實(shí)驗(yàn)診斷學(xué)英文版第一章

1、General of clinical laboratory,Principles to clinical laboratory The interpretation of laboratory testsThe ethical practice,Principle to clinical laboratory,ResponsibilitiesCollection of Information Collection of S

2、pecimens (Informed consent 、 Adequate privacy) Performance of Test Reporting of Result Storage and Retention of Medical RecordsAccess to Medical Records,Responsibilities,The patient----assurance the qualit

3、y and integrality of the service Colleague and professional -----maintain professional reputation, aim to contribute the advancement of profession Society----contribute to the general well-b

4、eing 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 legiti

5、mate purposes,Performance of the test,Accreditation program,Patients interests,,,Process standard,Works with high skill and competence,,,Good performance of tests,Reporting of Result,Test results are confidential un

6、less disclosure is authorized. Report the results correctly and timelyProvide the consultation about the selection and interpretation of tests properly,Access to Medical Records,clinician requesting the test; the

7、 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 s

8、atisfy itself 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

9、 result,Make clinical decision,,,,,,,,Biological variability ,improper or inconsistent preparation,Improper or inconsistant Collection,Improper provision,suboptimum selection,Analytical variabilty,Inadequate RVs,Minim

10、ize variability No confusion and misunderstanding about test results,Testing Cycle,Biologic variatinon,,Endogenous biorhythms for physiologic parameters,Different constitutional factors and lifestyle among subject

11、s,,,within-subject variation,subject-to –subject variation,,,Biological variation,,,,Width of the test’s Referenc interval (RI),,the diagnostic efficiency of a laboratory test,,,Biological rhythmsConstitutional

12、 factors Extrinsic factors,Three types of Biological rhythms,Biologic variation,,endogenous biorhythms for physiologic parameters,Different constitutional factors and lifestyle among subjects,,,within-subject variati

13、on,subject-to –subject variation,,,Biological variation,,,,Width of the test’s Referenc interval (RI),,the diagnostic efficiency of a laboratory test,,,Biological rhythmsConstitutional factors Extrinsic factor

14、s,Biologic variabilty —— Constitutional factor,,infants,,children,,adults,,elderly,,rapid physiologic changes 、hemolysis 、 bilirubin,,Plasma protein enzyme sex hormones,,,,constant unti

15、l menopause in women and middle age in men,,age-related differences in nutrition 、intercurrent disease,,,,,Agespecific reference limits,age,,,,,Age,Biologic variabilty –Constitutional factor,Genetic heterogeneity

16、,phenotypic differences,,,,,Different concentration of analyte,Different reactivity towards nucleic acid probes and antibodies,,false-negative,,,,Misleading,,,,Genetic heterogeneity,,Biologic variabilty -

17、 Extrinsic Factors,vascular interstitial space,supine,stand,,,H2OSmall analyte,,,,,,,,,,,,,,,,plasma volume,Concentration of nondiffusibl analyte,,,

18、,homeostasis of vascular tone,rennin aldosterone catecholamines,,,,,,,,,,,,Posture,Biologic variabilty – Extrinsic Factors,shifts in plasma waterglomerular filtration rate urine produc

19、tionrelease of macromolecules from cells and tissues,,,,Exercise,Biologic variabilty - Extrinsic Factors,meal related fasting related Recommendation : d

20、uration of fasting before specimen collection is typically 12 hours,TGTCBUNGLU……..,LacAcetone Glucagons……….,Diet,Biologic variabilty – Extrinsic Factors,Types of Interference ——

21、 Analytical interference Physiologic interferenceRecommendation —— Recognize drugs’ potential for occurrence, withdraw medications before sampling whenever possible,

22、 Evaluat any suspicious results in light of a subject’s medication history.,Drug,Biologic variabilty- Extrinsic Factors,,plasma volume,erythrocyte mass,plasma pro

23、tein synthesis,,,,altered distribution of cardiac output,endocrinologic changes,hyperventilation,Pregnancy,Biologic variation-summary,Biological rhythms—— Circadian , Ultradian ,Infradian rhythmsConstitut

24、inal factors—— Gender, age, geneExtrinsic factors—— Posture, Exercise, Diet, Drugs, Pregnancy , Caffeine, Alcohol use, Oral Contraceptives, Intercurrent Illness,Establish and validate RVs,,Estab

25、lish 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

26、Help the laboratory 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 R

27、Vs,How to assure the validity of the parameters derived from clinical trials?Use gold standard to define every subject’s status A broad spectrum of healthy and diseased subjects, include patients with a wide range of

28、 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 and Spe

29、cificity,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/

30、 (TP+FN),Specificity(Sp)=TN/(TN+FP),Predictive Value,The probability that a subject with a positive test result truly has the disease The probability that a subject with a negative test result truly is healthy .

31、 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,ROC Curves,What is ROC curve used for ?D

32、etermine 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

33、 Ratios,LHR express the probability that a particular 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

34、established for different ranges of test results, so the magnitude of a test result provides additional discriminatory power,LHR+ =Se/(1-Sp)=TP rate/FP rate,LHR-=(1-Se)/Sp=FN rate/TN rate,Likelihood Ratios,TP rate repr

35、esent 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 probabili

36、ty of disease 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 “cr

37、itical pathways” for which overall predictive values can be calculated.,Estimating LHR from ROC Curves,LHRs for a particular test can also be obtained directly form a ROC curve by evaluating the slopes of the curve in di

38、fferent regions continuous variable test positive /negative test test that classified into more than two intervals,ETHICAL PRACTICE,Ethical practice can be regarded as appropriate technical practice accompanied b

39、y 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 clini

40、cal services will also apply to the delivery of laboratory services.,Definitions,Why Do We Need Ethics?,ETHICAL PRACTICE,Technically competent service Consultation (select and interpret the tests) Protect the patients’

41、 interestsConfidentiality Medical ethics exist for the protection of patients, and this protection must not be compromised.,Doctor-Patient Relationship,Common Requirements Of Medical Laboratory Ethics,Special Requirem

42、ents 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 incorp