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IFCC primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of enzymes at 37 °C. Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase

Abstract This paper is the second in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of γ-Glutamyltransferase; Part 7. Certification of Four Reference Materials for the Determination of Enzymatic Activity of γ-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37°C. A document describing the determination of preliminary reference values is also in preparation. The procedure described here is deduced from the previously described 30°C IFCC reference method (1). Differences are tabulated and commented on in Appendix 3.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase.

Abstract This paper is the fourth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of γ-Glutamyltransferase; Part 7. Certification of Four Reference Materials for the Determination of Enzymatic Activity of γ-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37°C. A document describing the determination of preliminary upper reference limits is also in preparation. The procedure described here is deduced from the previously described 30°C IFCC reference method (1). Differences are tabulated and commented on in Appendix 2.

Generation of a New Cystatin C–Based Estimating Equation for Glomerular Filtration Rate by Use of 7 Assays Standardized to the International Calibrator

BACKGROUND Many different cystatin C-based equations exist for estimating glomerular filtration rate. Major reasons for this are the previous lack of an international cystatin C calibrator and the nonequivalence of results from different cystatin C assays. METHODS Use of the recently introduced certified reference material, ERM-DA471/IFCC, and further work to achieve high agreement and equivalence of 7 commercially available cystatin C assays allowed a substantial decrease of the CV of the assays, as defined by their performance in an external quality assessment for clinical laboratory investigations. By use of 2 of these assays and a population of 4690 subjects, with large subpopulations of children and Asian and Caucasian adults, with their GFR determined by either renal or plasma inulin clearance or plasma iohexol clearance, we attempted to produce a virtually assay-independent simple cystatin C-based equation for estimation of GFR. RESULTS We developed a simple cystatin C-based equation for estimation of GFR comprising only 2 variables, cystatin C concentration and age. No terms for race and sex are required for optimal diagnostic performance. The equation, [Formula: see text] is also biologically oriented, with 1 term for the theoretical renal clearance of small molecules and 1 constant for extrarenal clearance of cystatin C. CONCLUSIONS A virtually assay-independent simple cystatin C-based and biologically oriented equation for estimation of GFR, without terms for sex and race, was produced.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C.

Abstract This paper is the eighth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes; Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase; Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase; Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase Part 6. Reference procedure for the measurement of catalytic concentration of γ-glutamyltransferase; Part 7. Certification of four reference materials for the determination of enzymatic activity of γ-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase at 37°C. The procedure described here is deduced from the previously described 30°C IFCC reference method. Differences are tabulated and commented on. Clin Chem Lab Med 2006;44:1146–55.This paper is the eighth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes; Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase; Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase; Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase Part 6. Reference procedure for the measurement of catalytic concentration of gamma-glutamyltransferase; Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase at 37 degrees C. The procedure described here is deduced from the previously described 30 degrees C IFCC reference method. Differences are tabulated and commented on.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase accord.

Abstract This paper is the seventh in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of γ-Glutamyltransferase. A document describing the determination of preliminary reference values is also in preparation. The certification of the catalytic activity concentrations as determined by the recently elaborated IFCC primary reference methods at 37°C of four enzyme preparations, namely IRMM/IFCC 452 γ-glutamyltransferase), IRMM/IFCC 453 (lactate dehydrogenase 1), IRMM/IFCC 454 (alanine aminotransferase) and IRMM/IFCC 455 (creatine kinase) is described. Homogeneity data were derived from previous results. Stability was assessed using recently obtained data as well as data from previous stability studies. The collaborative study for value assignment was performed under a strict quality control scheme to ensure traceability to the primary reference method. Uncertainty of the materials was assessed in compliance with the Guide to the Expression of Uncertainty in Measurement. The certified values obtained at 37°C are 1.90 μkat/l ± 0.04 μkat/l (114.1 U/l ± 2.4 U/l), for γ-glutamyltransferase, 8.37 μkat/l ± 0.12 μkat/l (502 U/l ± 7 U/l), for lactate dehydrogenase 1, 3.09 μkat/l ± 0.07 μkat/l (186 U/l ± 4 U/l), for alanine aminotransferase and 1.68 μkat/l ± 0.07 μkat/l (101 U/l ± 4 U/l), for creatine kinase. The materials are intended for internal quality control as well as for the evaluation of test systems as required by recent European Union legislation. Furthermore, the materials can be used to transfer accuracy from a reference method to a routine procedure provided the procedures exhibit the same analytical specificity and the certified materials are commutable.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase.

Abstract This paper is the third in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of γ -glutamyltransferase; Part 7. Certification of Four Reference Materials for the Determination of Enzymatic Activity of γ-Glu tamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37°C. A document describing the determination of preliminary upper reference limits is also in preparation. The procedure described here is deduced from the previously described 30°C IFCC reference method (1). Differences are tabulated and commented on in Appendix 1. Clin Chem Lab Med 2002; 40(6):643648

IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37( C. Part 1: The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes

This paper is the first in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and with the certification of reference preparations. Other parts deal with: Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic fication of Four Reference Materials for the Determination of Enzymatic Activity of y-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37 degrees C. A document describing the determination of preliminary reference values is also in preparation.

IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37C. Part 6. Reference Procedure for the Measurement of Catalytic Concentration of γ-Glutamyltransferase

Abstract This paper is the sixth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 7. Certification of Four Reference Materials for the Determination of Enzymatic Activity of γ-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37°C A document describing the determination of preliminary upper reference limits is also in preparation. The procedure described here is deduced from the previously described 30°C IFCC reference method (1). Differences are tabulated and commented on in Appendix 1.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C: International Federation of Clinical Chemistry and Laboratory Medicine (IFCC): Scientific Division, Committee on Reference Systems for Enzymes (C-RSE): Part 8. Reference procedure for the measurement of catalytic concentration of α-amylase: [α-Amylase: 1,4-α-D-glucan 4-glucanohydrolase (AMY), EC 3.2.1.1]

Abstract This paper is the eighth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37°C and the certification of reference preparations. Other parts deal with: Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes; Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase; Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase; Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase Part 6. Reference procedure for the measurement of catalytic concentration of γ-glutamyltransferase; Part 7. Certification of four reference materials for the determination of enzymatic activity of γ-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase at 37°C. The procedure described here is deduced from the previously described 30°C IFCC reference method. Differences are tabulated and commented on. Clin Chem Lab Med 2006;44:1146–55.This paper is the eighth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes; Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase; Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase; Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase Part 6. Reference procedure for the measurement of catalytic concentration of gamma-glutamyltransferase; Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase at 37 degrees C. The procedure described here is deduced from the previously described 30 degrees C IFCC reference method. Differences are tabulated and commented on.

A two-center evaluation of the blood gas Immediate Response Mobile Analyzer (IRMA)

Abstract The Immediate Response Mobile Analyzer (IRMA) is a selective and portable point-of-care testing (POCT) blood gas, electrolyte and hematocrit (Hct) analyzer. The overall analytical performance was evaluated in a two-center study involving two Italian hospital laboratories, following the guidelines suggested by the manufacturer (based on the NCCLS protocol), after a preliminary evaluation of their formal validity. The IRMA was compared to the analyzers used in the routine laboratory as reference. The considered parameters were pH, pO2, pCO2, Na+, K+, ionized calcium and Hct. When using the aqueous quality control material provided by the manufacturer most of the parameters showed good precision, with the exception of pCO2 and pO2 that showed high CVs on two of the three levels of the aqueous control. We could demonstrate that this imprecision was material-related and was reduced when using a different material (blood equilibrated by tonometry). With tonometred blood for pO2 and pCO2 and the aqueous material for the remaining parameters the CVs were all below 5%, ranging from 0.08% to 2.8%. The IRMA results correlated adequately with the comparison instruments, with the exception of sodium and ionized calcium where contradictory results were obtained in the two centers.