Interpreting Test Results

Question 1

Contents of a lab report

Answer 1

Demographic details from request
Results from lab analysis
Reference ranges from scientific knowledge
Comments and advice from experience (both human and computer knowledge bases)

Question 2

The Normal Range vs Reference Range

Answer 2

Normal range is defined values for comparison
However, these are made up and no clear boundaries exist
Reference preferred as a term as it seems more flexible

Question 3

The ideal test

Answer 3

Highly sensitive and specific
Low rate of false positives and false negatives
Very rarely available

Question 4

Strategies to improve tests

Answer 4

Select a more appropriate ‘normal’ population
Use a combination of tests e.g. LFT profiles
Combine tests to achieve a diagnostic goal

Question 5

Appropriate ‘normal’ populations

Answer 5

Patients with similar presenting symptoms
Same age
Same gender
Hospitalised 'normals'
Same underlying disease

Question 6

Factors affecting reference ranges

Answer 6

Age
Gender
Diet
Pregnancy
Time of month
Time of day
Time of year
Weight
Stimulus

Question 7

Action limits

Answer 7

For cholesterol and paracetamol

Limits before action needs to be taken

Question 8

Therapeutic ranges

Answer 8

For drugs

Lithium and digoxin