What are inter individual factors? Give some examples
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
What are intra-individual factors?
- 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
Give examples of intra individual factors
- 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
What are pre instrumental factors?
- Poor blood sampling e.g haemolysed from you pumping syringe when taking sample
What are the advantages and disadvantages of serum?
- 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.
What would you put in a lithium hep tube?
Plasma
Describe the storage/ transportation of samples
- 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
Name an anticoagulant used in haemoaatology
EDTA- doesn’t affect cell size so is good when wanting to perform a cell count
Name anticoagulants used in clinical chemistry
Lithium heparin
EDTA plasma
Name an anti coagulant used for glucose tests
Flouride oxalate
Name an anticoagulant used in haemostasis or coagulation
Citrate
What would happen if you put wanted to measure potassium and ionised calcium levels in a sample with K-EDTA anticoag?
Would have severely erroneous results (high K and low Ca)
What is the appearance of an icterc blood sample?
Yellowy due to high bilirubin
What is the colour interference effect of haemolysis?
Bilirubin is falsely increased due to similar absorbance range to haemoglobin
What is falsely incrase in a haemolysed sample for horses?
Potassium
What changes occur in a lipaemic sample?
-Increase in total lipid/ TGs and cholesterol
Which controls should be put in place to help reduce variation in results for instrumental factors?
- Validation of techniques used
- Quality control
What does P.A.S.S mean?
Precision (repeatability/ reproducibility)
Accuracy (measuring the right thing correctly)
Specificity (analytical)
Sensitivity
How do you calculate the coefficient of variation?
standard deviation/ mean
normally given as a %
What does Ascorbate interfere with?
-The glucose oxidase reaction of urine test strips
What is the analytical range?
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.
What are the post instrumental factors?
- 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
