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foundation of practice > concepts of clinical testing > Flashcards

concepts of clinical testing Flashcards

1
Q

patient management uses:

A

Medical examination
* Clinical history
– Presentingcomplaint – Pastmedicalhistory
* Physical examination
* Differential diagnosis
* Investigations
– Laboratoryand/orRadiology
* Diagnosis
* Treatment
– SurgeryorMedical
* Monitor outcome
– Diseaseandtreatment

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2
Q

labprtary investgiations uses:

A
  • Clinical Biochemistry
  • including endocrinology and
    metabolism
  • Clinical Microbiology
  • Haematology
  • Immunology
  • Medical Genetics
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3
Q
  • the use of biochemical technique in the study of molular basis of disease and in diagnosis and management
  • the aim is to provide an answer to a question posted about a patient
    is ——-
A

clinical biochemistry

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4
Q

the process of the clinical biochemistry:
1- selection of appropriate —-
2- measuring of analytes in —-
3- interpetation of —-

A
  • investigation
  • body fluids
  • results
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5
Q

the 3 phases includes:
1-pre analytical: —–
2- analytical : ——
3- post analytical : —

A

1-Appropriate investigation & sample collection
2-
* Method selection
* Quality control & uncertainty of measurement
3- interpretation of results

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6
Q

—- is the use of appropriate investigation and sample collection
-sample examples include:

A
  • pre analytical
    • Blood
      Whole blood
      Plasma
      Serum - Urine
      Spot urine sample
      24-hour urine collection
  • Cerebrospinal fluid
  • Sweat
  • Faeces
  • Sputum & saliva
  • Tissue & cells
  • Aspirates e.g. joint (synovial) fluid
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7
Q

1-pre analytical phase needs patient — such as:
2- the blood sample type such as:

A

1- patient preparation such as:
note of:
* Age of patient - Adult or child
* Time of day- Morning, afternoon or nighttime
* Fasting or post-prandial
* Exercise
* Medication
* Patient preparation
* Cleanse venepuncture site
2-:
- whole blood: serum clotted sample
- plasma : preservative , lithium heprin , EDTA
- transport of sample to lab: by porter + pneumatic tube transport
- laboratory info system (LIS): data entry
- sample preparation: labelling + centrifugation

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8
Q

analytical methods needs:
and it includes

A
  • needs: method selection and faulty control & uncetentiy of measurements
    in includes:
    1- chromatography : GC or tandem -MS
    2- immunological assays: enzyme linked immunosobenant assay ( ELISA)
    3- spectrophotometric assay
    4- nephelometric : light scatter
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9
Q

—- is used to provide unknown compounds by determining mass and matching to known spectra
it provides:

A

-mass spectrometry
it provides:
* elemental composition of sample
* masses of particles and molecules
* potential chemical structures of molecules by
analyzing the fragments
* Produces spectra of masses from molecules in sample and fragments of the molecules m/z

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10
Q

stages of mass spectrometry:
1- ioniser converts some of the sample into —
2- mass analyser separates ions according to their —-
3- detector records either — or —- when ions passes by or hits surface

A
  • ions
  • mass-to-charge ratio
  • charge induced or current produced
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11
Q

—- is the application of science of enzymes to diagnosis of disease and monitoring of treatment and disease progression
- the measurement of enzyme activity or concentration in blood to:

A
  • clinical enzymology
    1- diagnosis: diagnose disease
    2- complications: determine complications and extent of disease
    3- monitoring: monitor disease progression
    ( check slide 16)
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12
Q

duchnenne musuclualr dystrophy:
- it results in a cycle of – and rapture of — in skeletal muscle
- this results in the release of the myocytes —-
- some of the myocytes cytoplasmic content including CK enzyme is released into —

A
  • growth and rapture of myocytes
  • cellular content
  • blood
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13
Q

CK and the diagnosis of Duchenne muscular dystrophy:
- CK ( creatine kinase ) is an enzyme involved in —-
- presents in large amount in —- and —-found in — due routine turnover of skeletal muscle
- elevated – activity in DMD patient ( can be greater than 10x the reference range )
- elevated plasma CK activity in 75% of —- female carriers

A
  • energy production
  • skeletal and cardiac muscle
  • blood
  • plasma
  • asymptomatic
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14
Q

other reasons of muscle damage includes:

A

Excessive physical exercise
- Marathon runners
- Recent strenuous exercise
Surgery
Skeletal muscle trauma Drug induced

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15
Q

1-in cellular damage - why do we measure enzymes ?
2- disadvantages:

A
  • Relatively easy to measure compared with other proteins Can measure the enzyme product
  • lack of tissue specificity and many enzymes present in more than one tissue
    ( check slide 23)
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16
Q

liver enzymes - plasma enzymes used to assess hepatic function includes :

A
  • AST and ALT - aspartate and alanine aminotransferase
    (formally called transaminases and still abbreviated to AST and ALT respectively)
  • ALP - alkaline phosphatase
  • GGT - g-glutamyl transferase
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17
Q

liver diseases
1- pathological changes :
2- tests for liver disease:

A

1- pathological changes
- liver cell damage: acute hepatitis, chronic hepatitis, toxin action, alcohol abuse
- cholestasis: gallstones, cancer at the head of the pancreas Reduced mass of functioning cells (e.g cirrhosis, terminal hepatic failure) Infiltrative disorders - liver is invaded or replaced by nonhepatic substances such neoplasm or amyloid.
2- tests for liver diseases:
-Liver cell damage - enzymes - ALT, AST
-Synthetic function - prothrombin time, albumin
-Conjugating capacity - conjugated bilirubin
-Cholestasis - enzymes - Alk phos, γ-GT (also serum bilirubin)

18
Q

hepatoceullar damage:
— is more liver specific than — however both enzymes are widely distributed in the body tissue but — is present only in small amounts in liver
— has cytoplasmic and mitochondrial iosoenzymes which tends to be released more than — in chronic hepatocellular disease

A
  • ALT
  • AST
  • AST
  • ALT
19
Q

— is known as the failure of normal amounts of bile to reach the intestine
causes:

A
  • cholestasis
  • mechanical block (gallstone, tumour); liver disease; drug induced, e.g. phenobarbitol
    more info : Alkaline phosphatase (ALP) and g-glutamyl transferase (g-GT) – normally “anchored” to membranes of hepatocytes, released in only small amounts in hepatocellular damage.
20
Q

in cholestasis , the synthesis of these enzymes is induced and they are made –

A

soluble ( high concentration of bile acids )
- g-GT more liver-specific – ALP also raised in bone disease
-Changes in g-GT and ALP often parallel each other in cholestatic disease

21
Q

alcoholic liver disease
- the abnormalities depend on – of the disease
- the biochemical abnormalities include:

A
  • severity ( as hepatitis acute or chronic , cirrhosis )
  • AST>ALT
    -Raised γ-GT
    -Increased mean cell volume (MCV) -Hyperbilirubinaemia
    -Raised Alkaline Phosphatase
    -Increased prothrombin time (INR) -Hypertriglyceridaemia
    -Decreased K+, PO43-, Mg2+
22
Q

—- are the parameters indicate that liver disease is due to excessive alcohol intake

A

Raised γ-GT
Increased mean cell volume (MCV)

23
Q

-The appearance of a small amount of enzyme in the bloodstream from damaged tissue can be detected with —-
- enzymes must be — and conditions/buffer are important

A

great sensitivity , active

24
Q

measurement of enzymes in blood - the factors affecting enzymes activity:

A
  • Substrate concentration
  • Temperature of reaction
  • pH of buffer
  • Presence of cofactors
  • enzyme activators or inhibitors
  • Urea & related compounds may disrupt hydrogen bonds causing inactivation
25
Q

1—— are multiple forms of an enzyme
2- tissue specific ones is when certain genes may be expressed exclusively in — tissue as:
3- has cellular — within specific organelles as mitochondria and cytoplasm

A

-izoenzymes
- one
-as: LD , CK , alkaline phosphatase
- cellular localisation

26
Q

izoenymes are multiple – of an enzyme that posses the ability to —–
they differ in —-
example:

A
  • multiple forms
  • catalyse enzymes characteristic reaction
  • differ structurally - encoded by district gene
  • example: creatine kinase and lactate dehydrogenase ( check slide 33)
27
Q

— is known as the death of part of the whole heart due to a blockage of an artery

A

mycocardial infraction

28
Q

cardiac biomarkers as —- are —- as they rise and then slowly fall over a period of time after an —

A
  • CK-MB or troponin
  • temporal
  • infraction
29
Q

measuring CK isotype levels:

A
  • The different isotypes have different electrophoretic mobility.
  • These can be quantified
  • MM and MB forms predominantly
    increased after infarct.
  • The brain isoform is not increased significantly
    ( check table 38)
30
Q

plasma enzyme levels dependant on :

A

Rate of release from damaged cells Rate of damage to cells
Extent of cell damage
In the absence of cell damage, rate of release depends on:
- Rate of cell proliferation (malignancy)
- Degree of induction of enzyme synthesis
Rate of clearance (removal) from circulation

31
Q

why measure enzyme activity in body fluids :

A
  • A small increase in enzyme in the blood from damaged tissues can be detected with great sensitivity
  • Monitor changes in substrate or product concentrations
  • Easier than measuring protein directly as the signal is amplified from the reaction
  • Can measure co-factor changes
  • Enzymes are also antigens can be measured directly - bind to enzyme-specific antibodies
32
Q

immunochemical technique is when – used to detect chemical substance of interest ( antigen )
- depends of – and high – of antibody for specific antigen coupled w ability pf antibody to – w antigen
- allows — and — of specific substance by variety of methods

A
  • antibody
  • sensitivity
  • affinity
  • cross link
  • identification
  • quantification
33
Q

isotopic and non isotopic immunoassay:

A

Method of detection:
-Isotopic: Scintillation
-Non-isotopic: chemiluminescence, fluorescence, photometry
-Safety – hazards, handling & disposal
example:
1-Enzyme Immunoassays
Enzyme-linked Immunosorbent assays
- ELISA
2-Enzyme Multiplied Immunoassay Techniques - EMIT
( check till slide 49 pls)

34
Q

enzyme multiplied immunoassay technique - EMIT:
1- homogenous assay to – drugs , hormones , and metabolites ( antigens )
2- patient sample added to a — containing —- and —
3- antibody – enzyme activity when no drug present
4- if there’s is a drug in the patient sample , this competes for the —
5- this — the enzyme site allowing the – to occur

A
  • analzye
  • tube
  • labelled enzyme and antibody
  • antibody
  • opens
  • reaction
35
Q

In EMIT:
* No —— required- patient sample mixed with reagents
* The more drugs/hormone in the patient sample
* The more drug — to antibody (competing with bound Ab)
* The more enzyme is available for converting the substrate to the product
* A standard curve is used —- the amount in the sample

A
  • seperation
  • binds
  • quantify
36
Q

— is the interpretation of results and it includes :

A
  • post analytical phase
  • includes:
    Validation of results
    Review of internal and external quality assurance results
    Internal – precision External - accuracy
37
Q

interpretation of results :

A

1-Results are often reported as concentrations:
Concentrations change when:
-Amount of the analyte changes
-Volume of solution changes e.g. with dilution
(Beware differing units e.g. molarity vs. μg/ml)
2-Variability of results caused by:
-Analytical factors and Biological factors
3-Uncertainty of Measurement
- Estimates the difference between measured value and true value -
-describes a level of confidence in the measurement
4-Factors affecting uncertainty
- Sample collection and transport
- Calibration, precision and bias of assay
5-Reporting uncertainty of measurement
Plasma Sodium 141 mmol/L +/-0.64 mmol/L
( CHECK SLIDES FROM 52 PLSSS)

38
Q

—– the range of values that represent 90 or 95% of reference population

A

reference range ( check slide 57)

39
Q

Plasma alkaline phosphatase (total) activity Isoenzymes present in plasma derived from:-

A

Bone Liver Kidney Placenta
3rd trimester of pregnancy Intestine
following fatty meal ( check slide from 59)

40
Q
  • selection of enzymes for diagnosis or prognostic purposes depends on:
A

1-Distribution of enzyme among various tissues
-Tissue / plasma concentration gradient
-intracellular localisation
2-Convenience of enzyme assay
-Knowledge of plasma enzyme characteristics
-Half-life in blood
-Mode of clearance

41
Q

why do we need to know all this - the lab results and reference ranges are affected by — such as:

A
  • labarotary methodology as:
    1- substrate and substrae concnetration
    2- buffer and pH
    3- temp
    5- presence of enzyme activator/inhibitor ( check slide 63 -62)

foundation of practice (59 decks)

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