Introductory Concepts

Question 1

What is an ‘Analyte’?

Answer 1

A substance whose chemical constituents are being identified/measured

Question 2

What is a serum sample?

Answer 2

• The fluid component of blood that is harvested after centrifugation of a Clotted Sample
  
  • Serum is NOT an in vivo product

Question 3

What is a plasma sample?

Answer 3

• The fluid component of the blood that is harvested after centrifugation of an anticoagulated sample
  
  • Comprised of 92-95% protein and 5-8% solids

Question 4

What are the calcium binding anticoagulants?

Answer 4

• EDTA:
  
  • purple top
  • Preffered for routine CBCs in mammals
  • Chelates calcium
• Citrate:
  
  • Blue top
  • Preferred for coagulation testing
  • Forms an ionic bone with calcium
    
    • adding calcium can override anticoagulant effects
• Heparin:
  
  • Green top
  • Activates antithrombin and forms ionic bond with calcium
  • Used for blood gas analysis and many chemistry assays

Question 5

What is a Hematology assay?

Answer 5

• Generally completed on whole blood samples from anticoagulated blood
  
  • Ex: CBC, Coagulation testing

Question 6

What are Clinical Chemistry assays?

Answer 6

• Completed on serum, plasma, urine, other fluid
• Purpose is to detect the concentration of a substance (the analyte)
  
  • Quantitative - result in close to true concentrations
  • Semiquantitative - result is approximate
    
    • scale (eg +1, +2, …) vs a specific value
  • Qualitative - indicate if a substance is present or not

Question 7

What is Clinical microscopy?

Answer 7

• Study of cell populations and their microscopic features

Question 8

What is interpretation of laboratory data based on?

Answer 8

• An understanding of normal physiologic mechanisms
• The ability to recognize the effects of disease on physiologic mechanisms and therefore test results
• If done correctly - can provide much information about the patient.

Question 9

What are Reference intervals?

Answer 9

• set of values for a physiologic measurement in a healthy individual
• The basis for comparison (a frame of reference) to interpret a set of test results for a particular patient
• Values encompassing median 95% of the population

Question 10

Where do reference intervals come from?

Answer 10

• Must be determined from healthy animals from representative population (different ref int for different regions!)
• Species specific
  
  • 120 health recommened
  • 40 minimum
• Laboratory Specific
• Instrument Specific

Question 11

How is the data from reference intervals interpreted?

Answer 11

• Recognize abnormal values