The goal of clinical laboratories is to produce accurate information for clinical decision making in medicine. More than half of the medical decisions made depend on clinical laboratory tests.
Patient safety represents an important and critical problem for laboratories. They need to assure that the information they deliver to physicians is accurate, and therefore safe for clinicians to use. Endogenous compounds can interfere with laboratory tests, decreasing accuracy and threatening patient safety. Elevated bilirubin (bilirubinemia) and elevated lipids (lipemia) are common conditions that cause significant interferences with laboratory results. Clinicians depend on laboratories to detect these endogenous interferences. Laboratories must have a means to detect these endogenous interferences, make decisions about reporting results, and evaluate their impact.
Most clinical pathology books provide only an abbreviated introduction to the subject, or provide a long list of references, without the necessary foundation for evaluating their significance. Package inserts typically provide scant information. This book provides the empirical and theoretical foundation for these interferences, describes the clinical settings where they occur, and explains their evaluation and detection, allowing the laboratory to interpret the available data on interferences and make the appropriate decision to effectively report test results while protecting patient safety.
Inhaltsverzeichnis
1;Preface;7 2;1 Accuracy Goals for Laboratory Tests;13 2.1;1.1 Accuracy and Precision;13 2.1.1;1.1.1 Definition;13 2.1.2;1.1.2 Imprecision as a Form of Error;14 2.2;1.2 Types of Error;14 2.2.1;1.2.1 Bias;14 2.2.2;1.2.2 Impact of Bias;16 2.3;1.3 Interference as a Type of Bias;18 2.4;1.4 References;20 3;2 Nature of Interferences;23 3.1;2.1 Definition;23 3.2;2.2 Nature of Interferences;23 3.3;2.3 Instrumentation;24 3.4;2.4 The Chemistry of the Absorbance of Light;27 3.5;2.5 References;32 4;3 The Nature of Icteric Interference;33 4.1;3.1 Source Information on Bilirubin Interference;33 4.2;3.2 Allen Correction as a Source of Bilirubin Interference;33 4.3;3.3 Bilirubin Interference with Oximetry;34 4.3.1;3.3.1 Co-oximetry Interference;36 4.3.2;3.3.2 Pulse Oximetry;37 4.3.3;3.3.3 Cerebral Oximetry;38 4.3.4;3.3.4 Interference with Methemoglobin;39 4.4;3.4 Chemical Reactions as a Cause of Bilirubin Interference;40 4.4.1;3.4.1 Bilirubin Reaction with Creatinine Methods;41 4.4.2;3.4.2 Bilirubin Reactions with Peroxidase Methods;43 4.5;3.5 References;44 5;4 The Nature of Lipemic and Turbidity Interferences;47 5.1;4.1 Types of Interferences;47 5.2;4.2 Lipemia Causes Turbidity;48 5.3;4.3 Lipemia Interference Mechanisms;49 5.3.1;4.3.1 Light Scattering;49 5.3.2;4.3.2 Lipoprotein Particles;52 5.3.3;4.3.3 Intralipid and Lipemia Simulation;54 5.3.4;4.3.4 Empirical Studies in Lipemia Turbidity;55 5.4;4.4 Lipoprotein Particles and Lipemia;56 5.5;4.5 References;57 6;5 Measurement of Interference;59 6.1;5.1 A Typical Commercial Study;59 6.2;5.2 Guidelines for Interference Studies;60 6.3;5.3 Bilirubin;61 6.4;5.4 Intralipid;62 6.5;5.5 Procedure to Make Five Concentrations;64 6.6;5.6 Interference Criteria;64 6.7;5.7 Data Analysis;66 6.8;5.8 References;72 7;6 Origin of Icteric Samples;75 7.1;6.1 The Origin of Bilirubin;75 7.2;6.2 Bilirubin Toxicity;77 7.3;6.3 Transport of Bilirubin in the Blood;77 7.4;6.4 Uptake of Bilirubin by the Liver;78 7.5;6.5 Clinical Aspects of Bilirubin;78 7.6;6.6 Neo
natal Jaundice;79 7.7;6.7 Cholestasis;81 7.8;6.8 Hepatitis;82 7.9;6.9 Alcoholic Liver Disease;82 7.10;6.10 Hemolysis;83 7.11;6.11 Drug Induced Hyperbilirubinemia;83 7.12;6.12 Summary;84 7.13;6.13 References;84 8;7 Impact of Icterus;87 8.1;7.1 Introduction;87 8.2;7.2 Estimated Impacts Based on Interference Studies;87 8.3;7.3 Differential Interference with Different Bilirubin Isoforms;89 8.4;7.4 Non-spectrophotometric Icterus Interference;91 8.5;7.5 Resolving Icterus Interference;92 8.6;7.6 Summary;93 8.7;7.7 References;93 9;8 Origin of Lipemia and Turbidity;95 9.1;8.1 Lipoprotein Pathways;95 9.2;8.2 Classification of Hypertriglyceridemia;97 9.2.1;8.2.1 Frederickson Classification of Dyslipidemias;97 9.2.2;8.2.2 Obesity, Metabolic Syndrome and Diabetes;99 9.2.3;8.2.3 Alcohol;100 9.2.4;8.2.4 Nonalcoholic Fatty-liver Disorder;101 9.2.5;8.2.5 Medications;101 9.2.6;8.2.6 HIV Infection;101 9.2.7;8.2.7 Renal Disease;102 9.3;8.3 References;103 10;9 Impact of Lipemia/Turbidity;105 10.1;9.1 Introduction;105 10.2;9.2 Estimated Impacts Based on Interference Studies;107 10.2.1;9.2.1 Interference by Light Scattering;107 10.2.2;9.2.2 Interference by Volume Displacement;108 10.2.3;9.2.3 Interference by Lipid Partitioning;111 10.3;9.3 Summary;111 10.4;9.4 References;111 11;10 Endogenous Interferences in Clinical Laboratory Tests: Icteric, Lipemic and Turbid Samples;113 11.1;10.1 Interference Indices;113 11.2;10.2 Generating Interference Indices;113 11.2.1;10.2.1 Preparation of Standards;114 11.2.2;10.2.2 Data Collection and Deconvolution of Non-Target Interferences;115 11.2.2.1;10.2.2.1 Subtraction Using Selected Wavelengths;116 11.2.2.2;10.2.2.2 Index Calculation Using Derivative Spectrometry;117 11.2.3;10.2.3 Establishing Indices and Defining Ranges;119 11.3;10.3 Limitations;122 11.4;10.4 Summary;122 11.5;10.5 References;123 12;11 Reporting of Results;125 12.1;11.1 Introduction;125 12.2;11.2 Procedures for Handling Samples with Interference Within the Laboratory;125 12.3;11.3 Repor
ting of Results in Icteric and Turbid Samples;127 12.4;11.4 Autoverification and Reporting Algorithms;128 12.5;11.5 Practical Issues: Education and Implementation;129 12.6;11.6 References;130 13;12 Analyte-dependent Interference;131 13.1;12.1 Complex Interferences;131 13.1.1;12.1.1 Model for Analyte-dependent Interference;132 13.1.2;12.1.2 Examples of Analyte-Dependent Interference;133 13.2;12.2 Statistical Testing for Significance;141 13.3;12.3 Failure to Design the Interference Study;145 13.4;12.4 Advantages of Using Multiple Regression Analysis;145 13.5;12.5 Concluding Remarks;147 13.6;12.6 References;149 14;Index;151
