interleukin 6 (IL-6) in a population of well-characterized high-endurance athletes, and to evaluate the potential influence of exercise and health-related factors on the BV. METHODS Thirty triathletes (15 females) were sampled monthly (11 months). All samples were analyzed in duplicate and BV estimates were delivered by Bayesian and ANOVA methods. A linear mixed model was applied to study the effect of factors related to exercise, health, and sampling intervals on the BV estimates. RESULTS Within-subject BV estimates (CVI) were for hepcidin 51.9 % (95 % credibility interval 46.9-58.1), sTfR 10.3 % (8.8-12) and EPO 27.3 % (24.8-30.3). The mean concentrations were significantly different between sex, but CVI estimates were similar and not influenced by exercise, health-related factors, or sampling intervals. The data were homogeneously distributed for EPO but not for hepcidin or sTfR. IL-6 results were mostly below the limit of detection. Factors related to exercise, health, and sampling intervals did not influence the BV estimates. CONCLUSIONS This study provides, for the first time, BV data for EPO, derived from a cohort of well-characterized endurance athletes and indicates that EPO is a good candidate for athlete follow-up. The application of the Bayesian method to deliver BV data illustrates that for hepcidin and sTfR, BV data are heterogeneously distributed and using a mean BV estimate may not be appropriate when using BV data for laboratory and clinical applications.
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Affiliation(s)
- Jorge Diaz-Garzon
- Laboratory Medicine Department, La Paz University Hospital, Madrid, Spain
| | - Outi Itkonen
- Endocrinology and Metabolism Laboratory, Helsinki University Hospital, Helsinki, Finland
| | - Aasne K Aarsand
- Department of Medical Biochemistry and Pharmacology, Norwegian Porphyria Centre, Haukeland University Hospital, Bergen, Norway
- Norwegian Organization for Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Sverre Sandberg
- Department of Medical Biochemistry and Pharmacology, Norwegian Porphyria Centre, Haukeland University Hospital, Bergen, Norway
- Norwegian Organization for Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Abdurrahman Coskun
- Department of Medical Biochemistry Atasehir, School of Medicine, Acibadem Mehmet Ali Aydınlar University, Istanbul, Türkiye
| | - Anna Carobene
- Laboratory Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Niels Jonker
- Certe, Wilhelmina Ziekenhuis Assen, Assen, The Netherlands
| | - William A Bartlett
- Undergraduate Teaching, School of Medicine, University of Dundee, Dundee, Scotland
| | - Antonio Buño
- Laboratory Medicine Department, La Paz University Hospital, Madrid, Spain
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Tong WW, Tong GH, Yang MH, Qin XS. Age and seasonal variation and establishment of reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry. Nutrition 2021; 95:111490. [PMID: 35026483 DOI: 10.1016/j.nut.2021.111490] [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: 06/16/2021] [Revised: 08/18/2021] [Accepted: 09/01/2021] [Indexed: 12/12/2022]
Abstract
OBJECTIVES We aimed to establish reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry to improve the diagnosis of vitamin deficiency and outcomes of associated conditions. METHODS In this retrospective analysis of 24 810 specimens, we aimed to examine sex-, age-, and season-related variations in vitamin levels in different groups, set reference-value intervals for vitamin levels, and evaluate these reference values against those recommended by manufacturers. RESULTS Levels of vitamins B3, B5, B6, B7, and B12 were higher, and those of vitamins B2, B9, and C were lower, in men than in women. There were seasonal variations in levels of vitamins B1, B3, B5, B6, B9, B12, and C. Levels of vitamins B1, B2, B3, B5, B6, B7, B9, and C differed across age groups; vitamin B1 displayed significant differences between ages 0 to 14 years and adults compared with reference change values. The lower limits of vitamins B1 (ages 15-100 y), B2, B3, B7, and C were lower, and that of vitamin B5 was higher, than the recommended reference values. Finally, the upper limits of vitamins B1, B3, B5, B6, and B7 were lower than the recommended values. CONCLUSIONS For values obtained using liquid chromatography tandem mass spectrometry, the lower limits of reference intervals for vitamins B1 (ages 15-100 y), B2, B3, B7, and C should be lowered, that of vitamin B5 should be raised, and the upper limits of reference intervals for vitamins B1, B3, B5, B6, and B7 should be lowered.
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Affiliation(s)
- Wei-Wei Tong
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Guang-Hui Tong
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Meng-Han Yang
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xiao-Song Qin
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Shenyang, China.
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Aarsand AK, Kristoffersen AH, Sandberg S, Støve B, Coşkun A, Fernandez-Calle P, Díaz-Garzón J, Guerra E, Ceriotti F, Jonker N, Røraas T, Carobene A. The European Biological Variation Study (EuBIVAS): Biological Variation Data for Coagulation Markers Estimated by a Bayesian Model. Clin Chem 2021; 67:1259-1270. [PMID: 34387652 DOI: 10.1093/clinchem/hvab100] [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: 02/05/2021] [Accepted: 04/19/2021] [Indexed: 11/13/2022]
Abstract
BACKGROUND For biological variation (BV) data to be safely used, data must be reliable and relevant to the population in which they are applied. We used samples from the European Biological Variation Study (EuBIVAS) to determine BV of coagulation markers by a Bayesian model robust to extreme observations and used the derived within-participant BV estimates [CVP(i)] to assess the applicability of the BV estimates in clinical practice. METHOD Plasma samples were drawn from 92 healthy individuals for 10 consecutive weeks at 6 European laboratories and analyzed in duplicate for activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen, D-dimer, antithrombin (AT), protein C, protein S free, and factor VIII (FVIII). A Bayesian model with Student t likelihoods for samples and replicates was applied to derive CVP(i) and predicted BV estimates with 95% credibility intervals. RESULTS For all markers except D-dimer, CVP(i) were homogeneously distributed in the overall study population or in subgroups. Mean within-subject estimates (CVI) were <5% for APTT, PT, AT, and protein S free, <10% for protein C and FVIII, and <12% for fibrinogen. For APTT, protein C, and protein S free, estimates were significantly lower in men than in women ≤50 years. CONCLUSION For most coagulation markers, a common CVI estimate for men and women is applicable, whereas for APTT, protein C, and protein S free, sex-specific reference change values should be applied. The use of a Bayesian model to deliver individual CVP(i) allows for improved interpretation and application of the data.
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Affiliation(s)
- Aasne K Aarsand
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.,Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Ann Helen Kristoffersen
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.,Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Sverre Sandberg
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.,Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway.,Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
| | - Bård Støve
- Department of Mathematics, University of Bergen, Bergen, Norway
| | - Abdurrahman Coşkun
- Department of Medical Biochemistry, Acibadem Mehmet Ali Aydınlar University School of Medicine, Atasehir, Istanbul, Turkey
| | - Pilar Fernandez-Calle
- Department of Laboratory Medicine, Hospital Universitario La Paz, Madrid, Spain.,Analytical Quality Commission of Spanish Society of Laboratory Medicine (SEQCML), Madrid, Spain
| | - Jorge Díaz-Garzón
- Department of Laboratory Medicine, Hospital Universitario La Paz, Madrid, Spain.,Analytical Quality Commission of Spanish Society of Laboratory Medicine (SEQCML), Madrid, Spain
| | - Elena Guerra
- Laboratory Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Ferruccio Ceriotti
- Central Laboratory, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Niels Jonker
- Certe, Wilhelmina Ziekenhuis Assen, Assen, the Netherlands
| | - Thomas Røraas
- Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Anna Carobene
- Laboratory Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
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Reference change values based on uncertainty models. Clin Biochem 2020; 80:31-41. [DOI: 10.1016/j.clinbiochem.2020.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 03/28/2020] [Accepted: 03/28/2020] [Indexed: 11/17/2022]
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Borai A, Khalil H, Alghamdi B, Alhamdi R, Ali N, Bahijri S, Ferns G. The pre-analytical stability of 25-hydroxyvitamin D: Storage and mixing effects. J Clin Lab Anal 2019; 34:e23037. [PMID: 31587378 PMCID: PMC7031638 DOI: 10.1002/jcla.23037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/17/2019] [Accepted: 08/19/2019] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND There is an increasing demand for serum 25-OH VitD testing globally, and this has led to the greater use of automated immunoassays. These may be more prone to non-specific interference, that is thought to be related to pre-analytical stability of biological samples. We have investigated the changes in serum 25-OH VitD concentrations that are caused by storage and mixing conditions, and if such changes are statistical, or clinically important. METHODS Blood samples were collected into plain tubes from 31 healthy donors. After separation, serum samples were stored at -20°C and analysis was carried out with and without mixing (vortexing) at different time intervals of days (0, 1, 2, 3, 4, 5, 15, and 30). All samples were analyzed using a chemiluminescent immunoassay. RESULTS Mean serum 25-OH VitD concentrations for subsequent days of storage compared with day 0 showed a significant time effect (P < .05) except for the samples on day 1 (P = .654) in non-vortexed samples and day 2 (P = .087), 5 (P = .118) and 30 (P = .118) in vortexed samples. Comparing values for vortexed and non-vortexed samples on the same day, serum 25-OH VitD showed a significant difference on days 1 (P = .003), 4 (P = .037), 5 (P = .002), and 30 (P = .025). However, the maximum change value was 8.85% which was less than the known total allowable error (TEa) and reference change value (RCV) for serum 25-OH VitD. CONCLUSION 25-OH VitD is pre-analytically stable after long-term sample storage at -20°C and can be analyzed without vortexing. This may be beneficial for both research and diagnostic laboratories.
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Affiliation(s)
- Anwar Borai
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Pathology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Haitham Khalil
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Pathology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Basma Alghamdi
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Pathology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Raghad Alhamdi
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Pathology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Najwa Ali
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Pathology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Suhad Bahijri
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Gordon Ferns
- Division of Medical Education, Brighton and Sussex Medical School, Mayfield House, Brighton, UK
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Røraas T, Sandberg S, Aarsand AK, Støve B. A Bayesian Approach to Biological Variation Analysis. Clin Chem 2019; 65:995-1005. [DOI: 10.1373/clinchem.2018.300145] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/13/2019] [Indexed: 11/06/2022]
Abstract
Abstract
BACKGROUND
Biological variation (BV) data have many applications for diagnosing and monitoring disease. The standard statistical approaches for estimating BV are sensitive to “noisy data” and assume homogeneity of within-participant CV. Prior knowledge about BV is mostly ignored. The aims of this study were to develop Bayesian models to calculate BV that (a) are robust to “noisy data,” (b) allow heterogeneity in the within-participant CVs, and (c) take advantage of prior knowledge.
METHOD
We explored Bayesian models with different degrees of robustness using adaptive Student t distributions instead of the normal distributions and when the possibility of heterogeneity of the within-participant CV was allowed. Results were compared to more standard approaches using chloride and triglyceride data from the European Biological Variation Study.
RESULTS
Using the most robust Bayesian approach on a raw data set gave results comparable to a standard approach with outlier assessments and removal. The posterior distribution of the fitted model gives access to credible intervals for all parameters that can be used to assess reliability. Reliable and relevant priors proved valuable for prediction.
CONCLUSIONS
The recommended Bayesian approach gives a clear picture of the degree of heterogeneity, and the ability to crudely estimate personal within-participant CVs can be used to explore relevant subgroups. Because BV experiments are expensive and time-consuming, prior knowledge and estimates should be considered of high value and applied accordingly. By including reliable prior knowledge, precise estimates are possible even with small data sets.
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Affiliation(s)
- Thomas Røraas
- Norwegian Organisation for Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Sverre Sandberg
- Norwegian Organisation for Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway
- Department of Global Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, Norway
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Aasne K Aarsand
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Bård Støve
- Department of Mathematics, University of Bergen, Norway
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9
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Lanuti P, Simeone P, Rotta G, Almici C, Avvisati G, Azzaro R, Bologna G, Budillon A, Di Cerbo M, Di Gennaro E, Di Martino ML, Diodato A, Doretto P, Ercolino E, Falda A, Gregorj C, Leone A, Losa F, Malara N, Marini M, Mastroroberto P, Mollace V, Morelli M, Muggianu E, Musolino G, Neva A, Pierdomenico L, Pinna S, Piovani G, Roca MS, Russo D, Scotti L, Tirindelli MC, Trunzo V, Venturella R, Vitagliano C, Zullo F, Marchisio M, Miscia S. A standardized flow cytometry network study for the assessment of circulating endothelial cell physiological ranges. Sci Rep 2018; 8:5823. [PMID: 29643468 PMCID: PMC5895616 DOI: 10.1038/s41598-018-24234-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/28/2018] [Indexed: 12/18/2022] Open
Abstract
Circulating endothelial cells (CEC) represent a restricted peripheral blood (PB) cell subpopulation with high potential diagnostic value in many endothelium-involving diseases. However, whereas the interest in CEC studies has grown, the standardization level of their detection has not. Here, we undertook the task to align CEC phenotypes and counts, by standardizing a novel flow cytometry approach, within a network of six laboratories. CEC were identified as alive/nucleated/CD45negative/CD34bright/CD146positive events and enumerated in 269 healthy PB samples. Standardization was demonstrated by the achievement of low inter-laboratory Coefficients of Variation (CVL), calculated on the basis of Median Fluorescence Intensity values of the most stable antigens that allowed CEC identification and count (CVL of CD34bright on CEC ~ 30%; CVL of CD45 on Lymphocytes ~ 20%). By aggregating data acquired from all sites, CEC numbers in the healthy population were captured (medianfemale = 9.31 CEC/mL; medianmale = 11.55 CEC/mL). CEC count biological variability and method specificity were finally assessed. Results, obtained on a large population of donors, demonstrate that the established procedure might be adopted as standardized method for CEC analysis in clinical and in research settings, providing a CEC physiological baseline range, useful as starting point for their clinical monitoring in endothelial dysfunctions.
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Affiliation(s)
- Paola Lanuti
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
| | - Pasquale Simeone
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
| | | | - Camillo Almici
- Laboratory for Stem Cells Manipulation and Cryopreservation, Department of Transfusion Medicine, Spedali Civili of Brescia, Brescia, Italy
| | - Giuseppe Avvisati
- Hematology, Stem Cell Transplantation, Transfusion Medicine and Cellular Therapy, Department of Medicine, Campus Bio-Medico University Hospital, Roma, Italy
| | - Rosa Azzaro
- Transfusion Service, Department of Hematology-Oncology and Stem Cell Transplantation Unit, Napoli, Italy
| | - Giuseppina Bologna
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
| | - Alfredo Budillon
- Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori- IRCCS G. Pascale, Napoli, Italy
| | - Melania Di Cerbo
- Hematology, Stem Cell Transplantation, Transfusion Medicine and Cellular Therapy, Department of Medicine, Campus Bio-Medico University Hospital, Roma, Italy
| | - Elena Di Gennaro
- Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori- IRCCS G. Pascale, Napoli, Italy
| | - Maria Luisa Di Martino
- Unit of Internal Medicine, Allergy and Clinical Immunology, Department of Medical Sciences "M. Aresu", University of Cagliari Monserrato, Cagliari, Italy
| | - Annamaria Diodato
- Transfusion Service, Department of Hematology-Oncology and Stem Cell Transplantation Unit, Napoli, Italy
| | - Paolo Doretto
- Clinical Pathology Laboratory, Department of Laboratory Medicine, AAS5, Pordenone Hospital, Pordenone, Italy
| | - Eva Ercolino
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
| | - Alessandra Falda
- Clinical Pathology Laboratory, Department of Laboratory Medicine, AAS5, Pordenone Hospital, Pordenone, Italy
| | - Chiara Gregorj
- Hematology, Stem Cell Transplantation, Transfusion Medicine and Cellular Therapy, Department of Medicine, Campus Bio-Medico University Hospital, Roma, Italy
| | - Alessandra Leone
- Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori- IRCCS G. Pascale, Napoli, Italy
| | - Francesca Losa
- Unit of Internal Medicine, Allergy and Clinical Immunology, Department of Medical Sciences "M. Aresu", University of Cagliari Monserrato, Cagliari, Italy
| | - Natalia Malara
- Department of Health Science University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Mirella Marini
- Laboratory for Stem Cells Manipulation and Cryopreservation, Department of Transfusion Medicine, Spedali Civili of Brescia, Brescia, Italy
| | - Pasquale Mastroroberto
- Department of Experimental and Clinical Medicine, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Vincenzo Mollace
- Department of Health Science University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Michele Morelli
- Department of Obstetrics and Gynecology, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Emma Muggianu
- Unit of Internal Medicine, Allergy and Clinical Immunology, Department of Medical Sciences "M. Aresu", University of Cagliari Monserrato, Cagliari, Italy
| | - Giuseppe Musolino
- Department of Experimental and Clinical Medicine, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Arabella Neva
- Laboratory for Stem Cells Manipulation and Cryopreservation, Department of Transfusion Medicine, Spedali Civili of Brescia, Brescia, Italy
| | - Laura Pierdomenico
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
| | - Silvia Pinna
- Unit of Internal Medicine, Allergy and Clinical Immunology, Department of Medical Sciences "M. Aresu", University of Cagliari Monserrato, Cagliari, Italy
| | - Giovanna Piovani
- Department Molecular Medicine and Translational, University of Brescia, Brescia, Italy
| | - Maria Serena Roca
- Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori- IRCCS G. Pascale, Napoli, Italy
| | - Domenico Russo
- Unit of Blood Diseases and Stem Cell Transplantation, University of Brescia, Brescia, Italy
| | - Lorenza Scotti
- Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milano, Italy
| | - Maria Cristina Tirindelli
- Hematology, Stem Cell Transplantation, Transfusion Medicine and Cellular Therapy, Department of Medicine, Campus Bio-Medico University Hospital, Roma, Italy
| | - Valentina Trunzo
- Department of Health Science University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Roberta Venturella
- Department of Obstetrics and Gynecology, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Carlo Vitagliano
- Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori- IRCCS G. Pascale, Napoli, Italy
| | - Fulvio Zullo
- Department of Obstetrics and Gynecology, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Marco Marchisio
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy.
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy.
| | - Sebastiano Miscia
- Department of Medicine and Aging Sciences, University "G.d'Annunzio", Chieti-Pescara, Italy
- Centre on Aging Sciences and Translational Medicine (Ce.S.I.-Me.T.), University "G.d'Annunzio", Chieti-Pescara, Italy
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Camacho OM, Sommarström J, Prasad K, Cunningham A. Reference change values in concentrations of urinary and salivary biomarkers of exposure and mouth level exposure in individuals participating in an ambulatory smoking study. Pract Lab Med 2016; 5:47-56. [PMID: 28856204 PMCID: PMC5574496 DOI: 10.1016/j.plabm.2016.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 05/12/2016] [Accepted: 05/16/2016] [Indexed: 01/12/2023] Open
Abstract
Background Modified-risk tobacco products (MRTPs) are being developed that may contribute to tobacco harm reduction. To support reduced exposure or risk claims, a scientific framework needs to be developed to assess the validity of claims and monitor consumers after product launch. We calculated reference change values (RCVs) for biomarker of exposure (BoE): salivary cotinine and hydroxycotinine; and urinary total nicotine equivalents, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and creatinine. Mouth-level exposure (MLE) to nicotine and tar were also recorded in an ambulatory setting to characterise variation among smokers in their everyday environment. Methods This non-residential, observational study was conducted over 3.5 years across 10 sites in Germany. Smokers of the same commercial 10 mg ISO tar product were included in the study (N=1011). Urine samples, questionnaires and cigarette filters were collected every 6 months for a total of seven timepoints. Results Greater variability in BoEs was observed compared with confined clinical studies. Gaussian distributed data showed 2-sided values over 100%, which are uninformative for decreases. The proportion of significant changes increased slightly among switchers, probably as a result of additional variability due to the range of products used post-switching. Overall proportions of changes remained small, consistent with literature reporting that when switching to a different tar yield cigarette, smokers partially compensate by changing their smoking behaviour. Conclusion Variability estimates and RCVs can be useful for monitoring subjects' BoE and MLE endpoints in longitudinal smoking studies where subjects are followed in their own environment and to aid sample size calculation of studies involving these endpoints.
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11
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Cheuvront SN, Kenefick RW. Dehydration: physiology, assessment, and performance effects. Compr Physiol 2014; 4:257-85. [PMID: 24692140 DOI: 10.1002/cphy.c130017] [Citation(s) in RCA: 260] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This article provides a comprehensive review of dehydration assessment and presents a unique evaluation of the dehydration and performance literature. The importance of osmolality and volume are emphasized when discussing the physiology, assessment, and performance effects of dehydration. The underappreciated physiologic distinction between a loss of hypo-osmotic body water (intracellular dehydration) and an iso-osmotic loss of body water (extracellular dehydration) is presented and argued as the single most essential aspect of dehydration assessment. The importance of diagnostic and biological variation analyses to dehydration assessment methods is reviewed and their use in gauging the true potential of any dehydration assessment method highlighted. The necessity for establishing proper baselines is discussed, as is the magnitude of dehydration required to elicit reliable and detectable osmotic or volume-mediated compensatory physiologic responses. The discussion of physiologic responses further helps inform and explain our analysis of the literature suggesting a ≥ 2% dehydration threshold for impaired endurance exercise performance mediated by volume loss. In contrast, no clear threshold or plausible mechanism(s) support the marginal, but potentially important, impairment in strength, and power observed with dehydration. Similarly, the potential for dehydration to impair cognition appears small and related primarily to distraction or discomfort. The impact of dehydration on any particular sport skill or task is therefore likely dependent upon the makeup of the task itself (e.g., endurance, strength, cognitive, and motor skill).
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Affiliation(s)
- Samuel N Cheuvront
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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12
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Metwalli AR, Rosner IL, Cullen J, Chen Y, Brand T, Brassell SA, Lesperance J, Porter C, Sterbis J, McLeod DG. Elevated alkaline phosphatase velocity strongly predicts overall survival and the risk of bone metastases in castrate-resistant prostate cancer. Urol Oncol 2014; 32:761-8. [PMID: 24929891 DOI: 10.1016/j.urolonc.2014.03.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/26/2014] [Accepted: 03/29/2014] [Indexed: 11/17/2022]
Abstract
OBJECTIVES In patients with a rising prostate-specific antigen (PSA) level during treatment with androgen deprivation therapy, identification of men who progress to bone metastasis and death remains problematic. Accurate risk stratification models are needed to better predict risk for bone metastasis and death among patients with castration-resistant prostate cancer (CRPC). This study evaluates whether alkaline phosphatase (AP) kinetics predicts bone metastasis and death in patients with CRPC. METHODS AND MATERIALS A retrospective cohort study of 9,547 patients who underwent treatment for prostate cancer was conducted using the Center for Prostate Disease Research Multi-center National Database. From the entire cohort, 347 were found to have CRPC and, of those, 165 had 2 or more AP measurements during follow-up. To determine the AP velocity (APV), the slope of the linear regression line of all AP values was plotted over time. Rapid APV was defined as the uppermost quartile of APV values, which was found to be ≥6.3 IU/l/y. CRPC was defined as 2 consecutive rising PSA values after achieving a PSA nadir<4 ng/ml and documented testosterone values less than 50 ng/dl. The primary study outcomes included bone metastasis-free survival (BMFS) and overall survival (OS). RESULTS Rapid APV and PSA doubling time (PSADT) less than 10 months were strong predictors of both BMFS and OS in a multivariable analysis. Faster PSADT was a stronger predictor for BMFS (odds ratio [OR] = 12.1, P<0.0001 vs. OR = 2.7, P = 0.011), whereas rapid APV was a stronger predictor of poorer OS (OR = 5.11, P = 0.0001 vs. OR = 3.98, P = 0.0034). In those with both a rapid APV and a faster PSADT, the odds of developing bone metastasis and death exceeded 50%. CONCLUSION APV is an independent predictor of OS and BMFS in patients with CRPC. APV, in conjunction with PSA-based clinical parameters, may be used to better identify patients with CRPC who are at the highest risk of metastasis and death. These findings need validation in prospective studies.
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Affiliation(s)
- Adam R Metwalli
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD.
| | - Inger L Rosner
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | - Jennifer Cullen
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | - Yongmei Chen
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | - Timothy Brand
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | | | - James Lesperance
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | | | - Joseph Sterbis
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
| | - David G McLeod
- Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, MD
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Siest G, Henny J, Gräsbeck R, Wilding P, Petitclerc C, Queraltó JM, Hyltoft Petersen P. The theory of reference values: an unfinished symphony. Clin Chem Lab Med 2014. [PMID: 23183761 DOI: 10.1515/cclm-2012-0682] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The history of the theory of reference values can be written as an unfinished symphony. The first movement, allegro con fuoco, played from 1960 to 1980: a mix of themes devoted to the study of biological variability (intra-, inter-individual, short- and long-term), preanalytical conditions, standardization of analytical methods, quality control, statistical tools for deriving reference limits, all of them complex variations developed on a central melody: the new concept of reference values that would replace the notion of normality whose definition was unclear. Additional contributions (multivariate reference values, use of reference limits from broad sets of patient data, drug interferences) conclude the movement on the variability of laboratory tests. The second movement, adagio, from 1980 to 2000, slowly develops and implements initial works. International and national recommendations were published by the IFCC-LM (International Federation of Clinical Chemistry and Laboratory Medicine) and scientific societies [French (SFBC), Spanish (SEQC), Scandinavian societies…]. Reference values are now topics of many textbooks and of several congresses, workshops, and round tables that are organized all over the world. Nowadays, reference values are part of current practice in all clinical laboratories, but not without difficulties, particularly for some laboratories to produce their own reference values and the unsuitability of the concept with respect to new technologies such as HPLC, GCMS, and PCR assays. Clinicians through consensus groups and practice guidelines have introduced their own tools, the decision limits, likelihood ratios and Reference Change Value (RCV), creating confusion among laboratorians and clinicians in substituting reference values and decision limits in laboratory reports. The rapid development of personalized medicine will eventually call for the use of individual reference values. The beginning of the second millennium is played allegro ma non-troppo from 2000 to 2012: the theory of reference values is back into fashion. The need to revise the concept is emerging. The manufacturers make a friendly pressure to facilitate the integration of Reference Intervals (RIs) in their technical documentation. Laboratorians are anxiously awaiting the solutions for what to do. The IFCC-LM creates Reference Intervals and Decision Limits Committee (C-RIDL) in 2005. Simultaneously, a joint working group IFCC-CLSI is created on the same topic. In 2008 the initial recommendations of IFCC-LM are revised and new guidelines are published by the Clinical and Laboratory Standards Institute (CLSI C28-A3). Fundamentals of the theory of reference values are not changed, but new avenues are explored: RIs transference, multicenter reference intervals, and a robust method for deriving RIs from small number of subjects. Concomitantly, other statistical methods are published such as bootstraps calculation and partitioning procedures. An alternative to recruiting healthy subjects proposes the use of biobanks conditional to the availability of controlled preanalytical conditions and of bioclinical data. The scope is also widening to include veterinary biology! During the early 2000s, several groups proposed the concept of 'Universal RIs' or 'Global RIs'. Still controversial, their applications await further investigations. The fourth movement, finale: beyond the methodological issues (statistical and analytical essentially), important questions remain unanswered. Do RIs intervene appropriately in medical decision-making? Are RIs really useful to the clinicians? Are evidence-based decision limits more appropriate? It should be appreciated that many laboratory tests represent a continuum that weakens the relevance of RIs. In addition, the boundaries between healthy and pathological states are shady areas influenced by many biological factors. In such a case the use of a single threshold is questionable. Wherever it will apply, individual reference values and reference change values have their place. A variation on an old theme! It is strange that in the period of personalized medicine (that is more stratified medicine), the concept of reference values which is based on stratification of homogeneous subgroups of healthy people could not be discussed and developed in conjunction with the stratification of sick patients. That is our message for the celebration of the 50th anniversary of Clinical Chemistry and Laboratory Medicine. Prospects are broad, enthusiasm is not lacking: much remains to be done, good luck for the new generations!
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Affiliation(s)
- Gerard Siest
- University of Lorraine, Research Unit EA 4373, Génétique Cardiovasculaire, Nancy, France.
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Borai A, Livingstone C, Ferns G. Reference change values for insulin and insulin-like growth factor binding protein-1 (IGFBP-1) in individuals with varying degrees of glucose tolerance. Scandinavian Journal of Clinical and Laboratory Investigation 2013; 73:274-8. [DOI: 10.3109/00365513.2013.771281] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Cheuvront SN, Kenefick RW, Charkoudian N, Sawka MN. Physiologic basis for understanding quantitative dehydration assessment. Am J Clin Nutr 2013; 97:455-62. [PMID: 23343973 DOI: 10.3945/ajcn.112.044172] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dehydration (body water deficit) is a physiologic state that can have profound implications for human health and performance. Unfortunately, dehydration can be difficult to assess, and there is no single, universal gold standard for decision making. In this article, we review the physiologic basis for understanding quantitative dehydration assessment. We highlight how phenomenologic interpretations of dehydration depend critically on the type (dehydration compared with volume depletion) and magnitude (moderate compared with severe) of dehydration, which in turn influence the osmotic (plasma osmolality) and blood volume-dependent compensatory thresholds for antidiuretic and thirst responses. In particular, we review new findings regarding the biological variation in osmotic responses to dehydration and discuss how this variation can help provide a quantitative and clinically relevant link between the physiology and phenomenology of dehydration. Practical measures with empirical thresholds are provided as a starting point for improving the practice of dehydration assessment.
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Houwert AC, Lock MTWT, Lentjes EGWM. Alphafetoprotein in the Dutch External Quality Assurance programme: a need for improvement. Ann Clin Biochem 2012; 49:273-6. [DOI: 10.1258/acb.2011.011046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background Elevated alphafetoprotein (AFP) concentrations may result from a variety of clinical conditions, but their role as an important tumour marker has been well established. There may be differences in AFP values due to laboratories using different methods, even though most methods have been calibrated with the same international standard (WHO IS 72/225). Therefore it is important to know the analytical performance of the various methods in relation to the analytical requirements for AFP measurement. Methods Annually, from January 2005 to July 2010, the results were analysed from the 65–75 laboratories that took part in the AFP survey of the External Quality Assurance programme of the Foundation Quality Control Medical Laboratories (the SKML/Binding Analysis) in the Netherlands. Results The Elecsys/Modular (36%) and the Immulite 2000/2500 (29%) are the methods used most. The methods show, on average, up to 15% positive and 12% negative bias, compared with the all-laboratory trimmed mean. Of the laboratories using the Immulite or the Elecsys/Modular analyser, over 70% show sufficient analytical performance to meet the Fraser criterion for method imprecision. Of the laboratories using a different method, over 50% do not meet this criterion. Conclusions AFP immunoassays suffer from method bias, even though all methods have been calibrated with the same international standard. Some of the methods used show insufficient performance.
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Affiliation(s)
- A Carolien Houwert
- Department of Urology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht
| | - M T W Tycho Lock
- Department of Urology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht
| | - Eef G W M Lentjes
- Section Endocrinology, Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
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Padró-Miquel A, Rigo-Bonnin R, Fuentes-Arderiu X. Significance of a change between two consecutive measured values. Scandinavian Journal of Clinical and Laboratory Investigation 2012; 72:169-72. [DOI: 10.3109/00365513.2011.637575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Trapé J, Montesinos J, Franquesa J, Sala M, Fígols C, Miguel A, Domenech M. Determination of the biological variation of S100β and lactate dehydrogenase in disease-free patients with malignant melanoma. Clin Chem Lab Med 2011; 50:927-9. [PMID: 22117782 DOI: 10.1515/cclm.2012.799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 10/30/2011] [Indexed: 11/15/2022]
Abstract
BACKGROUND Biological variation is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements. The aim of this study was to determine the biological variation for S100β and lactate dehydrogenase in patients diagnosed with malignant melanoma but without evidence of disease recurrence. METHODS The biological variation of S100β and lactate dehydrogenase was estimated from a mean of four consecutive measurements in 32 patients diagnosed with malignant melanoma but without evidence of disease recurrence, 3 months after tumor resection or 4 months after finishing adjuvant treatment. The mean sampling interval was 3 months. RESULTS Mean concentrations of S100β and lactate dehydrogenase were 0.0557 μg/L and 6.3 μkat/L, respectively. Between-run analytical variation was 3.5% at 0.181 μg/L for S100β and 3.5% at 2.83 μkat/L for lactate dehydrogenase. Biological variations obtained for S100β and lactate dehydrogenase were 14.2% and 8.2%, respectively. The analytical goals (defined as 50% of biological variation) were 7.1% for S100β and 4.1% for lactate dehydrogenase. CONCLUSIONS The estimation of biological variation allows us to calculate analytical goals and reference change values. These are necessary tools for the correct interpretation of serial measurements in patient follow-up.
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Affiliation(s)
- Jaume Trapé
- Service of Clinical Chemistry, Department of Biological Diagnosis, Althaia, Xarxa Assistencial de Manresa, Manresa, Spain.
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Cooper G, DeJonge N, Ehrmeyer S, Yundt-Pacheco J, Jansen R, Ricós C, Plebani M. Collective opinion paper on findings of the 2010 convocation of experts on laboratory quality. Clin Chem Lab Med 2011; 49:793-802. [PMID: 21366504 DOI: 10.1515/cclm.2011.149] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
As a part of a series of yearly meeting, in May 2010 over 40 medical laboratory opinion leaders, pathologists, clinical biochemists and physicians from Europe, Israel and South Africa gathered together in Bardolino, Italy to discuss issues and current challenges for laboratory medicine, including a) the use of biological variation 10 years after the Stockholm Conference; b) achieving quality in point-of-care testing; c) assessing risk and controlling sources of error in the laboratory; d) determining the appropriate frequency of quality control; and f) putting laboratory medicine at the core of patient care. The intended goal of the convocation was to give laboratory professionals from different countries and backgrounds the opportunity to share ideas, concerns and experiences in previously mentioned areas of interest. This paper provide a synopsis of the reports from each working group.
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Cheuvront SN, Ely BR, Kenefick RW, Sawka MN. Biological variation and diagnostic accuracy of dehydration assessment markers. Am J Clin Nutr 2010; 92:565-73. [PMID: 20631205 DOI: 10.3945/ajcn.2010.29490] [Citation(s) in RCA: 234] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Well-recognized markers for static (one time) or dynamic (monitoring over time) dehydration assessment have not been rigorously tested for their usefulness in clinical, military, and sports medicine communities. OBJECTIVE This study evaluated the components of biological variation and the accuracy of potential markers in plasma, urine, saliva, and body mass (B(m)) for static and dynamic dehydration assessment. DESIGN We studied 18 healthy volunteers (13 men and 5 women) while carefully controlling hydration and numerous preanalytic factors. Biological variation was determined over 3 consecutive days by using published methods. Atypical values based on statistical deviations from a homeostatic set point were examined. Measured deviations in body fluid were produced by using a separate, prospective dehydration experiment and evaluated by receiver operating characteristic (ROC) analysis to quantify diagnostic accuracy. RESULTS All dehydration markers displayed substantial individuality and one-half of the dehydration markers displayed marked heterogeneity of intraindividual variation. Decision levels for all dehydration markers were within one SD of the ROC criterion values, and most levels were nearly identical to the prospective group means after volunteers were dehydrated by 1.8-7.0% of B(m). However, only plasma osmolality (P(osm)) showed statistical promise for use in the static dehydration assessment. A diagnostic decision level of 301 plusmn 5 mmol/kg was proposed. Reference change values of 9 mmol/kg (P(osm)), 0.010 [urine specific gravity (U(sg))], and 2.5% change in B(m) were also statistically valid for dynamic dehydration assessment at the 95% probability level. CONCLUSIONS P(osm) is the only useful marker for static dehydration assessment. P(osm), U(sg), and B(m) are valid markers in the setting of dynamic dehydration assessment.
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Affiliation(s)
- Samuel N Cheuvront
- US Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA.
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Trapé J, Franquesa J, Sala M, Domenech M, Montesinos J, Catot S, Buxó J, Casado E, Fígols C, Harillo S, Galobart J, Bella M. Determination of biological variation of α-fetoprotein and choriogonadotropin (β chain) in disease-free patients with testicular cancer. Clin Chem Lab Med 2010; 48:1799-801. [DOI: 10.1515/cclm.2010.343] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Omar F, van der Watt GF, Pillay TS. Reference change values: how useful are they? J Clin Pathol 2008; 61:426-7. [DOI: 10.1136/jcp.2007.054833] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Develter M, Blanckaert N, Komárek A, Bossuyt X. Can Heparin Plasma Be Used instead of Serum for Nephelometric Analysis of Serum Proteins? Clin Chem 2006; 52:1609-10. [PMID: 16873302 DOI: 10.1373/clinchem.2006.071357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Comin-Anduix B, Gualberto A, Glaspy JA, Seja E, Ontiveros M, Reardon DL, Renteria R, Englahner B, Economou JS, Gomez-Navarro J, Ribas A. Definition of an Immunologic Response Using the Major Histocompatibility Complex Tetramer and Enzyme-Linked Immunospot Assays. Clin Cancer Res 2006; 12:107-16. [PMID: 16397031 DOI: 10.1158/1078-0432.ccr-05-0136] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Define an immunologic response using the tetramer and enzyme-linked immunospot (ELISPOT) assays. EXPERIMENTAL DESIGN Ten healthy subjects and 21 patients with melanoma (all HLA-A*0201) donated a total of 121 blood samples to determine the lower limit of detection (LLD), analytic coefficient of variation (aCV), and physiologic CV (pCV) of the tetramer and ELISPOT assays. The mean, SD, and reference change value (RCV) were calculated to define changes beyond the assay imprecision, and its application was tested in the monitoring of T-cell expansion after CTLA4 blockade with ticilimumab (CP-675,206). RESULTS The LLD for the tetramer assay was 0.038% CD8+ cells and seven spots per 10(5) peripheral blood mononuclear cells for the ELISPOT assay. The aCV of the tetramer assay was <10% and was higher for the ELISPOT (24.69-36.32%). There was marked between-subject variability on baseline homeostatic values, which was correlated to prior antigen exposure. An immunologic response was defined as an increase beyond the mean + 3 SD in antigen-specific cells for subjects with baseline levels below the LLD, or beyond the assay RCV for baseline levels above the LLD. In four patients receiving ticilimumab, expansions of antigen-specific T cells beyond the assay variability were noted for EBV and MART1 antigens. CONCLUSIONS A combined approach of change from negative (below the LLD) to positive (above the LLD) and a percentage change beyond the assay variability using the RCV score can be computed to define which change in circulating antigen-specific T cells represents a response to immunotherapy.
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Affiliation(s)
- Begoña Comin-Anduix
- Department of Surgery, Division of Surgical, University of California at Los Angeles, Los Angeles, California, USA
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Trapé J, Pérez de Olaguer J, Buxó J, López L. Biological Variation of Tumor Markers and Its Application in the Detection of Disease Progression in Patients with Non-Small Cell Lung Cancer. Clin Chem 2005; 51:219-22. [PMID: 15613716 DOI: 10.1373/clinchem.2004.040659] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jaume Trapé
- Clinical Laboratory, Hospital Sant Joan de Déu, Althaia Xarxa Assistencial de Manresa, 08243 Barcelona, Spain.
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26
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Worsfold M, Powell DE, Jones TJW, Davie MWJ. Assessment of Urinary Bone Markers for Monitoring Treatment of Osteoporosis. Clin Chem 2004; 50:2263-70. [PMID: 15472034 DOI: 10.1373/clinchem.2004.037424] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: The usefulness of urinary markers of bone turnover in monitoring therapy depends on their within-person variability compared with their responses to therapy. The aim of this study was to assess the performance of two such markers on this basis.
Methods: We measured variation, during a whole year, of cross-linked N-terminal telopeptide of collagen I (NTx) and urinary deoxypyridinoline (DPD) as ratios to creatinine concentration and after log-transformation of the ratios in untreated women stratified into three bone density classes, of which the lowest was osteoporotic. We also measured changes in bone mineral density at the lumbar spine (LSBMD) and hip (FNBMD) in untreated women with normal bones and in those with moderate osteopenia and calculated the reference change value (RCV; or least significant change) at P <0.05 for all of these measures. We made the same measurements on women treated with bisphosphonates, estrogen replacement (HRT), or calcium and examined their individual responses to treatment compared with RCV.
Results: After 12 months on bisphosphonates, LSBMD changed more than RCV (2.55%) in 47% of women compared with 44% of those on HRT and 13% of those on calcium. Response of FNBMD was less. Log NTx (RCV= −28%) responded to bisphosphonates in 78%, regardless of BMD, but less often to HRT (67%). Log DPD (RCV= −30%) responded to bisphosphonates less frequently (31% at 12 months).
Conclusions: NTx has advantages over DPD in monitoring therapy for osteoporosis when mailed urine samples are used.
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Affiliation(s)
- Michael Worsfold
- Charles Salt Centre, Robert Jones and Agnes Hunt Orthopaedic and District Hospital, Oswestry, Shropshire, SY10 7AG, United Kingdom.
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27
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Abstract
AbstractThe concept of reference values is widely accepted, but their application has been quite lax over the years. This is due primarily to the difficulty of properly selecting and documenting samples from a reference population. In the absence of a clear description of reference individuals, reference values lose their meaning, are ambiguous at best, and are often confused with decision limits. The clinical medicine perspective of reference values is to rule out diseases and to define health, while that of preventive medicine is to appreciate the state of health. Defining reference limits and normality in this context is a great challenge. Advances in the fields of genomics and proteomics and the rapid pace of technological advances help highlight the biological diversity among individuals. However, there is a great need for reference values that are representative of healthy humans and presented in a manner that they can be utilized by all laboratories. In addition, as secure information technology becomes available, the goal of using an individual as their own reference during a lifetime is now possible, provided that consistency of databases is ensured.
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Affiliation(s)
- Claude Petitclerc
- Département de Biochimie, Centre Hospitalier de I'Université de Montréal, Hôpital Notre-Dame, Montréal, Canada.
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28
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Abstract
AbstractWhen a biological quantity examination exhibits a high degree of individuality, developing a strategy for interpreting these values in an individual context can be a useful alternative. Time-series analysis is the appropriate statistical framework to build a model for explanation of the behaviour of laboratory information and to forecast future values. The key concepts in this approach are autocorrelation and withinperson variance. Unfortunately, the powerful tools provided by time-series analysis require many observations, a requisite difficult to meet in every day practice. However, introducing some restrictions in the autocorrelation parameter of the most reliable model, the first order autocorrelation model, and using the average within-person variance from a selected population, it is possible to build predictive reference intervals for an individual, based on only few observations. The most common case is the minimum time series: when there are just two observations. The statistical significance of the change from a previous observation is a problem that arises from both quality control (delta checks) and the interpretative diagnostic fields (reference change limit). Applying the same restrictive criteria, it is possible to develop specific limits for a difference between consecutive observations based on a within-person variance selected from the distribution of variances found in a sample of similar individuals.
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Affiliation(s)
- Josep M Queraltó
- Servei de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
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29
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Trapé J, Botargues JM, Porta F, Ricós C, Badal JM, Salinas R, Sala M, Roca A. Reference change value for alpha-fetoprotein and its application in early detection of hepatocellular carcinoma in patients with hepatic disease. Clin Chem 2003; 49:1209-11. [PMID: 12816928 DOI: 10.1373/49.7.1209] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jaume Trapé
- Laboratori d'Analisis Clíniques, Secció de Gastroenterologia, Hospital Sant Joan de Déu, Althaia Xarxa Assistencial de Manresa, Dr. Joan Soler, s/n 08243 Manresa, Barcelona, Spain.
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30
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Trapé J, Aliart ML, Brunet M, Dern E, Abadal E, Queraltó JM. Reference change value for HbA1c in patients with type 2 diabetes mellitus. Clin Chem Lab Med 2000; 38:1283-7. [PMID: 11205694 DOI: 10.1515/cclm.2000.202] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We estimated reference change value and steady state disease biological variation of glycohemoglobin (HbA1c) from serial measurements in 47 clinically stable type 2 diabetes patients whose home-measured capillary glucose was stable throughout the study. Whole blood HbA1c assays were performed by turbidimetric inhibition immunoassay. The analytical imprecision (coefficient of variation) was 7.1% and 5.0% for control materials with HbA1c of 5.1% and 10.7%, respectively (n=152). The sampling interval was 6 months. Patients were classified into three groups (good, acceptable and poor control) according to the American Diabetes Association (ADA) clinical practice recommendations of 1999 based on HbA1c reference interval. Steady state disease biological variation for each control group was 7.9%, 5.4% and 3.9%. HbA1c absolute reference change value was 1.42, 1.50 and 1.37%, or as relative reference change value, 29.1%, 24.4% and 17.8%, respectively. The analytical goal, defined as one-half of the biological variation, was lower than 3.9% for well-controlled patients.
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Affiliation(s)
- J Trapé
- Servei de Laboratori, Hospital General de Manresa, Barcelona, Spain.
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31
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Alvarez L, RicOs C, Peris P, GuaNabens N, Monegal A, Pons F, Ballesta AM. Components of biological variation of biochemical markers of bone turnover in Paget's bone disease. Bone 2000; 26:571-6. [PMID: 10831927 DOI: 10.1016/s8756-3282(00)00279-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The aims of this study were to evaluate the components of biological variation of the new markers of bone turnover in patients with Paget's bone disease and to compare the results with data obtained in healthy subjects. Fifteen patients with Paget's disease in a stable period of the disease and 12 healthy premenopausal women were included for a 1 year follow-up study. Within- and between-subject biological variation, indices of individuality, and critical differences were evaluated for the following biochemical markers: in serum, total (tAP), and bone (bAP) alkaline phosphatases, procollagen type I N-terminal propeptide (PINP) and beta-carboxyterminal telopeptide of type I collagen (sCTx); in urine, hydroxyproline (Hyp), and amino (NTx) and beta-carboxyterminal (CTx) telopeptides of collagen type I. Serum markers of bone turnover showed lower biological variability than urinary markers. Within-subject biological variation was higher in pagetic patients than in healthy subjects for all serum markers. In both groups, bAP presented the lowest within-subject biological variation. In pagetic patients, all markers presented indices of individuality of <0.6, indicating their usefulness for patient monitoring. Critical differences were lower for serum markers than for urinary markers. Among pagetic patients, serum bAP and PINP showed the lowest critical differences with values close to 30%, whereas urinary CTx presented the highest critical differences (near 70%). Conversely, in healthy subjects, tAP was the marker with the lowest critical differences, being two-fold higher in pagetic patients. This study confirms the lower sensitivity of urinary markers to detect significant changes and indicates that data obtained on biological variations from healthy populations cannot always be extrapolated to pathological conditions. In addition, serum bAP and PINP seem to be the markers that best reflect a significant change in activity of Paget's disease.
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Affiliation(s)
- L Alvarez
- Clinical Biochemistry, Hospital Clinic, University of Barcelona, Barcelona, Spain.
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32
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Abstract
Within- and between-subject variability in serum and salivary lithium concentrations in nine psychiatric inpatients on stable drug regimens undergoing therapy has been assessed using criteria for determining biologic variation. This allows separation of analytic from other measures of variance. There were marked differences in inter- and intra-subject variance for serum and salivary lithium concentrations for serum/salivary ratios. Moreover, these variances were greater for salivary lithium than for serum concentrations. The results have been used to assess analytical performance, the usefulness of the therapeutic range, and the reference change interval. Despite greater variance for salivary concentrations, predicted serum concentrations from predetermined serum/saliva ratios were in good agreement with actual concentrations in most subjects.
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Affiliation(s)
- J P Moody
- Biochemical Medicine, Dundee Teaching Hospitals N.H.S. Trust, Ninewells Hospital and Medical School, Scotland
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33
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Kjeldsen J, Lauritsen K, De Muckadell OB. Serum concentrations of orosomucoid: improved decision-making for tapering prednisolone therapy in patients with active inflammatory bowel disease? Scand J Gastroenterol 1997; 32:933-41. [PMID: 9299674 DOI: 10.3109/00365529709011205] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The reliability of clinical judgment for the tapering of glucocorticoids in patients with active inflammatory bowel disease has been questioned. METHODS The current study compared decision-making strategies on the basis of a combination of disease indices and serum concentrations of orosomucoid (strategy A) and disease indices only (strategy B) for the tapering of prednisolone. Twenty-nine patients with clinically active ulcerative colitis and 59 patients with Crohn's disease and increased concentrations of S-orosomucoid participated. The initial dose of prednisolone was 40 or 75 mg, which was tapered off over a minimum of 6 or 8 weeks. RESULTS The tapering schedule was completed in 11 of 44 (25%) patients treated in accordance with strategy A, whereas 28 of 44 patients (64%) and prednisolone completely tapered, in accordance with strategy B. At follow-up 4 of 11 patients (36%) and 17 of 28 patients (61%) treated in accordance with strategies A and B, respectively, had clinical relapse (0.10 > P > 0.05). By means of multiple regression analysis a high serum concentration of orosomucoid and previous disease activity were identified as predictors of relapse. CONCLUSION A therapeutic end-point of normalization of an increased level of S-orosomucoid in addition to clinical remission may be difficult to use, as serum concentrations may be continuously increased in spite of clinical remission. However, this goal may still be relevant, as a trend towards higher risk of relapse was found in patients with increased orosomucoid concentrations after completing therapy.
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Affiliation(s)
- J Kjeldsen
- Dept. of Medical Gastroenterology, Odense University Hospital, Denmark
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34
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Mora J, Queraltó JM. Within-subject variation of carcinoembryonic antigen in colorectal cancer -- application of reference of change values and individual reference ranges to patient follow-up. EUROPEAN JOURNAL OF CLINICAL CHEMISTRY AND CLINICAL BIOCHEMISTRY : JOURNAL OF THE FORUM OF EUROPEAN CLINICAL CHEMISTRY SOCIETIES 1997; 35:453-7. [PMID: 9228329 DOI: 10.1515/cclm.1997.35.6.453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dynamic interpretation of results is an alternative approach to the conventional cut-off procedure. Reference change limit is a valuable reference point to interpret dynamically tumour marker values when only very few serial results can be obtained from a patient after treatment. In this paper, a reference change limit of 2.0 microg/l was estimated for carcinoembryonic antigen in patients with complete remission of colorectal cancer. This figure means that a difference greater than 2.0 microg/l has at least a chance of being statistically significant (at 0.05 probability). As complementary information to the reference change limits, with more than four successive results, a simple time series model can be used to obtain predictive limits for the next observation.
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Affiliation(s)
- J Mora
- Servei de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona,Spain
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35
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Taylor AJ, Vadgama P. Analytical reviews in clinical biochemistry: the estimation of urea. Ann Clin Biochem 1992; 29 ( Pt 3):245-64. [PMID: 1610100 DOI: 10.1177/000456329202900301] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- A J Taylor
- Department of Medicine (Clinical Biochemistry), Hope Hospital, Salford, UK
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36
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Huguet J, Fuentes-Arderiu X. Biological variation in the catalytic concentration of pancreatic alpha-amylase and triacylglycerol lipase in serum. Scand J Clin Lab Invest 1991; 51:735-8. [PMID: 1806988 DOI: 10.3109/00365519109104588] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The within-subject and between-subject biological variation in the catalytic concentration of pancreatic alpha-amylase and triacylglycerol lipase in serum have been studied. The study was performed during a 13-month period in a group of 42 supposedly healthy individuals, 19 women and 23 men. All measurements were carried out using a Hitachi 717 analyser at 37 degrees C. The medians of the within-subject biological coefficients of variation obtained for the catalytic concentration of pancreatic alpha-amylase and triacylglycerol lipase in serum were 8.1 and 38.9%, respectively. The index of individuality for the catalytic concentration of pancreatic alpha-amylase and triacylglycerol lipase in serum was 0.27 and 1.20, respectively. Consequently, it is not advisable to use population-based reference intervals for the catalytic concentration of pancreatic alpha-amylase and triacylglycerol lipase in serum.
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Affiliation(s)
- J Huguet
- Servei de Bioquímica Clínica, Hospital Prínceps d'Espanya, Barcelona, Spain
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37
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Mori H, Nakamura T, Nose Y. A method for early detection of abnormal trends in serial clinical examination results over time. MEDICAL INFORMATICS = MEDECINE ET INFORMATIQUE 1989; 14:297-308. [PMID: 2622294 DOI: 10.3109/14639238908999284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this paper we describe a method for the early detection of changing health conditions which may eventually lead to serious disease. The method makes use of health screening test results accumulated for individuals and can be applied to those who have taken at least four health examinations. The degree of abnormality is calculated using a logistic regression equation. The variables defining the equation are selected by factor analysis and a stepwise variable selection method based on the likelihood ratio criterion. Statistical estimates include linear regression coefficients, isotonic regression probabilities and their standard deviations. These are used to represent trends in health screening results over time. The method is illustrated using a sample of 308 persons with gastric cancer and 3002 healthy persons. Cross-validations were also performed.
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Affiliation(s)
- H Mori
- Scientific Data Center of A-Bomb Disasters, Nagasaki University School of Medicine, Japan
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38
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Fraser CG, Harris EK. Generation and application of data on biological variation in clinical chemistry. Crit Rev Clin Lab Sci 1989; 27:409-37. [PMID: 2679660 DOI: 10.3109/10408368909106595] [Citation(s) in RCA: 666] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Most clinical chemical analytes vary in a random manner around a homeostatic set point. Replicate analyses of a series of specimens collected from a group of subjects allows estimation of analytical, within and between subject components of variation. The preferred experimental procedures and statistical methods for evaluation of data and analysis of variance are described; a detailed example is provided in the Appendix. The many uses of data on biological variation in clinical chemistry are reviewed, including setting analytical goals, deciding the significance of changes in serial results from an individual, evaluating the utility of conventional population-based reference values in patient management, and other applications.
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Affiliation(s)
- C G Fraser
- Department of Biochemical Medicine, Ninewells Hospital and Medical School, Dundee, Scotland
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39
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van Geen F. Intra- and interindividual variability of biochemical and haematological parameters in periodical health surveillance. Int Arch Occup Environ Health 1988; Suppl:65-75. [PMID: 3170002 DOI: 10.1007/978-3-642-73476-2_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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40
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Godsland IF. Intra-individual variation: significant changes in parameters of lipid and carbohydrate metabolism in the individual and intra-individual variation in different test populations. Ann Clin Biochem 1985; 22 ( Pt 6):618-24. [PMID: 3907483 DOI: 10.1177/000456328502200612] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Fasting serum triglyceride, cholesterol, HDL cholesterol, HDL 2&3 cholesterol, fasting plasma glucose and insulin and haemoglobin A1 were measured under standardised conditions in a group of laboratory volunteers. Intra-individual variation was calculated for each parameter from weekly measurements on at least eleven successive occasions, and the minimum change in each parameter that would be significant at the level P less than 0.05 was calculated. A further study compared intra-individual variation in different test populations. Data from the group of laboratory volunteers were taken to represent intra-individual variation under standard test conditions with an informed test population and data from a group of regularly monitored out-patients undergoing drug therapy for hypercholesterolaemia were taken to represent intra-individual variation under standard conditions in a typical test population. A group of in-patients under strict dietary control provided information on variation under extreme standardisation of test conditions. Intra-individual variation was greatest for all parameters in the outpatient population. Extreme standardisation of test condition reduced intra-individual variation beyond that of the laboratory volunteers only in the case of serum triglyceride.
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41
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Connelly DP. Short-Term Serial Testing: Functions and Analytic Methods. Clin Lab Med 1982. [DOI: 10.1016/s0272-2712(18)31016-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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42
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Hyltoft Petersen P, Feldt-Rasmussen U, Hørder M, Blaabjerg O, Thygesen K. Variability of plasma proteins according to molecular size. Long-term and short-term intra-individual variation. Scand J Clin Lab Invest 1981; 41:143-50. [PMID: 6171859 DOI: 10.3109/00365518109092026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The intra-individual variations in serum concentrations of alpha 1-antitrypsin, albumin and alpha 2-macroglobulin were determined using high precision analytical methods. The long-term (3 months) variations were 8.2% for alpha 1-antitrypsin and 2.9% for alpha 2-macroglobulin in five males and five females. The coefficients of variation for albumin were 1.5 and 3.4% for males and females, respectively. In males the long-term variations of albumin and alpha 2-macroglobulin were highly correlated. The short-term (2 days) intra-individual variations in six males were 2.5, 3.8 and 3.4% for alpha 1-antitrypsin, albumin and alpha 2-macroglobulin respectively (coefficients of variation). A diurnal variation was found for albumin with maximal concentrations at 18.00 hours. At 6.00 and 10.00 hours the fractional concentrations of alpha 1-antitrypsin and albumin were lower than for alpha 2-macroglobulin. The variations of the three proteins were positively correlated.
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