Lab Testing Normals/Abnormals

Question 1

what are 5 indications for lab testing

Answer 1

1. screen for disease in apparently healthy individuals
2. assess the presence and severity of disease in sick animals
3. resolve between differential diagnosis
4. develop a prognosis
5. evaluate response to therapy

Question 2

what does a high rate of false negative mean in terms of specificity/sensitivity

Answer 2

low sensitivity

Question 3

what does a high rate of false positive mean in terms of specificity/sensitivity

Answer 3

low specificity

Question 4

can a diagnosis be made or ruled out based on a single test

Answer 4

NO - must be panels, multiple tests, history, physical exam, and other diagnostics

Question 5

what are reference intervals based off of

Answer 5

healthy adult population
- minimum sample size of 40
- recommend sample size >120

species specific

Question 6

for a given test, approximately how many healthy patients will have an abnormal value

Answer 6

5%

Question 7

predictive values

Answer 7

the probability of a disease being present in a patient with an abnormal test result, or absent with a normal test result

depends on:
1. sensitivity
2. specificity
3. disease prevalence

Question 8

positive predictive value

Answer 8

the % probability that a positive test result is a true positive

increases with prevalence
impacted by specificity

Question 9

negative predictive value

Answer 9

the % probability that a negative test result is a true negative

decreases with prevalence
impacted by sensitivity