第十章 共价键与分子间力

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第十章 共价键与分子间力 Powered By Docstoc
					          Chapter 1
General of Clinical Laboratory

            LI Ping
     General of clinical laboratory

Principles to clinical laboratory
The interpretation of laboratory tests
The ethical practice
    Principle to clinical laboratory

     Responsibilities
     Collection of Information
     Collection of Specimens
      (Informed consent 、 Adequate privacy)
     Performance of Test
     Reporting of Result
     Storage and Retention of Medical Records
     Access to Medical Records

 The patient----assurance the quality and integrality of
  the service
 Colleague and professional -----maintain professional
  reputation, aim to contribute the advancement of
 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

Accreditation           Patients
  program               interests

                                    Works with high skill
           Process                   and competence

                      Good performance
                          of tests
                Reporting of Result

 Test results are confidential unless disclosure is

 Report the results correctly and timely

 Provide the consultation about the selection and
  interpretation of 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
  itself as to the identity of the person making the
                                       selection            Biological
   Testing Cycle                                       variability ,improper
                                 Select test             or inconsistent
             Make clinical                         Patients prepare
               decision      Minimize variability    for sampling
                             No confusion and                Improper or
        Check 、report        misunderstanding                 Collection
            result           about test results Collect specimen

Inadequate                                                      Improper
   RVs                                                          provision
                                           Pre-process of
                Analyze specimen
Analytical                                   specimen
                 Biologic variatinon

 Endogenous biorhythms       Different constitutional factors
for physiologic parameters   and lifestyle among subjects

 within-subject variation       subject-to –subject variation

                  Biological variation
                                              Biological rhythms
                  Width of the test’s         factors
                 Referenc interval (RI)       Extrinsic factors

                the diagnostic efficiency
                   of a laboratory test
     Three types of Biological rhythms
             Circadian      Ultradian       Infradian
             Rhythms        Rhythms         Rhythms
Cycle time   24h            <24h            >24h

Character    Consistent     Inconsistent    unknow
             Predictable    Unpredictable
solution     rhythm-        stimulation and unknow
             adjusted RVs   suppression
example      Number and     gonadal         menstrual
             activity of    hormone         cycle
             blood cell
                  Biologic variation

 endogenous biorhythms       Different constitutional factors
for physiologic parameters   and lifestyle among subjects

 within-subject variation       subject-to –subject variation

                  Biological variation
                                              Biological rhythms
                  Width of the test’s         factors
                 Referenc interval (RI)       Extrinsic factors

                the diagnostic efficiency
                   of a laboratory test
      Biologic variabilty ——
                     Constitutional factor
                  rapid physiologic changes
      infants      、hemolysis 、 bilirubin

      children   Plasma protein    enzyme             Age
                 sex hormones                       specific
age                                                reference
      adults      constant until menopause in        limits
                 women and middle age in men

      elderly    age-related differences in
                 nutrition 、intercurrent disease
                  Biologic variabilty –
                  Constitutional factor
Genetic heterogeneity
           Genetic       phenotypic differences

                                       Different reactivity
          Different concentration
                                       towards nucleic acid
          of analyte
                                        probes and antibodies


        Biologic variabilty -
                           Extrinsic Factors
Posture                         homeostasis of             rennin
                                 vascular tone          aldosterone
        supine     stand

                                             plasma volume
   H 2O
Small analyte
                                            Concentration of
                                           nondiffusibl analyte
   vascular      interstitial
    Biologic variabilty –
                       Extrinsic Factors

•   shifts in plasma water
•   glomerular filtration rate
•   urine production
•   release of macromolecules from cells and
   Biologic variabilty -
                       Extrinsic Factors

       meal related                fasting related
            TC                        Lac
           BUN                      Acetone
           GLU                     Glucagons
           ……..                     ……….

 Recommendation : duration of fasting before
  specimen collection is typically 12 hours
   Biologic variabilty –
                      Extrinsic Factors
 Types of Interference ——
     Analytical interference
     Physiologic interference

 Recommendation ——
       Recognize drugs’ potential for occurrence,
  withdraw medications before sampling whenever
      Evaluat any suspicious results in light of a
  subject’s medication history.
   Biologic variabilty-
                       Extrinsic Factors

    plasma volume     hyperventilation

   erythrocyte mass   altered distribution
                       of cardiac output

  plasma protein        endocrinologic
  synthesis                changes
   Biologic variation-summary

 Biological rhythms——
     Circadian , Ultradian ,Infradian rhythms
 Constitutinal factors——
     Gender, age, gene
 Extrinsic factors——
      Posture, Exercise, Diet, Drugs, Pregnancy ,
  Caffeine, Alcohol use, Oral Contraceptives,
  Intercurrent Illness
        Establish and validate RVs
  Establish clinical performance characteristics

           Help clinician to select the most
                 effective tests and testing strategies
Why?       Help clinician to translate laboratory
                results into a probability statement
           Help the laboratory director to focus the
               resources of the laboratory on tests with
               the highest clinical relevance
                             phase II and phase III
How ?      Collect data
                                 clinical trials
          Establish and validate RVs
   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 clinical
   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 Specificity

Disease          Test result          Total
status      Positive       negative
Disease     TP           FN           TP +FN

Healthy     FP          TN            FP +TN

Total       TP +FP      FN+TN         TP+FP
              Sensitivity and Specificity

Sensitivity(Se)=TP/ (TP+FN)
  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
                     Predictive Value

PV+ =TP /(TP+FP )
 The probability that a subject with a positive test result
   truly has the disease
PV- =TN/(TN+FN )
 The probability that a subject with a negative test result
   truly is healthy .

Note PVs are only accurate when the test is applied to
    populations with a disease prevalence that is similar
    to that of the study sample.
                  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
ROC   Curves
                  Likelihood 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
 LHR+ =Se/(1-Sp)               LHR-=(1-Se)/Sp
 =TP rate/FP rate              =FN rate/TN rate

 For continous variable test,LHRs can be established
  for different ranges of test results, so the magnitude
  of a test result provides additional discriminatory
                 Likelihood Ratios

 LHR+ =TP rate/FP rate 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 disease in view of the new
  information contributed by the test result .
                 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 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 appropriate
    technical practice accompanied by integrity in
    attitudes and behavior.
Why Do We Need Ethics?
  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.
                ETHICAL PRACTICE

Doctor-Patient Relationship
 Technically competent service
 Consultation (select and interpret the tests)
 Protect the patients’ interests
 Common Requirements Of Medical Laboratory Ethics
 Confidentiality
 Medical ethics exist for the protection of patients, and
  this protection must not be compromised.

  Special Requirements Of Medical Laboratory Ethics
                  Principles Of Ethics

 Medical Ethics
 Autonomy、Beneficence、Nonmaleficence 、Justice

Ethics In Medical Laboratories
    The ethical standards of those working in medical
    laboratories are derived from medical ethics and
    incorporate the same principles.

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