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Flashcards in Ch?: Lab Testing Deck (111):
1

What is mean?

Average value of a series of values.

2

What is median?

The middle number of a set of values.

3

What is mode?

Most frequent value of a set of data.

4

What is standard deviation?

Analysis of how tightly values are distributed around the mean.

5

Two standard deviations encompass what percentage of values?

95.5%

6

What is the coefficient of variation?

Standard deviation as a percentage of the mean

7

The smaller the CV, is the test more precise or less precise?

More precise

8

A low CV assay has a narrow or wide distribution curve?

Narrow

9

A high CV assay has a narrow or wide distribution curve?

Wide

10

What is the standard deviation index?

The difference in terms of the number of standard deviations from the overall mean.

11

What is SDI used to determine?

Difference between your test results and the overall average of all participating labs.

12

What is a good SDI value?

Plus or minus 1

13

What is the borderline SDI value?

Plus or minus 1-2

14

What is a bad SDI value?

Plus or minus 2+

15

If all of your tests run all positive in terms of SDI's, what does this suggest?

Your method is on the high side and you have a positive bias.

16

What is the sensitivity of a lab test?

Capacity of a test to identify all individuals with disease.

17

Increasing sensitivity of a test may increase what?

False positive test results

18

Sensitivity only uses values of what patient populations?

Patients with disease

19

What is specificity of a lab test?

Capability of a test to identify all individuals without disease

20

Increasing specifity of a test may increase what?

Number of false negative results

21

Specificity is only used with what population of patients?

Patients without disease

22

What is the positive predictive value?

Probability that a positive test result represents disease in an individual.

23

PPV only uses what for data?

Those with positive test results (true positives and false positives)

24

NPV represents what?

Probability that a negative test result represents absence of disease in an indvidiual

25

NPV only uses what for data?

Negative results (true negative and false negative)

26

What is accuracy?

Ability of a testing method to give the right or correct result

27

What is precision?

Ability of a testing method to give the same result time after time, whether or not the result is accurate or not.

28

What is the most common method for determining normal ranges?

Reference group method

29

Describe reference group method.

Samples are collected from a normal, random group of healthy individuals and a test value for each individual is obtained. You then determine the value of ranges within 2 standard deviations.

30

What is prognosis/treatment-derived normal range?

Use recommendations based on research and clinical experience to establish desired values.

31

Prognosis/treatment-derived range include what tests? 2

Cholesterol
Hypertension

32

When are threshold values used for normal ranges? (3)

Cardiac markers CK-MB, cTnI, and cTnT

33

Cardiac injury is presumed when what happens?

The threshold values are exceeded.

34

Is a Gaussian curve useful in threshold values?

No

35

What is the therapeutic drug reference range?

Therapeutic window for therapeutic drug levels.

36

What establishes the therapeutic drug reference range?

Experimentation and clinical data to maximize the drug's therapeutic effects while minimizing the drug's toxic effects.

37

What is comparison of previous test results and how is it used for determining normal range?

Patient's previous test results are used as a basis to determine presence of disease or change in disease status.

38

Comparison of previous test results in used with what markers?

PSA, CEA, and CBC

39

What were once the work horses of medical laboratories?

Spectrophotometric or colorimetric assays

40

What are the steps of a spectrophotometric assay? 3

1. Take patient's serum and add a sample to the assay.
2. Add a couple of reagents
3. Observe for color change

41

What does nephelometry look for?

Cloudiness of a sample

42

What are the steps of nephelometry? 3

1. Antigen of interest in a patient's specimen is added
2. Monoclonal antibodies against antigen are added
3. Scattered light is measured.

43

What does it mean if nephelometry results in high level of scattered light?

High level of antigen

44

What are steps of enzyme immunoassay (ELISA)? 3

1. Patient's serum with antibodies is added to ligand coated well
2. Enzyme conjugated anti human Ab's are added which bind to the sample Ab's.
3. Enzymes form a substrate which can be measured by amount of light scattering

45

What is ELISA sandwich immunoassay? 3

1. Sample antigen added to antibody coated well.
2. Enzyme conjugated Ab's added and bind to antigen.
3. Enzymes form a substrate which can be measured by amount of light scattering

46

Latex agglutination has what steps?

1. Specimen from a patient is applied.
2. Latex particles w/ Ab's against antigen are added
3. Patient specimen and latex reagent are mixed.
4. You can see based on agglutination if the antigen is present

47

What are the steps of forward typing ABO/Rh? 3

1. Patient's RBC's mixed with antisera of (anti-A, anti-B, and anti-Rh)
2. Tubes are gently mixed
3. Specimens are centrifuged and examined for agglutination.

48

What are the steps of reverse typing ABO/Rh? 3

1. Patient's serum mixed with reagent RBC's (A cells and B cells)
2. Tubes are gently mixed
3. Specimens are centrifuged and examined for agglutination.

49

What are steps of the direct antiglobulin test? 2

1. Patient's RBC's combined with antiglobulin reagents (anti-IgG/anti-C3d first, then anti-IgG, anti-C3d)
2. Centrifuge and examine for agglutination or hemolysis

50

Direct and indirect antiglobulin tests are looking for what?

Antibodies in the serum

51

Steps of indirect antiglobulin test? 5

1. Patient's serum is combined with reagent cells)
2. Centrifuge
3. 30 min incubation
4. Anti-human globulin reagent added
5. Examine for agglutination or hemolysis

52

Direct immunofluorescence involves what players?

Fluoresecent labeled antibody against the antigen of interest.

53

Indirect immunofluorescence involves what players?

Antibody against the antigen of interest

54

What are the steps of antinuclear antibody testing? 4

1. Patient's serum is added to hEP-2cell
2. If antibodies are present they bind
3. Anti-IgG fluorescent labeled antibodies are added.
4. Look under microscope for presence of anti Ab's

55

For SLE, what will the antinuclear antibody test show?

95-98% of patients with active SLE have positive results.

56

For, SLE, CBC is useful to determine what?

If disorder is associated with WBC's or platelets and if cytopenia has been initiated

57

Which autoantibodies are SLE really known for? (2)

1. dsDNA
2. Sm

58

For, SLE, Bun/Creatinine are used for what?

See if SLE medications have affected renal function

59

Histone auto-antibodies are seen in what subset of SLE patients?

Drug-induced SLE (95%)

60

What antibodies are looked for in Sjogren syndrome? 2

anti-SS-A (Ro)
anti-SS-B (La)

61

What antibodies are looked for in polymyositis and adult dermatomyositis?

Anti-Jo-1

62

What antibodies are looked for in mixed connective tissue disease?

Anti-U1 RNP

63

What antibodies are looked for in scleroderma?

Anti-Scl-70 (topoisomerase I)

64

What is diagnostic of limited scleroderma?
What is this disease called?

Centromere Ab's showing up on ANA.
CREST syndrome

65

What does CREST syndrome stand for?

1. Calcinosis
2. Raynaud's
3. Esophageal dysmotility
4. Sclerodactyl
5. Telangectasia

66

Explain the steps of Blood gas measurements for pH? 4

1 Arterial blood put on ice
2. Sample put into an analyzer for pH,
3. Hydrogen ions permeate through a membrane
4. Potential created between the reference and internal electrode is measured

67

Explain the steps of Blood gas measurements for pCO2?.4

1. Arterial blood put on ice
2. Sample put into an analyzer for pCO2
3. CO2 permeates into a buffered solution of sodium bicarbonate
4. Generated hydrogen is measured in a pH electrode

68

Explain the steps of blood gas measurements for pO2? 4

1. Arterial blood put on ice
2. Sample put into an analyzer for pO2
3. O2 from sample is reduced on a platinum electrode
4. Generated current is measured

69

PT evaluates what pathway?
what therapy is used here?

Extrinsic
Coumadin

70

PTT evaluates what pathway?
What therapy is used here?

Intrinsic
Heparin

71

Explain steps of coagulation assay PT?

1. Patient plasma is placed in curvette
2. initiate clotting by adding thromboplastin + calcium
3. Forming clot increases absorbance of specimen
4. Time it takes for clot to form is the PT

72

Explain steps of coagulation assay PTT?

1. Patient plasma is placed in curvette
2. initiate clotting by adding partial thromboplastin + calcium and activator
3. Forming clot increases absorbance of specimen
4. PTT is time is takes for formation of clot

73

PT assay looks at what factors?

II, V, VII, X

74

PTT assay looks at what factors?

VIII, IX, XI, XIII

75

Genetic bleeding disorders that prolong coagulation tests include what example?

Hemophilia

76

Acquired bleeding disorders that prlong coagulation tests include what?

Vitamin K deficiency

77

Genetic disorders that may cause thromboses include what example?

Factor V Leiden

78

Acquired disorders that may cause thromboses include what example?

Anti-cardiolipin Ab's

79

The sed rate (ESR) is an indication of what?

Inflammation

80

The higher the sedimentation rate what does it mean?

Greater the inflammation

81

What has begun to replace sed rate?

CRP

82

What is sed rate still used to diagnose? 3

Temporal arteritis (giant cell)
Subacute endocarditis
Osteomyelitis

83

Describe flow cytometry? 4

1. Cells flow in single cell stream
2. Laser beam is shot at the cells
3. Side scattered light and forward scattered light are both measured
4. Cells are then separated and collected based on size, shape, and composition

84

Side scatter represents what of cells?

Cell granularity

85

Forward scatter represents what?

Cell volume

86

What are steps for using flow cytometry to determine whether specific cells are present in blood? 3

1. Cell suspension is combined with specific fluorescent labeled antibodies
2. Then run through the cytometry and have laser hit the Ab's
3. Different colored antibodies will present with their color on the results.

87

What are the three things you can determine from an automated blood cell counter?

1. Platelet count
2. RBC count AND mean MCV
3. Flow cyometry and count of identified cell types

88

What does hemogram mean?

Only testing for RBC data (Hgb, Hct, MCV)

89

Red blood count is expressed as what?

___ x 10^6/mm^3

90

Hct is expressed as what?

Fraction of RBC volume to total blood volume

91

Hgb is expressed in what units?

g/dL

92

MCV is expressed as what?

femtoliters

93

MCHC is expressed as what unit?

g/dL

94

RDW is expressed as what?

Percentage that indicates the degree of RBC variation in size and changes in shape

95

RBC variation in size is known as what?

Anisocytosis

96

RBC variation in shape is known as what?

Poikilocytosis

97

The WBC is given in what units?

Number of cells per volume

98

A five part differential of WBC will include what?

1. neutrophils
2. lymphocytes
3. monocytes
4. eosinophils
5. basophils

99

What confirms what a CBC flags as abnormal?

Peripheral blood smear

100

Abnormal Hgb, Hct levels are used to diagnose what?

Anemia and polycythemia

101

Microcytic anemia is classified by what?

MCV less than 80

102

What are the four causes of microcytic anemia?

1. iron deficiency
2. thalassemia
3. Lead toxicity
4. anemia of chronic disease

103

What is useful in testing for thalassemias?

Hemoglobin Electrophoresis

104

Normocytic anemia has what MCV values?

80-100

105

Macrocytic anemia has an MCV of what?

100

106

Causes of normocytic anemia? (4)

Anemia of chronic disease
Anemia of chronic renal disease
Acute blood loss
Primary bone marrow abnormalities

107

Causes of macrocytic anemia? 6

B12 and folate deficiencies
Liver disease
Ethanol use/abuse
Drugs
Hypothyroidism
Myelodysplastic syndromes

108

What is used to test for immunoglobulin in serum, urine, or CSF? 2

Protein electrophoresis
Immunoelectrophoresis
Immunofixation

109

What is used to begin categorizing bacteria?

Gram stain

110

What does a antimicrobial susceptibility tests?

Determine sensitivity or resistance of a microbe to a certain anti-microbial

111

urinalysis is used for what?

Determine presence of WBC's, protein, glucose, ketones, urobilinogen, bilirubin, blood, and pH