References of "Clinica Chimica Acta"
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See detailVascular calcification: from pathophysiology to biomarkers
EVRARD, Séverine ULg; DELANAYE, Pierre ULg; Kamel, S et al

in Clinica Chimica Acta (in press)

The link between vascular calcification (VC) and increased mortality is now well established. Over time, as clinical importance of this phenomenon has begun to be fully considered, scientists have ... [more ▼]

The link between vascular calcification (VC) and increased mortality is now well established. Over time, as clinical importance of this phenomenon has begun to be fully considered, scientists have highlightedmore and more physiopathological mechanisms and signaling pathways that underlie VC. Several conditions such as diabetes, dyslipidemia and renal diseases are undoubtedly identified as predisposing factors. But even if the process is better understood,many questions still remain unanswered. This reviewbriefly develops the various theories that attempt to explain mineralization genesis. Nonetheless, the main purpose of the article is to provide a profile of the various existing biomarkers of VC. Indeed, in the past years, a lot of inhibitors and promoters, which form a dense and interconnected network, were identified. Given importance to assess and control mineralization process, a focusing on accumulated knowledge of each marker seemed to be necessary. Therefore, we tried to define their respective role in the physiopathology and how they can contribute to calcification risk assessment. Among these, Klotho/fibroblast growth factor-23, fetuin-A, Matrix Gla protein, Bone morphogenetic protein-2, osteoprotegerin, osteopontin, osteonectin, osteocalcin, pyrophosphate and sclerostin are specifically discussed. [less ▲]

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See detailEnzymatic creatinine assays allowestimation of glomerular filtration rate in stages 1 and 2 chronic kidney disease using CKD-EPI equation
Kuster, Nils; Cristol, Jean-Paul; CAVALIER, Etienne ULg et al

in Clinica Chimica Acta (2014), 428

The National Kidney Disease Education Program group demonstrated that MDRD equation is sensitive to creatinine measurement error, particularly at higher glomerular filtration rates. Thus, MDRD-based eGFR ... [more ▼]

The National Kidney Disease Education Program group demonstrated that MDRD equation is sensitive to creatinine measurement error, particularly at higher glomerular filtration rates. Thus, MDRD-based eGFR above 60 mL/min/1.73 m2 should not be reported numerically. However, little is known about the impact of analytical error on CKD-EPI-based estimates. This study aimed at assessing the impact of analytical characteristics (bias and imprecision) of 12 enzymatic and 4 compensated Jaffe previously characterized creatinine assays on MDRD and CKD-EPI eGFR. In a simulation study, the impact of analytical error was assessed on a hospital population of 24 084 patients. Ability using each assay to correctly classify patients according to chronic kidney disease (CKD) stages was evaluated. For eGFR between 60 and 90 mL/min/1.73 m2, both equations were sensitive to analytical error. Compensated Jaffe assays displayed high bias in this range and led to poorer sensitivity/specificity for classification according to CKD stages than enzymatic assays. As compared to MDRD equation, CKD-EPI equation decreases impact of analytical error in creatinine measurement above 90 mL/min/1.73 m2. Compensated Jaffe creatinine assays lead to important errors in eGFR and should be avoided. Accurate enzymatic assays allow estimation of eGFR until 90 mL/min/1.73 m2 with MDRD and 120 mL/min/1.73 m2 with CKD-EPI equation. [less ▲]

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See detailEnzymatic but not compensated Jaffe methods reach the desirable specifications of NKDEP at normal levels of creatinine. results of the French multicentric evaluation
Boutten, Anne; Bargnoux, Anne-Sophie; Carlier, Marie-Christine et al

in Clinica Chimica Acta (2013), 419

The French Society of Clinical Biochemistry conducted this study to compare the accuracy and performances of the best creatinine enzymatic assays and the compensated Jaffe methods from the same ... [more ▼]

The French Society of Clinical Biochemistry conducted this study to compare the accuracy and performances of the best creatinine enzymatic assays and the compensated Jaffe methods from the same manufacturers. Creatinine was measured in 3 serum pools with creatinine levels of 35.9±0.9 μmol/L, 74.4±1.4 μmol/L, and 97.9±1.7 μmol/L (IDMS determination). The performances of the assays (total error that includes the contribution of bias and imprecision) were evaluated using Monte-Carlo simulations and compared against desirable NKDEP criteria. The enzymatic assays always fell within the desirable total Error of 7.6%. By contrast, this requirement was never obtained for the compensated Jaffe methods at the critical level of 74.4±1.4 μmol/L. Only the compensated Jaffe creatinine on Olympus analyzer reached this specification at 35.9±0.9 and 97.9±1.7 μmol/L levels. This study demonstrates that, despite substantial improvement regarding traceability to the IDMS reference method and precision, compensated Jaffe creatinine methods, by contrast to enzymatic ones, do not reach the desirable specifications of NKDEP at normal levels of creatinine. [less ▲]

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See detailParathormone and bone-specific alkaline phosphatase for the follow-up of bone turnover in hemodialysis patients : Is it so simple?
DELANAYE, Pierre ULg; DUBOIS, Bernard ULg; JOURET, François ULg et al

in Clinica Chimica Acta (2013), 417

Background: Chronic Kidney Disease (CKD) is associated with mineral and bone disorders (MBD). International guidelines suggest that levels of serum parathormone (PTH) or bone-specific alkaline phosphatase ... [more ▼]

Background: Chronic Kidney Disease (CKD) is associated with mineral and bone disorders (MBD). International guidelines suggest that levels of serum parathormone (PTH) or bone-specific alkaline phosphatase (b-ALP) can be used to evaluate MBD in dialysis patients. The evidence remains moderate and based on transversal studies. <br />Methods: We retrospectively investigated the variations of PTH (ΔPTH) and b-ALP (Δb-ALP) serum concentrations over a short (6-weeks) and a long (one-year) period in a monocentric hemodialysis population. The proportion of patients reaching the critical difference (CD) (50% for PTH and 25% for b-ALP) was calculated. <br />Results: Seventy-seven patientswere included. A significant correlation between PTHand b-ALP levelswas found at baseline (r=0.51). By contrast, no correlation was observed between ΔPTH and Δb-ALP over a 6-week interval (r=0.07). The CD for PTH and b-ALP was reached by 19 and 11 patients, respectively, with 2 patients showing consistent variations of both biomarkers. One year later, measurements were repeated in 48 survivors. <br />No correlation was found between ΔPTH and Δb-ALP (r=0.27). The CD for PTH or b-ALP was reached by 24 patients and 28 patients, respectively, with 6 patients (12.5%) showing opposite results for both biomarkers. <br />Conclusion: This study shows the lack of correlation between ΔPTH and Δb-ALP over time in patients under chronic hemodialysis. [less ▲]

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See detailEnzymatic but not compensated Jaffe methods reach the desirable specifications of NKDEP at normal levels of creatinine. Results of the French multicentric evaluation
Boutten, A; Bargnoux, A.S.; Carlier, M.C. et al

in Clinica Chimica Acta (2013), 419

The French Society of Clinical Biochemistry conducted this study to compare the accuracy and performances of the best creatinine enzymatic assays and the compensated Jaffe methods from the same ... [more ▼]

The French Society of Clinical Biochemistry conducted this study to compare the accuracy and performances of the best creatinine enzymatic assays and the compensated Jaffe methods from the same manufacturers. Creatinine was measured in 3 serum pools with creatinine levels of 35.9 ± 0.9 μmol/L, 74.4 ± 1.4 μmol/L, and 97.9 ± 1.7 μmol/L (IDMS determination). The performances of the assays (total error that includes the contribution of bias and imprecision) were evaluated using Monte-Carlo simulations and compared against desirable NKDEP criteria. The enzymatic assays always fell within the desirable total Error of 7.6%. By contrast, this requirement was never obtained for the compensated Jaffe methods at the critical level of 74.4 ± 1.4 μmol/L. Only the compensated Jaffe creatinine on Olympus analyzer reached this specification at 35.9 ± 0.9 and 97.9 ± 1.7 μmol/L levels. This study demonstrates that, despite substantial improvement regarding traceability to the IDMS reference method and precision, compensated Jaffe creatinine methods, by contrast to enzymatic ones, do not reach the desirable specifications of NKDEP at normal levels of creatinine. [less ▲]

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See detailDemystifying ethnic/sex differences in kidney function: is the difference in (estimating) glomerular filtration rate or in serum creatinine concentration?
Pottel, Hans; Hoste, Liesbeth; DELANAYE, Pierre ULg et al

in Clinica Chimica Acta (2012), 413(19-20), 1612-17

BACKGROUND: The recent evaluation of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for estimating the glomerular filtration rate (GFR) in multiple ethnicities has raised the ... [more ▼]

BACKGROUND: The recent evaluation of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for estimating the glomerular filtration rate (GFR) in multiple ethnicities has raised the question on how well this equation performs for African-American and Asian subjects. There is no doubt that serum creatinine (Scr) concentration differs between ethnicities and sexes. We show that creatinine-based equations for white populations may be inaccurate for estimating GFR in other ethnic/gender groups, especially in populations from Asia. METHODS: This study presents a mathematical analysis of the CKD-EPI-equation complemented with a literature review of median and reference values for IDMS-standardized Scr-concentrations for multiple ethnicities. RESULTS: The study shows that at equal eGFR-CKD-EPI-values, the ratio of Scr between females and males equals 0.79 and between other ethnicities/sexes and white males is constant too. From this information, it is possible to calculate mean Scr-values that correspond very well with literature values directly obtained from Scr-distributions in healthy white males and females and in black males, but the discrepancy is larger for other populations. CONCLUSIONS: Our results confirm the criticism that has been raised for using the CKD-EPI-equation for these ethnicities. An alternative eGFR-model is proposed based on a population-normalized Scr that needs further validation. [less ▲]

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See detailComparison of acid and enzymatic methods for insulin dosage: Analytical performances and impact on glomerular filtration rate evaluation
DELANAYE, Pierre ULg; Thibaudin, L.; Souvignet, M. et al

in Clinica Chimica Acta (2012), 413(5-6), 556-560

Among issues susceptible to hamper a reliable measurement of inulin clearance, those regarding the dosage of inulin are largely neglected. We have compared the analytical performances of 2 commonly used ... [more ▼]

Among issues susceptible to hamper a reliable measurement of inulin clearance, those regarding the dosage of inulin are largely neglected. We have compared the analytical performances of 2 commonly used methods of inulin dosage (one “acid” and one “enzymatic” method) and studied their potential impact on the glomerular filtration rate (GFR) value given by inulin clearance. Repeatability, uncertainty and the beta-expectation limits were evaluated from pre-determined serum and urine pools of inulin. Agreement between the two methods was analyzed from 99 inulin clearances performed in renal transplant patients. Impact of the method of dosage on GFR evaluation was simulated according to the respective beta-expectations limits of each method. Overall, intra-assay coefficient of variability and relative bias were inferior to 5% and 10% for both methods. Contrary to the acid method, analytical performance of the enzymatic method was not influenced by the presence of glucose. The relative difference in GFR values obtained with the two methods in transplant patients was − 0.4 ± 10%. Simulations suggested that changes in inulin concentration attributable to analytical error could modify the value of GFR from − 12% to + 28%. In conclusion, while analytical performances are globally acceptable for both methods, they are not strictly equivalent. The impact on the determination of GFR, albeit limited, is not negligible and adds to other sources of inaccuracy. International standardization for the dosage of inulin is necessary. [less ▲]

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See detailComparison of different approaches to evaluate External Quality Assessment Data.
Coucke, Wim; China, Bernard; Delattre, Isabelle et al

in Clinica Chimica Acta (2012), 413(5-6), 582-6

In EQA programs, Z-scores are used to evaluate laboratory performance. They should indicate poorly performing laboratories, regardless of the presence of outliers. For this, two different types of ... [more ▼]

In EQA programs, Z-scores are used to evaluate laboratory performance. They should indicate poorly performing laboratories, regardless of the presence of outliers. For this, two different types of approaches exist. The first type are "outlier-based" approaches, which first exclude outlying values, calculate the average and standard deviation on the remaining data and obtain Z-scores for all values (e.g., Grubbs and Dixon). The second type includes the "robust" approaches (e.g., Tukey and Qn or the algorithm recommended by ISO). The different approaches were assessed by randomly generated samples from the Normal and Student t distributions. Part of the sample data were contaminated with outliers. The number of false and true outliers was recorded and subsequently, Positive and Negative Predictive Values were derived. Also, the sampling mean and variability were calculated for location and scale estimators. The various approaches performed similarly for sample sizes above 10 and when outliers were at good distance from the centre. For smaller sample sizes and closer outliers, however, the approaches performed quite differently. Tukey's method was characterised by a high true and a high false outlier rate, while the ISO and Qn approaches demonstrated weak performance. Grubbs test yielded overall the best results. [less ▲]

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See detailHuman anti-animal antibodies interference in the Siemens Immulite chemiluminescent insulin immuno-assay: about one case
Cavalier, Etienne ULg; Huberty, Véronique; Carlisi, Ignazia ULg et al

in Clinica Chimica Acta (2011), 412(7-8), 668-669

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See detail3-years experience review of neonatal screening for hemoglobin disorders using tandem mass spectrometry.
BOEMER, François ULg; Cornet, Yves ULg; LIBIOULLE, Cécile ULg et al

in Clinica Chimica Acta (2011), 412(15-16), 1476-9

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main technique used for hemoglobin variant detection. METHODS: Since tandem mass spectrometry is being used for screening of inherited metabolic disorders and allows protein identification, we had developed an application to identify the most relevant hemoglobin mutations with this technology. RESULTS: This approach had been previously validated and has been routinely applied in our laboratory for the last three years. We report here our experience with this new method in the field, applied to our East-Belgian population. CONCLUSIONS: To conclude, mass spectrometry provides an efficient alternative approach for laboratories performing neonatal screening of hemoglobin disorders. [less ▲]

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See detailUrinary NGAL measurement : Biological variation and ratio to creatinine
Delanaye, Pierre ULg; Rozet, Eric ULg; Krzesinski, Jean-Marie ULg et al

in Clinica Chimica Acta (2011), 412(3-4), 390

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See detailA multicentric evaluation of IDMS-traceable creatinine enzymatic assays
Pieroni, Laurence; DELANAYE, Pierre ULg; Boutten, Anne et al

in Clinica Chimica Acta (2011), 412

Chronic kidney disease definition is based on glomerular filtration rate (GFR) estimations which are derived from creatinine-based equations. The accuracy of GFR estimation is thus largely dependent of ... [more ▼]

Chronic kidney disease definition is based on glomerular filtration rate (GFR) estimations which are derived from creatinine-based equations. The accuracy of GFR estimation is thus largely dependent of those of serum creatinine assays. International recommendations highlight the need for traceable creatinine assays. The French Society of Clinical Biochemistry conducted a study for measuring accuracy of creatinine enzymatic methods. This evaluation involved 25 clinical laboratories. Creatinine was measured in serum pools ranging from 35.9±0.9 μmol/L to 174.5±3.1 μmol/L (IDMS determination) using 12 creatinine enzymatic methods. For all creatinine values greater than 74.4±1.4 μmol/L, the bias and imprecision did not exceed 5% and 5.9%, respectively. For the lowest value (35.9±0.9 μmol/L), the bias ranged from −1.8 to 9.9% (with one exception). At this level, the imprecision ranged from 1.9 to 7.8%. The true performances of the assays (couples of bias and relative standard deviation), were evaluated using Monte-Carlo simulations. Most of the assays fall within the maximum Total Error of 12% at all concentrations. This study demonstrates substantial improvements in the calibration, traceability and precision of the enzymatic methods, reaching the NKDEP recommendations. Moreover, most of these assays allowed accurate creatinine measurements for creatinine levels lower than 40 μmol/L. [less ▲]

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See detailFalse positive PTH results: An easy strategy to test and detect analytical interferences in routine practice
Cavalier, Etienne ULg; Carlisi, Agnès; Chapelle, Jean-Paul ULg et al

in Clinica Chimica Acta (2008), 387(1-2), 150-152

Background: As other immunoassays, PTH determination is not free from interferences. Indeed, natural antibodies like heterophile antibodies (HAMA) and rheumatoid factor (RF) can induce falsely elevated ... [more ▼]

Background: As other immunoassays, PTH determination is not free from interferences. Indeed, natural antibodies like heterophile antibodies (HAMA) and rheumatoid factor (RF) can induce falsely elevated results, leading to misdiagnosis and expensive unnecessary explorations. However, in routine practice, these interferences are not always obvious to detect. Methods: On 2084 PTH samples, we applied a validation strategy in four steps to screen for HAMA and rheumatoid factor interferences. Results: 36% of our samples presented an elevated PTH. We found a clinically plausible reason for 91% of them. The remaining 63 suspicious samples were treated with HBT and 40% of them were found to be HAMA positive. RF determination was performed on the HAMA-negative samples and RE was positive in 21 of them. They were then treated with RF-Absorbent. Nine of these 21 samples presented RE interference. Conclusion: Applying this strategy in our routine validation, we managed to avoid spuriously elevated PTH results, which could have caused medical errors as well as unnecessary cost-effective extra-investigations. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailAnalytical study of three cystatin C assays and their impact on cystatin C-based GFR-prediction equations.
Delanaye, Pierre ULg; Pieroni, Laurence; Abshoff, Christelle et al

in Clinica Chimica Acta (2008), 398(1-2), 118-24

BACKGROUND: Cystatin C-based equations are used to estimate GFR. However, three cystatin C immunoassays are on the market. Difference in cystatin C assays could have strong consequences on the accuracy ... [more ▼]

BACKGROUND: Cystatin C-based equations are used to estimate GFR. However, three cystatin C immunoassays are on the market. Difference in cystatin C assays could have strong consequences on the accuracy and precision of cystatin C-based equations. We have performed an analytical study of these three assays and studied potential differences between assays on the precision of cystatin C-based equations. METHODS: We have studied imprecision, recovery, linearity and interferences of the three immunoassays (nephelometric assay from Siemens and turbidimetric assays from Dako and Gentian). The impact of differences in cystatin C assays has been studied for the equations published by Levey (Siemens assay) and Grubb (Dako assay). RESULTS: Analytical performance of the Dako assay is slightly less high. For cystatin C values below 2.5 mg/L, no statistical difference is found between results given by the Dako and the Gentian assays. So, both assays can be used in the Grubb equation. Cystatin C results are different with the Siemens assay. The Levey equation, built with the Siemens assay, can only be used with cystatin C values measured with this assay. Using the Dako or Gentian assay results in the Levey equation can lead to differences in estimating GFR up to 6 mL/min/1.73 m2. Differences can reach 9.5 mL/min/1.73 m2 if the Siemens assay is used in the Grubb equation. CONCLUSION: The Siemens and Gentian assays seem analytically more valid than the Dako assay for cystatin C determination. Differences in cystatin C assays can lead to significant differences in cystatin C-based equations. However, these differences seem less important than the differences observed with creatinine and creatinine-based equations. [less ▲]

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