Laboratory Test Interpretation

Question 1

what is the difference between serum and plasma?

Answer 1

plasma = anti-coagulated blood
serum = clotted blood (no anticoagulant)

Question 2

sensitivity of a test

Answer 2

the frequency with which a test is positive in patients that have the disease of interest

Question 3

specificity of a test

Answer 3

the frequency with which a test is negative in patients that do not have the disease of interest

Question 4

positive predictive value

Answer 4

the probability that subjects with a positive screening test truly have the disease

Question 5

negative predictive value

Answer 5

the probability that subjects with a negative screening test truly don’t have the disease

Question 6

What affects predictive values?

Answer 6

Sensitivity, specificity and prevalence of the disease.

Question 7

A test that has high sensitivity is good for…

Answer 7

screening (very few false negatives)

Question 8

A test that has high specificity is good for…

Answer 8

confirming that an animal has a disease – because it has very few false positive results.