Ch?: Lab Testing Flashcards
1
Q
What is mean?
A
Average value of a series of values.
2
Q
What is median?
A
The middle number of a set of values.
3
Q
What is mode?
A
Most frequent value of a set of data.
4
Q
What is standard deviation?
A
Analysis of how tightly values are distributed around the mean.
5
Q
Two standard deviations encompass what percentage of values?
A
95.5%
6
Q
What is the coefficient of variation?
A
Standard deviation as a percentage of the mean
7
Q
The smaller the CV, is the test more precise or less precise?
A
More precise
8
Q
A low CV assay has a narrow or wide distribution curve?
A
Narrow
9
Q
A high CV assay has a narrow or wide distribution curve?
A
Wide
10
Q
What is the standard deviation index?
A
The difference in terms of the number of standard deviations from the overall mean.
11
Q
What is SDI used to determine?
A
Difference between your test results and the overall average of all participating labs.
12
Q
What is a good SDI value?
A
Plus or minus 1
13
Q
What is the borderline SDI value?
A
Plus or minus 1-2
14
Q
What is a bad SDI value?
A
Plus or minus 2+
15
Q
If all of your tests run all positive in terms of SDI’s, what does this suggest?
A
Your method is on the high side and you have a positive bias.
16
Q
What is the sensitivity of a lab test?
A
Capacity of a test to identify all individuals with disease.
17
Q
Increasing sensitivity of a test may increase what?
A
False positive test results
18
Q
Sensitivity only uses values of what patient populations?
A
Patients with disease
19
Q
What is specificity of a lab test?
A
Capability of a test to identify all individuals without disease
20
Q
Increasing specifity of a test may increase what?
A
Number of false negative results
21
Q
Specificity is only used with what population of patients?
A
Patients without disease
22
Q
What is the positive predictive value?
A
Probability that a positive test result represents disease in an individual.
23
Q
PPV only uses what for data?
A
Those with positive test results (true positives and false positives)
24
Q
NPV represents what?
A
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
