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Objective:To evaluate the performance of aldosterone testing in China through the External Quality Assessment (EQA) and improve the testing quality of aldosterone.Methods:Two kinds of EQA program for aldosterone were carried out in China, one of which is Routine EQA and the other is Trueness verification scheme. Lyophilized sera with 5 concentration levels were used as quality control of Routine EQA. The results were grouped according to the instrument. Target values and the coefficient of variation ( CV) were calculated in each group. Trueness verification scheme was verified by using frozen human sera of 3 concentration levels determined by the reference method, and the bias of each instrument group from the target value was calculated. Results:272 laboratories submitted the testing results, and 91.6% of laboratories used chemiluminescence method. The maximum CV was obtained by radioimmunoassay and liquid chromatography mass spectrometry, and the robust CVs were 14.6%-33.4% and 43.5%-53.9%, respectively. For chemiluminescence methods, the robust group CV was less than 10%. The results of the Trueness verification scheme showed that liquid chromatography mass spectrometry method was the most accurate method, with biases of -7.9%, 8.9% and -0.7% for the three quality controls. Diasorin system had the more accurate results deviated from the target by 58.7%, 7.9% and -2.1%, respectively. The results of other chemiluminescence methods were negatively correlated with the sample concentration, and one of them with a bias of 479%. Conclusions:The accuracy and comparability of aldosterone among laboratories in China are not satisfactory. Reagent manufacturers and laboratories should pay more attention to EQA, with the aldosterone results traceable to SI unit, and improve the test quality of aldosterone.
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Objective To understand the current status of the measurement quality of serum Cystatin C (CysC) in China.Methods The external quality assessment (EQA) data in 2017 were collected from the network platform of National Center for Clinical Laboratories.The EQA data were classified into 8 groups according to different types of diagnostic reagents,each of which was employed by at least 18 users.The robust mean value and robust coefficients of variation (CV) were calculated according to ISO 13528 document in each group.The robust mean value was set as the target value.The total error derived from biological variation was used as the fine (3.8％),moderate (7.6％) and weak (11.4％) criteria in evaluating the pass rates,respectively.The reagents which were employed by more than 50 users were classified into subgroups named as " reagent-analyzer" group according to the used analyzer.The median values and differentials between maximum and minimum value were calculated for each reagent-analyzer subgroup.Results A total number of 710 laboratories submitted their results of CysC measurement during 2017.The fine,moderate and weak pass rates according to the setting criteria were 25.9％ (184/710),55.5 ％ (394/710) and 75.2％ (534/710),respectively.The variations of CysC measurement results of among different reagent-analyzer groups ranged from 1.62％ to 12.27％.Conclusion The quality of CysC measurement of should be improved with nationwide attention.
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Objective To evaluate the commutability of 22 processed materials for serum alanine aminotransferase measurements which were performed in 11 routine assays without and 2 assays with pyridoxal-5′-phosphate.Methods 100 serum specimens were collected in Beijing Hospital,Zhao Yang Hospital and Tong Ren Hospital from May,2017 to August,2017.50 individual specimens together with fresh frozen human serum pools(HSPs), external quality assessment(EQA)materials, commercial calibrators and controls were measured by 11 routine assays without pyridoxal-5′-phosphate.Measurement results of the 50 individual samples were pairwise analyzed by Deming regression for slopes and intercepts, and 95%prediction interval(PI)were calculated to evaluate the commutability of processed materials.Another 50 individual specimens and 22 above-mentioned materials were analyzed by 2 assays with pyridoxal-5′-phosphate as the evaluated methods and internationally recognized reference method as the comparative method.The ordinary linear regression(OLR)and 95% PI were used to identify the commutability of 22 materials.Results The Deming slopes ranged from 0.879 to 1.064 and intercepts from -1.96 to 3.30;the OLR slopes were 0.905 and 0.955 while intercepts were -6.71 and 9.53.The HSPs were commutable for 51/57 and 56/57 assay pairs.The EQA materials, commercial calibrators and controls showed noncommutability from 8/57 to 47/57,38/57 and pairs after that, and from 13/57 to 43/57 assay pairs, respectively.Conclusion The lyophilized materials including EQA materials, commercial calibrators and controls demonstrated poor commutability in different degrees.
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Objective To evaluate the trueness of 13 routine measurements for serum uric acid and the role of reference method in improving harmonization and trueness among routine measurement systems. Methods The research is related to the reagent evaluation.Usingisotope dilution liquid chromatography tandem mass spectrometry ( ID-LC/MS/MS) method as the comparison method, Wako, Sekisui, DiaSys, Maker,Dirui,Leadman,BSBE,Biosina,Mindray,MedicalSystem,LongMarch,and Kehua 13 kinds of uric acid kits were chosen as the evaluation methods with Hitachi 7170A as the analyzer.serum uric acid in 40 fresh frozen serawere collected from clinical laboratory of Beijing hospital in 2014,coveringboth physiological and pathological status ( 80 -940 μmol/L ) .19 kinds of prepared materials and the 40 fronzen sera were measuredby comparison method and evaluation methods and linear regression analysis was made for the results.The performance of evaluation methods was revealed and recalibration was performed on every evaluation methodby the linear regression equation.The variation of percent bias(%) of the uric acid values in 19 preparation materials was compared.Results All test methods demonstrated good precision ( CV0.998, P<0.01) with the comparison method when measuring uric acid values in 40 fresh frozen sera The meanpercent bias was 0.17% ( -3.06% -7.31%).After recalibration, 4 of 19 samples with no matrix effect values percent bias reduced and met the demands of quality ( <4.8%) induced from biological variation.Conclusion All test methods demonstrated good trueness and their calibration traceability was verified.Recalibration using reference method or standard reference materials contributes to harmonization among methods.
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Objective To evaluate the analytical quality of different analytical systems in measuring seven kinds of sero-enzymes consisting of Alanine Aminotransferase(ALT), Aspartate Aminotransferase (AST),γ-Glutamyltransferase(GGT), Lactate Dehydrogenase(LDH), Creatine Kinase(CK), α-Amylase (AMY) and Alkaline Phosphatase(ALP).Methods Data from 2013 routine chemistry external quality assessment (EQA) and Enzymes Trueness Verification(ETV) were collected.1 450 and 165 participating laboratories were selected respectively for investigation.Analytical systems of participating laboratories were classified into 6 kinds,i.e.imported matching system(AI), domestic matching system(AH), systems consisting of imported reagents and corresponding calibrators(BI), systems consisting of domestic reagents and corresponding calibrators ( BH ) , unmatched systems using imported calibrators ( CI ) and unmatched systems using domestic calibrators ( CH ) .Total error, bias and coefficient of variation within laboratories ( CVI) were calculated from the data of 2013EQA and ETV The proportion of laboratories meeting the desirable and the optimal criteria derived from biology variation were analyzedby EXCEL2010 with coincidence rate (CR) above 85% as evaluation criterion.Results The AI and CI occupied more than 70%among six systems, CH occupied approximate 15% and the other systems were less than 10%.The range of the average of ETV′s total errors , EQA′s total errors, absolute value of bias and CVI of seven kinds of sero-enzymes were 6.2%-27.8%, 4.0%-7.0%, 4.2%-25.1% and 3.6%-4.6% respectively. Accuracy, bias and within-laboratory imprecision were judged by CR of ETV′s total errors, ETV′s bias, CVI and EQA′s total errors respectively and comparability between different systems was evaluated.It turned out that the results of analytical systems of enzymes except ALP were comparable, the accuracy of systems of enzymes except AMY, ALP and GGT, LDH of AI, the within-laboratory imprecision of enzymes except LDH, AMY, ALP and AST of AI, CH could meet the desirable criteria.The bias of all systems of seven kinds of sero-enzymes were undesirable.Conclusions The analytical quality of routine testing of seven kinds of sero-enzymes could fulfill the clinical requirement generally in China.
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Objective To evaluate the commutability of certified reference materials, external quality assessment program materials and calibrators for serum glucose measurements which were performed in 24 routine measurement procedures.Methods 35 fresh patient specimens and some reference materials were analyzed by isotope dilution liquid chromatography tandem mass spectrometry ( as the comparative method) and 24 routine measurement procedures (as the evaluated methods).The relationships between the results from the evaluated method and the comparative methods were evaluated to identify the commutability.Results It showed that 5 certified reference materials, 2 trueness verification materials, and 5 calibrators were commutable in all 24 routine measurement procedures.The other samples were displayed the presence of commutability issue in different degrees.Conclusion It is important to pay more attention to the problems brought by commutability of reference materials in clinical laboratory.
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Purpose To evaluate the correlation and consistency of left ventricular ejection fraction (LVEF) obtained by ECG-gated myocardial perfusion SPECT (GMPS) using four formulae (R0-R3) of ECToolbox software and findings on equilibrium radionuclide angiography (ERNA), and to determine the optimal diagnostic thresholds by using the four formulae. Materials and Methods A total of 38 patients with myocardial infarction and 65 patients with suspected coronary heart disease underwent both 99Tcm-MIBI rest GMPS and 99Tcm-RBC ERNA within a week. The LVEF values calculated by ECToolbox R0, R1, R2 and R3 were compared with those obtained by ERNA, and compared with ERNA results, the optimal diagnostic thresholds of the four formulae (R0-R3) were assessed by receiver operating characteristic (ROC) curves. Results The results calculated by the formulae (R0-R3) presented a significant positive correlation with that obtained by ERNA [mean LVEF value by ERNA (54.6±17.5)%, mean LVEF value by formulae R0-R3 (64.1±15.7)%, (56.3±15.1)%, (69.9±17.9)% and (56.7±13.6)%, respectively, r=0.899, 0.898, 0.890, 0.895; P<0.01]. All mean LVEF values calculated by the four formulae were higher than that by ERNA, and the difference was significant (P<0.05). LVEF≥50%obtained by ERNA was considered as normal diagnostic value, the optimal diagnostic thresholds of R0-R3 were 56.5%, 51.5%, 64.5% and 52.5%, respectively. Conclusion The results calculated by R0, R1, R2 and R3 in the ECToolbox software and that by ERNA show significant correlation and difference for the assessment of LVEF. Thus it is advisable to stick to one formula in the follow-up of each patient and select correspondent threshold in the clinical diagnosis.
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Objective To evaluate the efficacy and safety of linezolid in empirical treatment of methicillin-resistant Staphylococcus (MRS) pneumonia. Methods One hundred and thirty-five hospitalized patients with MSR pneumonia receiving linezolid from April 2009 to October 2010 were enrolled in this retrospective cohort study, and all subjects were assigned to two groups: 75 cases with empirical treatment (linezolid 0. 6 g by infusion q12h at admission) , and 60 cases with objective treatment (linezolid after the sputum culture). The severity score, clinical effect and adverse effect were observed, and the therapeutic effects in patients with high risk factors were especially evaluated. SPSS13.0 software was used for statistical analysis. Results The scores were decreased significantly after finishing therapeutic causes for 3 and 7 days in both groups (tempirical =12.29 and 16.53, tobjective =9.36 and 11.49, P 0.05 ). In the patients with high risk factors, the effective rates of two groups were 86. 8% (33/38) and 63. 6% (14/22) , and the difference was significant (x2 =4.42, P 0. 05). Conclusion Linezolid can be used as empirical treatment for MRS pneumonia with rapid symptoms relieve and high efficacy, especially for patients with high risk.
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Objective To develop a candidate reference method for the measurement of serum glucose based on isotope dilution liquid chromatography tandem mass spectrometry(ID-LC/MS/MS)Methods An internal standard [~(13)C_6]glucose was added to serum samples and equilibrated with endogenous glucose.Serum proteins were removed by a precipitation with anhydrous ethanol.Serum glucose and the internal standard were then reacted with 1-phenyl-3-methyl-5-pyrazolone and the formed derivatives were analyzed by liquid chromatography tandem mass spectrometry with multiple reaction monitoring(MRM).The method was calibrated with bracketing calibrators and serum glucose concentrations were calculated by comparing the peak area ratios of samples with that of the calibrators.Results The within-run,between-run and total coefficients of variation averaged 0.36%,0.47%and 0.61%,respectively.The analytical recoveries ranged from 99.0% to 100.9%.Results of analyzing the certified reference material SRM 965a showed an average biases of-0.20%.Conclusions An ID-LC/MS/MS method for measuring serum glucose has been developed.The method is highly precise and accurate and may be used as a candidate reference method.
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Objective To develop a candidate reference method for the measurement of creatinine in human serum based on isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS). Methods An isotopically labeled internal standard [<'2>H<,3>] creatinine was added to the serum sample and equilibrated with the endogenous creatinine. The samples were treated with anhydrous ethanol to remove proteins by precipitation. After being washed with chloroform for further clean-up, the samples were analyzed by LC/MS/MS. Serum creatinine was quantified by a bracketing calibration. Results The within-run, between-run and total coefficients of variation ranged from 0.52% to 0.61%, 0.11% to 0.59% and 0.61% to 0.83%, and the averages were 0.57%, 0.43% and 0.73%, respectively. The analytical recoveries ranged from 99.09% to 101.13% with an average of 100.3%.The results of analyzing the certified reference material SRM 909b (Level Ⅰ and Ⅱ) and SRM 967b showed biases of less than 0.4%. Conclusions An ID-LC/MS/MS method for measuring serum creatinine has been developed. The method is highly precise and accurate and may be used as a candidate reference method for serum creatinine measurements.
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Objective To exlore the influence of internal quality control and external quality control assessment(EQA) resulting from applicability of control samples in measurement of whole blood viscosity (WBV) through the analysis and comparison of applicability of 1 non-Newtonian fluid internal quality control sample in 3 viscometers. Methods Viscometer B, C and D were used to measure WBV of 30 blood samples in parallel under the shear rate(SR) of 1 s-1,30 s~(-1) and 200 s~(-1), then the blood SR-WBV curves of 3 viscometers were drawn according to the results. At the same time, viscometers B, C and D were used respectively to determine the WBV of control A 10 times in one day, then the control A SR-WBV curves were mapped. Three viscometers were used to measure the manufactory control samples and control A 5 times in one day for 4 days. Four groups of daily values of manufactory control samples and control A of each instrument were used to carry out F test to calculate whether 4 daily values are difference. Finally, the control A was dispensed in 49 laboratories nationwide chosen for measurement. On the basis of viscometer used, 20 laboratories were classified as group B, 20 laboratories were classified as group C and 9 laboratories were classified as group D. Then the data under SR of 1 s~(-1) were analyzed to calculate the coefficient of variation (CV) in the group. Results There was significant difference among the WBV of blood samples measured by the viscometers B, C and D. The results under SR of 1 s~(-1) declined in turn, and they were highest under SR of 30 s~(-1) followed by the values of viscometer D and B and they were (8.14±0.75), highest under SR of 30 s-1 followed by the values of viscometer B and D, and they were (7.35±0.07), daily values of manufactory control and control A of each instruments in four groups were compared. Under SR of 1 s~(-1), there was no difference between daily values of manufactory control and control A in viscometer B (F = 2.63, 1.37, P > 0.05), and there was no difference of daily values of manufactory control among viscometer C and D (F = 0.33,3. 14, P > 0.05), but significant daily difference existed when control A was tested by viscometer C and D (F = 5.76, 8.00, P < 0.05). Under SR of 30 s~(-1), there was no difference of daily values of manufactory control among 3 viscometers(F =0.31, 0.18, 2.26, P >0.05), and there was no difference of daily values of control A among 3 viscometers' (F = 1.03, 1.83, 2.40, P > 0.05); Under SR of 200 s~(-1), there was no difference of daily values of manufactory control among 3 viscometers (F =2.59, 0.68, 2.96, P > 0.05), and there was no difference of daily values of control A among 3 viscometers (F=2.31, 3.01, 2.28, P>0.05). When control A was tested under SR of 1 s~(-1) in 49 laboratories nationwide, the WBV values in groups of viscometer B, C and D were (18.47±1.30), (11.17±2.38), viscometer D and C were 63.75% and 21.3%. Conclusions Control A could fully mimic the properties of whole blood steadily on viscometer B, but partially mimic viscometer C and D, so the control A is most appropriate for viscometer B. Because current non-Newtonian fluid internal quality control could mimic rheological properties of whole blood under specifically conditions, laboratories should evaluate the consistent degree between control and whole blood, only the candidates which can mimic the properties of whole blood approximately could be chosen as quality control of WBV. When third-party control is chosen to be samples of EQA, its applicability should be in consideration. Pretest should be performed adequately to define applicability of third-party control, so as to reduce the difference among laboratories due to applicability of control and reflect detection quality of laboratories exactly.
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Objective To evaluate the matrix effects in serum urea measurements of external quality assessment(EQA)materials and commercial reference materials(calibrators or controls)on enzymatic methods and to verify the trueness of the enzymatic methods.Methods The Clinical and Laboratory Stadards Institute(CLSI)EP 14-A2 protocol was used for the evaluation of matrix effect.An isotope dilution gas chromatography mass spectrometry method was used as the comparative method.Twenty five fresh patient serum samples,15 EQA materials and 13 calibrators or controls were analyzed with 7 enzymatic methods (evaluated methods)and the comparative method and results were processed according to the protocol. The trueness of the evaluated methods were also assessed by comparing the fresh sample results obtained with the evaluated and comparative methods.Results Eight of 15 EQA materials and 3 of 13 calibrators or controls showed no matrix effects on all the 7 routine methods.One processed sample showed matrix effect on all the routine methods.Method dependent matrix effects of other materials were observed on other materials.Calibration biases were also observed on some enzymatic methods.Conclusions Matrix effects and calibration bias have been observed in serum urea measurements.Continued efforts are needed for improving the accuracy and the comparability of serum urea measurements.
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Objective To evaluate the matrix effect of processed materials in serum total glycerol measurement and to assess the accuracy of routine test systems.Methods With an isotope dilution liquid chromatography tandem mass spectrometry method as the comparative method，matrix effects of 28 processed materials on 8 routine test systems were evaluated ccording to the NCCLS EP 14 protocol.The processed materials and 20 flesh patient specimens were analyzed with both the comparative method and each of the evaluated methods and results obtained with the two methods were plotted.Two-tailed 95% prediction intervals for the mean of the flesh patient specimen were computed and results on the processed aterials were compared with these intervals for evaluation of matrix effect.Results with the two methods on fresh samples were also compared for assessment of the accuracy of the routine test systems.Results Some of the processed samples showed matrix effects on some of the routine test systems.The observed matrix effects were system-specific and aused either positive or negative biases.Calibration biases were also observed on some test systems.Conclusion Matrix effect and calibration bias have been observed in serum total glycerol measurements.Continued efforts are needed for improving the accuracy of serum total glycerol measurements.
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Objective To develop a candidate reference method for the measurement of urea in human serum based on isotope dilution/gas chromatography/mass spectrometry.Methods [13C,15N2]Urea used as internal standard Was added to the serum sample and equilibrated with endogenous nonlabeled urea.The serum samples were treated with anhydrous ethanol to emove proteins by precipitation.The serum urea and labeled urea were converted into a trimethylsilyl derivative of 2-hydroxypyrimidine and analyzed by gas chromatography/mass spectrometry system with selected ion monitoring.The concentration of serum ureaWas calculated by the theory of bracketing method.Results The average value of within-run oefficient of vailation(CV),between-run CV and total CV of the procedure were 0.38%(ranged from 0.12%to 0.47%),O.62%(ranged form 0.49% to 0.87%)and 0.73%(ranged from 0.51% to 0.93%).Respectively.The analytical recoveries ranged from 99.37% to 100.95%.The resuhs of analyzing the certified refefence material SRM909b(Level Ⅰand Ⅱ)showed a bias less than 0.2%.Conclusion The procedure for measuring urea in serum is a highly accurate and precise method and can be used as a candidate reference method for serum urea assays.