Introductory Concepts

Question 1

Analyte

Answer 1

A substance whose chemical constituents are being indentified and measured

Question 2

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

Plasma Sample

Answer 3

The fluid component of the blood ( comprised of 92-95% water and 5-8% solids) that is harvested after centrifugation of an anticoagulated sample

Question 4

Calcium Binding Agents:

EDTA

Answer 4

Purple top tube

Preferred for routine CBC in mammals

Chelates calcium

Question 5

Calcium Binding agents:

Citrate

Answer 5

Blue top tube

Preferred for coagulation testing

Forms and ionic bond with calcium - adding calcium can override anticoagulant effects

Question 6

Calcium binding agents:

Heparin

Answer 6

Green top tube

Activates antithrombin and forms ionic bond with calcium

Used for dog gas analysis and many chemistry assays

Question 7

Blood Collection Tubes

Answer 7

Always pay attention to what tube is used for each test and be aware of potential problems of using the incorrect tube

Question 8

Hematology Assays

Answer 8

Generally completed on whole blood samples from anticoagulated blood

Complete blood counts, coagulation tests

Question 9

Clinical Chemistry Assays

Answer 9

Completed on serum, plasma, urine, other fluid

Purpose is to detect the concentration of a substance

Question 10

Clinical Chemistry Assays:

Quantitative Analysis

Answer 10

Results are close to true concentrations

Result is a concentration of amount of analyte present

Question 11

Clinical Chemistry Assays:

Semiquantitative Analysis

Answer 11

“Result is approximate or ”in the ball park”

A scale vs. a specific value

Question 12

Clinical Chemistry assays:

Qualitative analysis

Answer 12

Results indicate if a substance is present or not present

Question 13

Clinical microscopy

Answer 13

Study of cell populations and their microscopic features

Question 14

Interpretation of Laboratory data is based on:

Answer 14

An understanding of normal physiologic mechanisms

The ability to recognize the effects of disease on physiologic mechanisms and therefore test results

Question 15

Typical Patient lab work-up

Answer 15

Clinician’s job is to distill test results into useful information that fits with the clinical presentation and history

Diagnose health or disease

Requires and understanding of:

1. reference intervals
2. Analytical properties of assays
3. Role of Quality Assurance and Quality control
4. Knowledge of factors that may cause error
5. A skilled approach at interpretation of the data

Question 16

Reference Intervals:

What are they?

Where do they come from?

Answer 16

The set of values for a physiologic measurement in a healthy individual

It is a basis for comparison to interpret a set of test restuls for a particular patient

Values encompassing median 95% of the populaiton (+/- 2 standard deviations of the mean)