scholarly journals Verification study of free light chains assays on reagent-optimized analysers

2019 ◽  
Vol 29 (3) ◽  
pp. 579-586
Author(s):  
Dragana Šegulja ◽  
Danica Matišić ◽  
Karmela Barišić ◽  
Dunja Rogić
Keyword(s):  
Method Comparison ◽  
Correlation Coefficients ◽  
Light Chains ◽  
Free Light Chains ◽  
Serum Samples ◽  
Three Samples ◽  
Coefficients Of Variation ◽  
Satisfactory Precision ◽  
Haematological Patients ◽  
Method Comparison Study

Introduction: Our aim was to compare analytical specifications of two assays (monoclonal vs. polyclonal) for free light chains (FLCs) quantification optimized for two different analytical platforms, nephelometer ProSpec (Siemens, Erlangen, Germany) and turbidimetric analyser Optilite (The Binding Site, Birmingham, UK). Materials and methods: The evaluation included verification of the precision, repeatability and reproducibility, estimation of accuracy and method comparison study with 37 serum samples of haematological patients. Kappa and lambda FLC were measured in each sample by both methods and kappa/lambda ratio was calculated. Results: Results show satisfactory precision of both methods with coefficients of variation for ProSpec of CVwr = 2.20% and CVbr = 3.44%, and for Optilite CVwr = 2.82% and CVbr = 4.15%. Estimated bias for FLC lambda was higher on the ProSpec analyser, but bias for FLC kappa was higher on the Optilite analyser. Correlation coefficients were 0.98; P < 0.001 for FLC kappa and 0.97; P < 0.001 for FLC lambda. Considering normal/pathological FLC ratio moderate agreement within assays was detected (κ = 0.621). When the results were categorized according to criteria for progressive disease, 4/37 (0.10) cases were differently classified. Lambda FLC values by Optilite in three samples with monoclonal FLC lambda were more than twelve times higher than by ProSpec. A 25% difference in FLC ratio was detected in 16/37 (0.43) and 50% difference in 13/37 (0.35) patients. Conclusions: All manufacturers’ precision claims could not be achieved in the verification study. The comparison of results to biological variations data showed that coefficients of variations are acceptable for both assays. The assays should not be used interchangeably in haematological patients.

Comparison of Two Different Ultrasound Systems for the Evaluation of Tissue Doppler Velocities in Fetuses

2015 ◽  
Vol 40 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Mónica Cruz-Lemini ◽  
Brenda Valenzuela-Alcaraz ◽  
Francesc Figueras ◽  
Marta Sitges ◽  
Olga Gómez ◽  
...  
Keyword(s):  
Intraclass Correlation ◽  
Method Comparison ◽  
Correlation Coefficients ◽  
Tissue Doppler ◽  
Doppler Imaging ◽  
Specific Reference ◽  
Medical Systems ◽  
Intraclass Correlation Coefficients ◽  
Basal Septum ◽  
Method Comparison Study

Introduction: Recent studies have reported variations of up to 30% between different ultrasound machines for tissue Doppler imaging (TDI), a problem that can significantly impact clinical diagnosis, patient management and research studies. The objective of this study was to assess repeatability and agreement between fetal myocardial peak velocities evaluated by TDI with two different ultrasound systems. Materials and Methods: Systolic (S'), early (E') and late (A') diastolic myocardial peak velocities at mitral and tricuspid annuli as well as at the basal septum were evaluated by spectral TDI in 150 fetuses using two different ultrasound systems: Siemens Antares (Siemens Medical Systems, Malvern, Pa., USA) and Vivid Q (General Electric Healthcare, Horten, Norway). A method comparison study was performed, calculating intraclass correlation coefficients (ICC), and agreement was assessed by Bland-Altman plots. Results: Annular peak velocities showed lower values when measured by Vivid Q compared to values measured by Siemens Antares. ICC ranged from 0.07 (septal S') to 0.33 (right A'), showing very poor repeatability for clinical application. Agreement between the two systems was also poor, with high coefficients of variation for all measurements. Conclusions: Fetal annular peak velocities obtained with different ultrasound systems are not directly comparable. This is consistent with previous data in adults and warrants the need of system-specific reference values, suggesting that the same ultrasound machine should be used for longitudinal follow-up.

scholarly journals Harmonization of Serum Thyroid-Stimulating Hormone Measurements Paves the Way for the Adoption of a More Uniform Reference Interval

2017 ◽  
Vol 63 (7) ◽  
pp. 1248-1260 ◽  
Author(s):  
Linda M Thienpont ◽  
Katleen Van Uytfanghe ◽  
Linde A C De Grande ◽  
Dries Reynders ◽  
Barnali Das ◽  
...  
Keyword(s):  
Total Error ◽  
Method Comparison ◽  
Reference Interval ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Function Tests ◽  
Nonparametric Bootstrap ◽  
Serum Samples ◽  
Global Harmonization ◽  
Method Comparison Study ◽  
Stimulating Hormone

Abstract BACKGROUND The IFCC Committee for Standardization of Thyroid Function Tests developed a global harmonization approach for thyroid-stimulating hormone measurements. It is based on a multiassay method comparison study with clinical serum samples and target setting with a robust factor analysis method. Here we describe the Phase IV method comparison and reference interval (RI) studies conducted with the objective to recalibrate the participating assays and demonstrate the proof-of-concept. METHODS Fourteen manufacturers measured the harmonization and RI panel; 4 of them quantified the harmonization and first follow-up panel in parallel. All recalibrated their assays to the statistically inferred targets. For validation, we used desirable specifications from the biological variation for the bias and total error (TE). The RI measurements were done with the assays' current calibrators, but data were also reported after transformation to the new calibration status. We estimated the pre- and postrecalibration RIs with a nonparametric bootstrap procedure. RESULTS After recalibration, 14 of 15 assays met the bias specification with 95% confidence; 8 assays complied with the TE specification. The CV of the assay means for the harmonization panel was reduced from 9.5% to 4.2%. The RI study showed improved uniformity after recalibration: the ranges (i.e., maximum differences) exhibited by the assay-specific 2.5th, 50th, and 97.5th percentile estimates were reduced from 0.27, 0.89, and 2.13 mIU/L to 0.12, 0.29, and 0.77 mIU/L. CONCLUSIONS We showed that harmonization increased the agreement of results from the participating immunoassays, and may allow them to adopt a more uniform RI in the future.

scholarly journals A Comparative Study of Free Thyroxine Estimations

1982 ◽  
Vol 19 (2) ◽  
pp. 108-113 ◽  
Author(s):  
H A Ross ◽  
J W E Visser ◽  
P J Der Kinderen ◽  
J F W Tertoolen ◽  
J H H Thijssen
Keyword(s):  
Comparative Study ◽  
Correlation Coefficients ◽  
Reference Method ◽  
Measurement Range ◽  
Free Thyroxine ◽  
Methodological Error ◽  
Coefficients Of Variation ◽  
Satisfactory Precision ◽  
Dialysis Method

Two commercial methods (Immophase, Corning and FT4, Lepetit) for the measurement of free thyroxine (FT4) in serum have been experimentally evaluated. Ease of handling and rapidity were satisfactory. Precision profiles showed intra-assay coefficients of variation not exceeding 5% over the entire measurement range (0–70 pmol/l) for both methods. Interassay coefficients of variation were below 8%. Assay results of both methods correlated well with those obtained with a symmetric dialysis method, with correlation coefficients of 0·95 for the Immophase and 0·93 for the Lepetit method and slopes not significantly different from unity. Comparison with this reference method did not give any indication of serious methodological error in either of the kits in spite of theoretical doubts with regard to one of them.

scholarly journals Method comparison of three serum free light chain assays on the Roche Cobas 6000 c501 chemistry analyzer

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Dieuwertje Augustijn ◽  
Joannes F. M. Jacobs ◽  
Henk Russcher
Keyword(s):  
Method Comparison ◽  
Therapy Response ◽  
Reference Intervals ◽  
Light Chains ◽  
Reference Ranges ◽  
Free Light Chains ◽  
Monoclonal Gammopathies ◽  
Serum Free Light Chain ◽  
Roche Diagnostics ◽  
Roche Cobas

Abstract Objectives Free light chains (FLC) are important in the diagnosis, prognosis and monitoring of therapy response of patients with monoclonal gammopathies. In this study, we performed a method comparison of three FLC assays on the Cobas 6000 c501 chemistry analyzer of Roche Diagnostics. Methods Samples of 119 patients with various monoclonal gammopathies and 26 control patients were measured with the Freelite (The Binding Site), Diazyme (Diazyme Laboratories) and KLoneus (Trimero Diagnostics) FLC assays. A method comparison was performed and reference intervals of the three assays were validated. Results The analysis of the Bland-Altman agreement showed bias between the three FLC assays, ranging from −62.7 to 5.1% for κFLC and between −29.2 to 80.5% for λFLC. The Freelite and Diazyme assays have the highest agreement. The concordance of the FLC-ratio ranges from 41 to 75%, with the highest concordance between the Freelite and KLoneus assays. The FLC-ratio in 25 sera from healthy controls were within the reference ranges of the Freelite and KLoneus assays. The FLC-ratio was elevated in all 25 samples tested with the Diazyme assay. Conclusions The agreement for the free light chains is highest between the Freelite and the Diazyme assay and fair for the KLoneus assay. However, concordance of the FLC-ratio is highest when the Freelite and KLoneus assays were compared. Our data suggest that concordance for the Diazyme assay could be improved by recalibration. Because of absolute differences between the three methods in individual patients, none of the three FLC assays can be used interchangeably.

scholarly journals Endogenous Markers for Estimation of Renal Function in Peritoneal Dialysis Patients

2013 ◽  
Vol 33 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Krista Dybtved Kjaergaard ◽  
Jens Dam Jensen ◽  
Michael Rehling ◽  
Bente Jespersen
Keyword(s):  
Peritoneal Dialysis ◽  
Plasma Clearance ◽  
Method Comparison ◽  
Stable Condition ◽  
University Hospital ◽  
Coefficients Of Variation ◽  
Urine Production ◽  
Reproducible Method ◽  
Method Comparison Study ◽  
Development And Validation

ObjectiveThis method comparison study, conducted at the peritoneal dialysis (PD) outpatient clinic of the Department of Renal Medicine, Aarhus University Hospital, Denmark, set out to evaluate the accuracy and reproducibility of methods for estimating glomerular filtration rate (GFR) based on endogenous markers in PD patients.PatientsThe 12 consecutive patients included in the study were examined twice while in a stable condition. All patients finished the study. Inclusion criteria were age 18 years or older, ability to collect 24-hour urine, and urine production greater than 300 mL in 24 hours.Main Outcome MeasuresThe methods for estimating GFR using endogenous markers included the average of urinary clearances of creatinine and urea [U-Cl(crea–urea)] and two equations using the serum concentration of cystatin C [eGFR(CysC)]. The resulting GFR estimates were compared with those obtained using urinary and corrected plasma clearances of51Cr-EDTA [U-Cl(EDTA) and cP-Cl(EDTA)], the corrected plasma clearance being plasma clearance minus dialysate clearance.ResultsCompared with the U-Cl(EDTA), the U-Cl(crea–urea) GFR estimate was 12% higher [95% confidence limits (CL): 3%, 21%]. Although significantly different ( p = 0.01), the latter two methods showed the best agreement. The estimates obtained using the eGFR(CysC) methods were skewed from y = x compared with the estimates obtained using other methods, indicating strong bias, probably because of extrarenal elimination. The cP-Cl(EDTA) estimate was 34% (95% CL: 26%, 42%), higher than the U-Cl(EDTA) estimate ( p < 0.001). The reproducibility (coefficients of variation) differed significantly between methods: cP-Cl(EDTA), 7%; U-Cl(EDTA), 14%; U-Cl(crea–urea), 18%; and both eGFR(CysC) methods, 3%.ConclusionsIn PD patients, GFR may be estimated as U-Cl(crea–urea) when complete urine collection is performed, taking into account an overestimation of approximately 12%. The available equations for eGFR(CysC) seem to be inaccurate; further development and validation is desirable. Omitting the eGFR(CysC) methods, cP-Cl(EDTA) was the most reproducible method and might be useful in certain situations.

scholarly journals Clinical Comparisons of Two Free Light Chain Assays to Immunofixation Electrophoresis for Detecting Monoclonal Gammopathy

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Han-Sung Kim ◽  
Hyun Soo Kim ◽  
Kyu-Sung Shin ◽  
Wonkeun Song ◽  
Hyo Jung Kim ◽  
...  
Keyword(s):  
Light Chain ◽  
Monoclonal Gammopathy ◽  
Clinical Utility ◽  
Correlation Coefficients ◽  
Light Chains ◽  
Clinical Settings ◽  
Free Light Chains ◽  
Clinical Sensitivity ◽  
Immunofixation Electrophoresis ◽  
Plasma Cell Dyscrasias

Free light chains (FLCs) are useful biomarkers for the diagnosis and monitoring of various plasma cell dyscrasias. One hundred fifty-seven samples from 120 patients for screening or monitoring of monoclonal gammopathy (MG) were included. The new N Latex FLC assays (Siemens Healthcare Diagnostics GmbH, Germany) were compared with the Freelite FLC assays (The Binding Site Ltd., UK) and the results were analyzed with those of immunofixation electrophoresis (IFE). The Freelite FLC assay showed significantly wider assay ranges than the N Latex FLC assay. The correlation coefficients of the two FLC kappa (κ) assays, lambda (λ) assays, and theκ/λratio were 0.9792, 0.8264, and 0.9064, respectively. The concordance rate was 84.7% for the FLCκassays, 79.6% for FLCλ, and 89.2% for theκ/λratio. The clinical sensitivity and specificity of theκ/λratios were 72.2% and 93.6% for the Freelite assay and 64.6% and 100% for the N Latex FLC assay. Two FLC assays showed good correlations and concordance. However, the clinical sensitivity of theκ/λratio was higher in the Freelite FLC assays; clinical specificity was higher in the N Latex FLC assay. Both FLC assays seem to have limited clinical utility in detecting MG in certain clinical settings.

Free light chains and heavy/light chains in monitoring POEMS patients

2016 ◽  
Vol 54 (6) ◽  
Author(s):  
Sara Altinier ◽  
Kozeta Proko ◽  
Martina Zaninotto ◽  
Daniela Ciubotaru ◽  
Mara Seguso ◽  
...  
Keyword(s):  
Poems Syndrome ◽  
Light Chains ◽  
Vascular Endothelial ◽  
Free Light Chains ◽  
Serum Samples ◽  
Period Range ◽  
Endothelial Growth Factor ◽  
The Relationship

AbstractPOEMS syndrome is defined by Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy and Skin changes. The vascular endothelial growth factor (VEGF) appears to play a key role in the pathogenesis of the syndrome, and its concentrations are deemed to correlate to disease activity. The aim of the present study was to verify whether other biochemical markers including serum free light chains (FLC) and heavy/light chains (HLC) would be of value in monitoring POEMS patients.Fifty-three serum samples were collected from seven POEMS patients at diagnosis and during a follow-up period (range 14–56 months). VEGF was measured using an ELISA method, while FLC and HLC concentrations were measured using Binding Site reagents on a BNII (Siemens) nephelometer.At diagnosis all patients presented high VEGF concentrations, while the κ/λFLC ratio (FLCr) was within the reference range. Four patients had abnormal HLC, HLCκ/HLCλ (HLCr) and FLC values. The relationship between the trend of VEGF and both HLC and FLC during the follow-up was analysed by means of Cohen’s κ coefficient. VEGF and HLC values displayed a significant κ-Cohen (0.537, p=0.002) in all chemotherapy-responder patients while in non-responders it did not. Conversely, in both responders and non-responders, VEGF and FLC values did not attain a significance on κ-Cohen analysis. In three out of four responders HLCr values increased, thus reflecting an improved clinical condition.The findings made in the present study indicate that HLC, either as intact immunoglobulin or as HLCr, may provide useful information, particularly in identifying responders and confirm that the role of FLC is unreliable in monitoring patients with POEMS syndrome.

scholarly journals Analytical bias of automated immunoassays for six serum steroid hormones assessed by LC-MS/MS

2020 ◽  
Vol 30 (3) ◽  
pp. 422-431
Author(s):  
Željko Debeljak ◽  
Ivana Marković ◽  
Vatroslav Šerić ◽  
Vesna Horvat ◽  
Sanja Mandić ◽  
...  
Keyword(s):  
Method Comparison ◽  
Comparison Study ◽  
Serum Samples ◽  
Low Concentrations ◽  
Serum Aldosterone ◽  
Deming Regression ◽  
17 Hydroxyprogesterone ◽  
Method Comparison Study ◽  
Abbott Architect ◽  
Comprehensive Study

Introduction: There is a growing amount of evidence showing the significant analytical bias of steroid hormone immunoassays, but large number of available immunoassays makes conduction of a single comprehensive study of this issue hardly feasible. Aim of this study was to assess the analytical bias of six heterogeneous immunoassays for serum aldosterone, cortisol, dehydroepiandrosterone sulphate (DHEAS), testosterone, 17-hydroxyprogesterone (OHP) and progesterone using the liquid chromatography coupled to the tandem mass spectrometry (LC-MS/MS). Materials and methods: This method comparison study included 49 serum samples. Testosterone, DHEAS, progesterone and cortisol immunoassays were performed on the Abbott Architect i2000SR or Alinity i analysers (Abbott Diagnostics, Chicago, USA). DiaSorin’s Liaison (DiaSorin, Saluggia, Italy) and DIAsource’s ETI-Max 3000 analysers (DIAsource ImmunoAssays, Louvain-La-Neuve, Belgium) were chosen for aldosterone and OHP immunoassay testing, respectively. All immunoassays were evaluated against the LC-MS/MS assay relying on the commercial kit (Chromsystems, Gräfelfing, Germany) and LCMS-8050 analyser (Shimadzu, Kyoto, Japan). Analytical biases were calculated and method comparison was conducted using weighted Deming regression analysis. Results: Depending on the analyte and specific immunoassay, mean relative biases ranged from -31 to + 137%. Except for the cortisol, immunoassays were positively biased. For none of the selected steroids slope and intercept 95% confidence intervals simultaneously contained 0 and 1, respectively. Conclusions: Evaluated immunoassays failed to satisfy requirements for methods’ comparability and produced significant analytical biases in respect to the LC-MS/MS assay, especially at low concentrations.

Comparison of Four Different Assays for Determination of Serum S-100B

2005 ◽  
Vol 20 (1) ◽  
pp. 34-42 ◽  
Author(s):  
L.H.M. Smit ◽  
C.M. Korse ◽  
J.M.G. Bonfrer
Keyword(s):  
Clinical Data ◽  
Reference Values ◽  
Method Comparison ◽  
Correlation Coefficients ◽  
Roc Curves ◽  
Reference Standard ◽  
Healthy Individuals ◽  
Coefficients Of Variation ◽  
Melanoma Patients

Background S-100B determination has been shown to be clinically useful in the management of melanoma patients. After the development of a test for determination of the isoforms S100-A1B and S100-BB in serum (S-100B), several sensitive assays for the detection of serum S-100B have become available. We compared four S-100B assays, two automated (LIAISON®Sangtec®100 and Elecsys®S100) and two manual ones (Sangtec®100 ELISA and CanAg S100 EIA), with respect to clinical data, reference values and correlation. Methods In a total of 280 samples from 155 melanoma patients and 98 healthy individuals S-100B values were measured simultaneously with the different assays. Results The inter and intra coefficients of variation were best for the automated assays. The functional sensitivity of both manual assays was 0.15 μg/L. Method comparison revealed satisfactory correlation coefficients of 0.9 or higher, but the slopes ranged from 0.29 to 3.36. Except for the Sangtec®100 ELISA, the linearity between the assays was acceptable. The overall sensitivity for melanoma ranged from 37% (Elecsys®S100) to 47% (LIAISON®Sangtec®100) and the sensitivity increased with stage. ROC curves showed the best accuracy for the LIAISON®Sangtec®100 assay. Conclusions All assays gave satisfactory results, but it is advisable to improve the performance of the manual assays for better sensitivity. Agreement about an international reference standard is needed.

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