Day 1

Question 1

When considering a lab test, what are some things you should take into consideration before you order it?

Answer 1

1. Is the test just information or diagnostic
2. If 2 tests give you the same information, when should one be used before another?
3. What are disadvantages and possibilities of errors or false results

Question 2

What do unnessisary tests do?

Answer 2

• Hurt patient financially
• Can be inconvenient
• Wasted or misleading information
• Loss of time

Question 3

What are multichannel chemical analyzers?

Answer 3

Take a large number of tests and have the results back in a short time
-Came back that this wasn’t very helpful for diagnosing disease in asymptomatic patients

Question 4

Tests should be ordered to _______

Answer 4

• Confirm a diagnosis based on the entire clinical picture (history and clinical presentation)
• Or if the result will alter therapy decisions

Question 5

This is the ability of a test to detect patients with a specific disease

Answer 5

Sensitivity

Question 6

T/F- False negatives are found in sensitive test

Answer 6

True

Question 7

What does a test that has 90% sensitivity mean?

Answer 7

That in 10% of patients with the disease, the test will not detect it

Question 8

This describes how well the test abnormality is restricted to those patients that have the disease in question (that it picks up on the sign due to that specific disease)

Answer 8

Specificity

Question 9

Specific tests sometimes show….

Answer 9

False Positives

Question 10

Describe false positives…

Answer 10

A specificity of 90% for disease X indicates that 10% of the test results suggestive of disease X aren’t due to disease X

Question 11

This is the incidence of disease (number of people with the disease) in the population being tested

Answer 11

Prevalence

Question 12

Describe predictive value

Answer 12

The smaller the number of people with a disease, the lower the proportion of people with an abnormal test, and the greater the proportion of false positives

Question 13

If you wouldn’t believe a test, it has a high/low predictive value

Answer 13

Low

Question 14

How is predictive value applied to lab test?

Answer 14

Predictive value evaluates the reliability of a positive or negative result

Question 15

What 2 things are used to establish predictive value?

Answer 15

The sensitivity and specificity of the test in question

Question 16

T/F- To establish predictive value you need a reference method for diagnosis to be available other than the test being evaluated?

Answer 16

True

Question 17

This is what the test in question is compared to

-The best test

Answer 17

Gold Standard

Question 18

If it is not possible to detect patients with a certain disease…

Answer 18

Its not possible to provide a truly accurate calculation of sensitivity, specificity, and predictive value

Question 19

Reliability of laboratory tests is affected by…

Answer 19

Technical performance in the lab

Question 20

The measure of how closely the lab can approach the same answer when the test is repeatedly performed with the same sample

Answer 20

Reproducibility

Question 21

What factors influence reproducibility

Answer 21

• Experience of technicians
• reagents involved
• equipment used

Question 22

How is variation of the mean expressed?

Answer 22

Standard deviation

Question 23

When the standard deviation is converted to a percentage of the mean value, this is called?

Answer 23

Coefficient of variation

Question 24

The higher the coefficient of variation, the higher/lower the accuracy, greater/lesser reproducibility?

Answer 24

Lower accuracy, lesser reproducibility

Question 25

Reproducibility is demonstrated with the coefficient of variation of ___ %?

Answer 25

4%

Question 26

What does the coefficient of 4% mean?

Answer 26

That 68% of values are within 1 standard deviation (4% above and 4% below the true value)

Question 27

+/- ___ standard deviations is used to define acceptable limits?

Answer 27

2

Question 28

A deviation of ___% is deemed technically acceptable

Answer 28

8%

Question 29

This is the correct answer, and the result that the assay should produce

Answer 29

Accuracy

Question 30

How does the lab figure out the accuracy of a test?

Answer 30

Compare it to the assay

Question 31

What happens in a random inaccuracy?

Answer 31

-Random inaccuracies may not effect all of the specimens and therefore may have not altered the control specimens

Question 32

What are examples of random inaccuracies?

Answer 32

- Specimen from the wrong patient - Specimen hemolysis - Insufficient mixing - Clerical errors (patients with the same last name) - Decimal point errors - Transcription of results into the wrong charts

Question 33

If unexpected test results are seen, what should you do first?

Answer 33

Repeat the tests

Question 34

T/F- Normal range is a concept that considers all tests within the normal range to be normal and anything outside the normal range to be abnormal

Answer 34

True

Question 35

What are the 2 premises involved in establishing the normal range?

Answer 35

1. Assume that all patients do not demonstrate clinical signs and symptoms that are normal 2. Assume that test results from those people considered normal will have random distribution

Question 36

Are any factors that would bias a significant group toward either the high or low side included?

Answer 36

Nope!

Question 37

What percentage of values fall in +/- 1 standard deviation?

Answer 37

68%

Question 38

What percentage of values fall within +/- 2 standard deviations?

Answer 38

95%

Question 39

What percentage of values fall within +/- 3 standard deviations?

Answer 39

99.7%

Question 40

If 2 standard deviations are accepted, what percentage of clinically normal people will have values above and below this range?

Answer 40

2.5% above and 2.5% below

Question 41

What if clinically normal people have undetected disease?

Answer 41

They will influence the normal range so... -you have to take the top values or the lowest values and run their labs again using the gold standard tests to see if they are in fact normal- if not, they are outta hereee and you made your normal range more accurate

Question 42

What factors may effect results in non-diseased patients?

Answer 42

- Age - Sex - Race - Diet - Posture - Specimen storage time

Question 43

The greater number of tests employed, the greater/lesser the chance that at least one will yield a false result?

Answer 43

Greater

Question 44

The farther away the values are from the normal limits, the greater/lesser the likelihood of a true disease

Answer 44

Greater

Question 45

Instead of the word normal, use the word...

Answer 45

Reference range