实验诊断学(英文版)第一章.ppt

1、Chapter 1 General of Clinical Laboratory,LI Ping,General of clinical laboratory,Principles to clinical laboratory The interpretation of laboratory testsThe ethical practice,Principle to clinical laboratory,ResponsibilitiesCollection of Information Collection of Specimens(Informed consent、Adequate pr

2、ivacy)Performance of Test Reporting of Result Storage and Retention of Medical RecordsAccess to Medical Records,Responsibilities,The patient-assurance the quality and integrality of the service Colleague and professional-maintain professional reputation,aim to contribute the advancement of professio

3、n Society-contribute to the general well-being of society;comply with relevant laws and regulations of professional activities.,Collection of information,Identify adequately patients and specimens Enable the test to be correctly interpreted Other legitimate purposes,Performance of the test,Accredita

4、tion program,Patients interests,Process standard,Works with high skill and competence,Good performance of tests,Reporting of Result,Test results are confidential unless disclosure is authorized.Report the results correctly and timelyProvide the consultation about the selection and interpretation of

5、tests properly,Access to Medical Records,clinician requesting the test;the patient;laboratory and hospital staff if required for the management of the patient;other authorized individuals.When a request is made for access to test results by an authorized person,the laboratory must first satisfy itse

6、lf as to the identity of the person making the request.,Who?,INTERPRET LABORATORY TEST,Select test,Patients prepare for sampling,Collect specimen,Pre-process of specimen,Analyze specimen,Check、report result,Make clinical decision,Biological variability,improper or inconsistent preparation,Improper o

7、r inconsistant Collection,Improper provision,suboptimum selection,Analytical variabilty,Inadequate RVs,Minimize variability No confusion and misunderstanding about test results,Testing Cycle,Biologic variatinon,Endogenous biorhythms for physiologic parameters,Different constitutional factors and lif

8、estyle among subjects,within-subject variation,subject-to subject variation,Biological variation,Width of the tests Referenc interval(RI),the diagnostic efficiency of a laboratory test,Biological rhythmsConstitutional factors Extrinsic factors,Three types of Biological rhythms,Biologic variation,end

9、ogenous biorhythms for physiologic parameters,Different constitutional factors and lifestyle among subjects,within-subject variation,subject-to subject variation,Biological variation,Width of the tests Referenc interval(RI),the diagnostic efficiency of a laboratory test,Biological rhythmsConstitutio

10、nal factors Extrinsic factors,Biologic variabilty Constitutional factor,infants,children,adults,elderly,rapid physiologic changes、hemolysis、bilirubin,Plasma protein enzyme sex hormones,constant until menopause in women and middle age in men,age-related differences in nutrition、intercurrent disease,A

11、gespecific reference limits,age,Age,Biologic variabilty Constitutional factor,Genetic heterogeneity,phenotypic differences,Different concentration of analyte,Different reactivity towards nucleic acid probes and antibodies,false-negative,Misleading,Genetic heterogeneity,Biologic variabilty-Extrinsic

12、Factors,vascular interstitial space,supine,stand,H2OSmall analyte,plasma volume,Concentration of nondiffusibl analyte,homeostasis of vascular tone,rennin aldosterone catecholamines,Posture,Biologic variabilty Extrinsic Factors,shifts in plasma waterglomerular filtration rate urine productionrelease

13、of macromolecules from cells and tissues,Exercise,Biologic variabilty-Extrinsic Factors,meal related fasting related Recommendation:duration of fasting before specimen collection is typically 12 hours,TGTCBUNGLU.,LacAcetone Glucagons.,Diet,Biologic variabilty Extrinsic Factors,Types of Interference

14、Analytical interference Physiologic interferenceRecommendation Recognize drugs potential for occurrence,withdraw medications before sampling whenever possible,Evaluat any suspicious results in light of a subjects medication history.,Drug,Biologic variabilty-Extrinsic Factors,plasma volume,erythrocyt

15、e mass,plasma protein synthesis,altered distribution of cardiac output,endocrinologic changes,hyperventilation,Pregnancy,Biologic variation-summary,Biological rhythms Circadian,Ultradian,Infradian rhythmsConstitutinal factors Gender,age,geneExtrinsic factors Posture,Exercise,Diet,Drugs,Pregnancy,Caf

16、feine,Alcohol use,Oral Contraceptives,Intercurrent Illness,Establish and validate RVs,Establish clinical performance characteristics,Why?,Help clinician to select the most effective tests and testing strategies Help clinician to translate laboratory results into a probability statement Help the labo

17、ratory director to focus the resources of the laboratory on tests with the highest clinical relevance,How?,Collect data,phase II and phase III clinical trials,Establish and validate RVs,How to assure the validity of the parameters derived from clinical trials?Use gold standard to define every subjec

18、ts status A broad spectrum of healthy and diseased subjects,include patients with a wide range of clinical presentations.CIs should be calculated for all the parameters that are estimated.When new test compares with the old test,assure sample of patients large enough and data exactly.,?,Sensitivity

19、and Specificity,Sensitivity and Specificity,Express the probability that a diseased subject will have an abnormal result Express the probability that a nondiseased patient will have a result within the RI,Sensitivity(Se)=TP/(TP+FN),Specificity(Sp)=TN/(TN+FP),Predictive Value,The probability that a s

20、ubject with a positive test result truly has the disease The probability that a subject with a negative test result truly is healthy.PVs are only accurate when the test is applied to populations with a disease prevalence that is similar to that of the study sample.,PV+=TP/(TP+FP),PV-=TN/(TN+FN),Note

21、,ROC Curves,What is ROC curve used for?Determine the most efficient decision threshold or cutoff value for a laboratory test.Compare the relative clinical accuracies of different laboratory tests in a particular clinical setting,?,ROC Curves,Likelihood Ratios,LHR express the probability that a parti

22、cular will occur in a diseased subject divided by the probability that the same outcome will occur in a nondiseased subject.For continous variable test,LHRs can be established for different ranges of test results,so the magnitude of a test result provides additional discriminatory power,LHR+=Se/(1-S

23、p)=TP rate/FP rate,LHR-=(1-Se)/Sp=FN rate/TN rate,Likelihood Ratios,TP rate represent benefit of the test,FP rate represents the costs associated with testing,so LHR+represents a cost-benefit ratio.It is similar to LHR-.The LHR+and LHR-allow the direct estimation of the posttest probability of disea

24、se in view of the new information contributed by the test result.,LHR+=TP rate/FP rate,Likelihood Ratios,LHR allow the information from different modalities to be combined in serial diagnostic schemes or“critical pathways”for which overall predictive values can be calculated.,Estimating LHR from ROC

25、 Curves,LHRs for a particular test can also be obtained directly form a ROC curve by evaluating the slopes of the curve in different regions continuous variable test positive/negative test test that classified into more than two intervals,ETHICAL PRACTICE,Ethical practice can be regarded as appropri

26、ate technical practice accompanied by integrity in attitudes and behavior.Medical laboratory services are an integral part of medical services,The same standards and ethical principles that govern the delivery of clinical services will also apply to the delivery of laboratory services.,Definitions,W

27、hy Do We Need Ethics?,ETHICAL PRACTICE,Technically competent service Consultation(select and interpret the tests)Protect the patients interestsConfidentiality Medical ethics exist for the protection of patients,and this protection must not be compromised.,Doctor-Patient Relationship,Common Requireme

28、nts Of Medical Laboratory Ethics,Special Requirements Of Medical Laboratory Ethics,Principles Of Ethics,Autonomy、Beneficence、Nonmaleficence、Justice The ethical standards of those working in medical laboratories are derived from medical ethics and incorporate the same principles.,Medical Ethics,Ethics In Medical Laboratories,Thanks!,