Overview of the Laboratory Analytical Process

Question 1

How many medical decisions are based on laboratory results?

Answer 1

75-80%

Question 2

What is the most common fluid submitted for analysis?

Answer 2

Blood

Question 3

What is the 2nd most common fluid submitted?

Answer 3

urine

Question 4

What are qualitative tests? How are results reported?

Answer 4

generally “screening” procedures. Reported as positive or negative. Ex: pregnancy test

Question 5

What are quantitative tests? How are results reported

Answer 5

measures the amount of substance present. Reported in units of measure. Methods tend to be more technically demanding. Ex: Cholesterol level

Question 6

What is semi-quanitative testing?

Answer 6

Not as accurate as quantitative testing, but can provide an indication of approximate concentration of a substance. Ex. UA reagent strip: glucose, protein, blood, etc

Question 7

What do screening tests determine?

Answer 7

The presence or absence of a disease or condition.

Question 8

Are screening test qualitative or quantitative?

Answer 8

They can be both.

Question 9

What are confirmatory tests?

Answer 9

confirms the accuracy of a screening test by ruling out false pos or false neg results. Uses a different methodology than a screening test.

Question 10

Screening tests require…

Answer 10

a high SENSITIVITY to eliminate FALSE NEG

Question 11

Confirmatory tests require…

Answer 11

a high SPECIFICITY to eliminate FALSE POS

Question 12

How to labs define a test as abnormal or normal?

Answer 12

They use a reference range.

Question 13

How are references ranges determined?

Answer 13

by each laboratory (institution).

Question 14

How are reference ranges established?

Answer 14

performing tests on groups of healthy people to determine expected results for a healthy population. Should reflect a GAUSSIAN distribution.

Question 15

How is the reference range statistically calculated?

Answer 15

The mean, +/- two standard deviations. They should include about 95% of values from the healthy individuals tested.

Question 16

A value that falls outside of the reference range is called?

Answer 16

Abnormal and suggests the presence of disease

Question 17

What is a value “just below” or “just above” the range is called?

Answer 17

Gray zone. Basically, what is normal for one person may be abnormal for another. Healthy person may have abnormal value. Individual who is not healthy may have normal results.

Question 18

What are the three phase of the testing process?

Answer 18

pre-analytical, analytical, post-analytical.

Question 19

Describe the Pre-analytical phase

Answer 19

includes all aspects of specimen procurement that could affect the integrity of the test sample

Question 20

What aspects of the pre-analytical phase could be affected?

Answer 20

ordering correct test, patient prep, specimen collection, transport to lab, processing of specimen before analysis.

Question 21

What is the analytical phase?

Answer 21

encompasses the actual testing process.

Question 22

What aspects of the analytical phase could be affected?

Answer 22

reagents, type of water used, instruments, type of glassware, individual technique, do the test results make sense?

Question 23

What is the post-analytical phase?

Answer 23

Reporting lab data to healthcare provider

Question 24

What aspects of the post analytical phase could be affected?

Answer 24

recording or reporting tests, calculation of results, critical patient values, do patient values correlate with previous results?

Question 25

What should the final test results reflect?

Answer 25

all the factors encountered during all phases of the analytical process

Question 26

What are the most common source of invalid test results and the most diffucult to account for?

Answer 26

pre-anaylitcal phase mistakes

Question 27

How does the lab try to reduce errors?

Answer 27

protocols, written instructions for patient and health care providers.

Question 28

What is quality assurance?

Answer 28

the lab must provide accurate and precise testing results. QA procedures are used to control factors that could affect patients results.

Question 29

What does quality assurance consist of?

Answer 29

Written policy and documented actions

Question 30

What written lab procedures must be followed?

Answer 30

Clinical and Laboratory Standards Institute format. (see slide 28 and 29 for examples)