General info

Question 1

What is the reference range?

Answer 1

Normal ranges for a test

Question 2

The normal reference range include how many standard deviations and what percentage of the population?

Answer 2

2 standard deviations
central 95%.
Individuals may be outside of this range but still not have the disease

Question 3

What is the therapeutic range

Answer 3

Range for certain medications to provide a target therapeutic effect or drug level. Outside of this range may cause toxicity or therapeutic failure

Question 4

Name some tests that don’t have a range

Answer 4

Pregnancy test, cardiac enzymes, drug abuse

Question 5

Define sensitivity and give the formula

Answer 5

Capacity to identify all individuals with the disease

true+ / (true+ + false-) x 100%

Question 6

Define specificity and give the formula

Answer 6

Effectiveness of a test to correctly identify those without disease
true- / (true- + false+) x 100%

Question 7

What is prevalence

Answer 7

the number of existing cases in a population and is expressed as a percentage of the population

Question 8

What is incidence

Answer 8

the number of new cases occurring with a period of time, usually 1 year

Question 9

Define positive predictive value and give the formula

Answer 9

the likelihood that a positive test result identifies someone with the disease
true+ / (True+ + false+) x 100%
Influenced by the prevalence of the disease.

Question 10

Define Negative predictive value and give the formula

Answer 10

the likelihood that a negative test result identifies someone without the disease
true- / (true- + false-) x 100%
Not influenced by prevalence of the disease

Question 11

Define precision

Answer 11

the ability to test one sample and repeatedly obtain results that are close to each other

Question 12

Define Accuracy

Answer 12

the relationship between the number obtained and the true result

Question 13

Examples of pre-analytical errors - most common place for errors

Answer 13

in appropriate preparation of the patient
not fasting
ingesting drugs that interfere with the test
collection of specimen in the wrong tube
delayed transport to the lab
inappropriate storage of the sample
collection of inadequate amount of blood

Question 14

Examples of analytical phase errors

Answer 14

Incorrect use of instrumentation

Use of expired reagents

Question 15

Examples of post-analytical phase errors - second most common place for errors

Answer 15

Delay in time to enter a completed result

Reporting results to the wrong patient

Question 16

Reasons for obtaining lab tests

Answer 16

To establish or exclude a diagnosis
To rule out a clinical problem
To screen for a disease
To monitor therapy
To evaluate severity of a disease
To monitor the course of a disease
To detect disease reoccurence
To determine effective drug dossage and to prevent toxicity

Question 17

What is plasma

Answer 17

blood - (WBCs, RBCS, platelets)

contains dissolved proteins, hormones, CO2, clotting factors, electrolytes, gluose

Question 18

What is serum

Answer 18

blood - (WBCs, RBCs, platelets, fibrinogen, prothrombin)

plasma with clotting factors removed.