Diabetes is a worldwide epidemic disease in the twenty-first century.The most danger of diabetes is its complications which are the major cause of morbidity and mortality in diabetic patients.The development and progression of diabetes complications are directly associated with blood glucose levels,Hemoglobin A1c is not only the gold standard for the long-term blood glucose control of diabetic patients,but also the World Health Organization (WHO) recommended diagnosis of diabetes.Thus,a question has been raised:how to improve the comparability of hemoglobin A1c results meet clinical needs? At least four points should be taken in determining hemoglobin A1c:(1)Understand the interference factors; (2)Choose scientific and practical methodologies; (3)Standardized operation; (4)Regularly monitor the quality of testing results.

Objective To investigate the stability of glycated hemoglobin HbA1c in whole blood sample measured by Tosoh G7, Roche/Hitachi 7170A and NycoCard READER Ⅱ under different storage conditions. Methods Three whole blood samples (EDTA anticoagulated) with different glycated hemoglobin levels and one whole blood sample (heparin anticoagulated) were collected and stored at -80 ℃, -20 ℃, 4 ℃,room temperature(15 -25 ℃), and 37 ℃ HbA1c was analyzed by each method on days 1, 2, 5, 7, 9, 14, 21,28, 35, 42, 49, 56, 63 and 70 respectively. Results The results of sample stored at -80 ℃ appear to be stable for Tesoh G7 and Roche/Hitachi 7170A method. The coefficients of variation (CV) for Tosoh G7 was 0.54%-1.22%. The CV for Roche/Hitachi 7170A was 0.86% -1.82%. When samples was detected with Tosoh G7 method, the results was consistent when the sample was stored at -20 ℃ for 14 days, 4 ℃ for 63 days, room temperature for 5 days, and 37 ℃ for less than 1 day. When samples was detected with Roche/Hitachi 7170A method, the results was consistent when the samples was stored at -20 ℃ for 21 days, 4 ℃ for 42 days, room temperature for 7 days, and 37 ℃ for less than 1 day. The NycoCard READER Ⅱ showed stability at 4 ℃ for 9 days, and room temperature for less than 1 days. Conclusions The stability of whole blood samples is dependent on different methods. Storage time under different temperatures is different.

Objective To investigate the value of the joint detection of Troponin T(TnT),highsensitivity C-reactive protein (hs-CRP) and N-terminal probrain natriuretic peptide (NT-proBNP) for the clinical diagnosis of acute coronary syndrome(ACS) in elderly patients.Methods The adequate serum samples were collected in each group:unstable angina (UA) (49 cases),non-ST segment elevations myocardial infarction(NSTEMI) (48 cases),acute myocardial infarction(AMI) (37 cases)and healthy control (45 cases).The levels of TnT and NT-proBNP were measured by electrochemiluminescent double antibody sandwich method,and hs CRP by immune transmission turbidity.The roles of individual and joint detection of the three indicators were analyzed by ROC curve and Logistic regression model.Results Except for TnT in UA group,the serum TnT,NT-proBNP and hs-CRP levels were significantly higher in three ACS groups than in healthy control group (P＜0.05).The largest areas under the ROC curve (AUC) of individual TnT,NT-proBNP,hs-CRP testing and the joint detection for UA were 0.583±0.059,0.786±0.047,0.620±0.058 and 0.787±0.046,for NSTEMI were 0.967±0.022,0.978±0.015,0.897±0.032 and 0.991 ±0.009,for AMI were 0.971 ± 0.024,0.961 ± 0.021,0.874 ± 0.043 and 0.999 ± 0.002,therefore,the area under the ROC curve of the joint detection was increased to some degree as compared with individual TnT,NT-proBNP,hs-CRP testing.Similarly,the best sensitivity and specificity of individual TnT,NT-proBNP,hs-CRP testing and the joint detection for UA were 16.7％ and 100.0％,54.2％ and 91.1％,54.2％ and 75.6％,50％ and 95.6％; for NSTEMI were 93.5％ and 100.0％,95.7％ and 97.8％,67.4％ and 97.8％,95.7％ and 100.0％; for AMI were 94.1％ and 100.0％,91.2％ and 97.8％,67.8％ and 97.8％,100.0％ and 97.8％,respectively.Conclusions Joint detection of TnT,NT-proBNP,hs-CRP can significantly improve the diagnosis of UA; for NSTEMI and other AMI,it can be achieved the optimism of sensitivity and specificity,but its effect of distinguishing NSTEMI and AMI is little.

This article summarized recent correlative literatures focusing on international standards on glycated hemoglobin.The basic concept,determination of glycated hemoglobin,the present review in laboratory measurement and metrological traceability was introduced.The international community has established reference system and metrological traceability to the International System of Units on HbA1c.Determination in glycated hemoglobin is still in incipient stage in our country.Both clinical laboratorians awareness and clinical determination need to be strengthened.

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.

Objective To prepare the serum reference materials for total thyroxine .Methods Individual blood samples were collected from 13 healthy donors (7 males and 6 females) aged from 20 to 50 years old, and the sera were separated and mixed into 4 serum pools according to the concentration of thyroxine.The materials were tested for homogeneity and stability using routine methods .The method of isotope dilution liquid chromatography tandem mass spectrometry ( ID-LC/MS/MS) was used to determine the concentration of thyroxine .The candidate reference materials were also measured by four conventional methods to analyze the commutability of the materials .Results It showed that the four candidate reference materials were homogeneous and commutable in four conventional methods and they were tested to be stable for at least 1 year at -70 ℃using the isochronous stability study .The certified values ( reference value ± expanded uncertainty ,nmol/L) were:75.9 ±1.8,105.3 ±2.2,114.7 ±2.1 and 187.4 ±2.9.Conclusions Certified reference materials for serum thyroxine have been prepared .These materials have been approved to be the Certificate Reference Materials of GBW 09127,GBW 09128,GBW 09129 and GBW 09130.

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 ( CV<1.75) and good correlation (R2 >0.998, 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.

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.

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.

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.