General pathology

Question 1

What are inter individual factors? Give some examples

Answer 1

Inherent differences between groups of animal due to effects of species, breed, age and sex

• Cats PCV< dog’s
• Akitas have lower mean cell volumes
• Growing dogs have lower PCV/ total protein conc than adults
• Males have high PCV values

Question 2

What are intra-individual factors?

Answer 2

• Transient differences in the same animal due to usually external/ environmental factors e.g. fasting/ diet/ excitement/ reproductive status/ drugs
• Can results in outlier results when compared to normal ranges

Question 3

Give examples of intra individual factors

Answer 3

• A recently eaten meal or certain diet with increase blood glucose, lipids and bile acids in monogastrics
• Adrenergic response will increase PCV in horses or glucose in cats
• Lactation will result in decreased serum Calcium
• Drug therapy e.g. glucocorticoids will increase ALP/ ALT in dogs

Question 4

What are pre instrumental factors?

Answer 4

• Poor blood sampling e.g haemolysed from you pumping syringe when taking sample

Question 5

What are the advantages and disadvantages of serum?

Answer 5

• Advantages: most ‘normal values’ are given in serum conc and autoanalysers may work better for serum than plasma
• Cons: can’t look at cells, you have to ass an anticoagulant that can be removed. Separation requires time for clot to form and separation is more like to cause haemolysis.

Question 6

What would you put in a lithium hep tube?

Answer 6

Plasma

Question 7

Describe the storage/ transportation of samples

Answer 7

• Plasma/ serum must be separated quickly as some compounds aren’t stable in whole blood and red cell can haemolyse.
• Sample should be kept in closed tubes, cool and dark
• If frozen serm -20 and plasma -70

Question 8

Name an anticoagulant used in haemoaatology

Answer 8

EDTA- doesn’t affect cell size so is good when wanting to perform a cell count

Question 9

Name anticoagulants used in clinical chemistry

Answer 9

Lithium heparin

EDTA plasma

Question 10

Name an anti coagulant used for glucose tests

Answer 10

Flouride oxalate

Question 11

Name an anticoagulant used in haemostasis or coagulation

Answer 11

Citrate

Question 12

What would happen if you put wanted to measure potassium and ionised calcium levels in a sample with K-EDTA anticoag?

Answer 12

Would have severely erroneous results (high K and low Ca)

Question 13

What is the appearance of an icterc blood sample?

Answer 13

Yellowy due to high bilirubin

Question 14

What is the colour interference effect of haemolysis?

Answer 14

Bilirubin is falsely increased due to similar absorbance range to haemoglobin

Question 15

What is falsely incrase in a haemolysed sample for horses?

Answer 15

Potassium

Question 16

What changes occur in a lipaemic sample?

Answer 16

-Increase in total lipid/ TGs and cholesterol

Question 17

Which controls should be put in place to help reduce variation in results for instrumental factors?

Answer 17

• Validation of techniques used

- Quality control

Question 18

What does P.A.S.S mean?

Answer 18

Precision (repeatability/ reproducibility)
Accuracy (measuring the right thing correctly)
Specificity (analytical)
Sensitivity

Question 19

How do you calculate the coefficient of variation?

Answer 19

standard deviation/ mean

normally given as a %

Question 20

What does Ascorbate interfere with?

Answer 20

-The glucose oxidase reaction of urine test strips

Question 21

What is the analytical range?

Answer 21

The range of values between which a measurement of the concentration of the analyte is possible with a known imprecision. Usually calculated with a series of serial dilution samples.

Question 22

What are the post instrumental factors?

Answer 22

• Validation of the results (clinical interpretation of the result with a high degree of confidence)
• Transfer of the result to the final user
• Archiving the result