Clinical pathology Flashcards
What is the purpose of clinical chemistry?
- To assess for disease
- To assess for organ function
- Assess metabolic function
What substances in the blood are assessed for in a blood pcv?
- Enzymes
- Proteins
- Albumins
- Globulins
- Electrolytes
- Na
- K
- Cl
- Minerals
- Lipids
What other tests can be done in apart from haem?
All comes under clinical pathology
- Cytology
- Endocrinology
- Urinalysis
- Drug assays
- Molecular testing
- Immunohistochemsitry and flow cytometry
What are the advantages and disadv. of serum or plasma?
Serum is only obtained after leaving to clot for a minimum of 30 minutes.
Most biochemistry tests can be performed on plasma or serum.
Type of anticoagulant used to obtain plasma may impact ability to do tests though.
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When are enzymes used?
Assays often assessing function
Enzymes often require co-factors to catalyse substances
End point often a colour change
How do you know whether the result is significant?
Reference intervals and doses taken at 95% etc. Using standard deviation and mean results will make up a reference curve for the results to be interpredid by.
When do you take a sample?
Starving for 8-12 hours or 24 hours is useful.
Or
Sampling when clinical effects is most apparent-post seizure
Or
Peak times of when using drug analysis.
What is albumin?
One of the smallest proteins commonly found in plasma/serum.
Synthesised in the liver
Increases seen with dehydration
decreases will reflect:
- increased loss of albumin
- decreased production/negative acute phase protein
What is globulins?
Increases antigenic stimulation
Decreases due to loss of:
- Haemorrhage
- PLE
- PLN
- Decreased production or over increased protein catabolism
Whats azotaemia?
Elevation of urea and creatine
-could be:
pre renal
renal
post renal
could be due to:
- hydration status of the patient and
- USG
-
What could pre renal azotaemia be due to?
Dehydration- most commonly second to vomiting
What could be post renal azataemia be due to?
Obstruction- full bladder, possible history of stranguria
Ruptured bladder- post obstruction or RTA
What could renal azataemia be due to?
Due to renal failure, acute/chronic
Whats ALT and the consequences?
Alanine aminotransferase
Hepatocellular, most present in cells
Transient increase seen in liver damage.
Elevations may not correspond with degree of liver damage.
What ALP and the consequences?
Alkaline phosphatase.
Sensitive but not specific for cholestasis. Released from the brush broders of bile duct.
What GGT and the consequences?
Specific test for cholestasis and biliary tree disease
Less sensitive than ALP
Whats bilirubin and the consequences?
Increases may be pre hepatic, hepatic and post hepatic.
Pre hepatic:
Haemolysis, check HCT
Hepatic, post hepatic,
cholestasis
Whats bile acids and the consequences?
Functional test for the liver
Whats ammonia and the consequences?
Functional test for hepatocytes.
Elevations may also be seen following exposure to air
Need to seperate from EDTA plasma immediately.
Whats cholesterol and the consequences?
Metabolised within the liver
Inversely proportional to T4. Increases seen with
- hepatic disease
- endocrine disease
- nephrotic syndrome
decreases seen with:
malabsorption
hyperthyroidism
Whats creatine kinase and the consequences?
Indicative of muscle cell leakage/damage
Rapid elevation and relatively short life. AST has a slower response, but elevations may persist for longer.
What is urinalysis?
Assess with the current hydration, Free catch of cystocentesis
Gross appearence USG, Dipstick, Sediment, Culture, Cytology.
Where would you see calcium oxalate cyrstals usually?
In ethylene glycol poisoning
What are the different types of sampling?
Fine needle aspiration/Fine needle biopsies/crocidile clipping/ surface impression smear/swab collection
When do neutrophils come about and what do they look like?
They predominate in acute inflammation and can be degenerate. Swelling of cells with fuzzy outlines, most commonly in gram negative sepsis. https://s3.amazonaws.com/brainscape-prod/system/cm/173/647/407/a_image_thumb.png?1451145523
When do macrophages come about and what do they look like?
Common in chronic inflammation. They are phagocytic and has cellular debris usually with foreign material.
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When is lymphocytic inflammation most common?
Most common in chronic inflammation. With a mixed population of lymphocytes and plasma cells. https://s3.amazonaws.com/brainscape-prod/system/cm/173/673/391/a_image_thumb.png?1451145739
When is eosinophilic inflammation most common? and what does it look like?
Hypersensitivity/allergic reaction and hypereosinophilic reaction
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How do you determine in cytology?
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What determines whether its a sarcoma or a carcinoma? and what does this mean?
-Round cell tumours
from haematopoietic cells (mesoderm)
-Epithelial tumours
oma, carcinoma (benign)
prefix adeno (glandular)
-Mesenchymal tumours
oma or sarcoma (benign)
When is a round cell come about and what is the significance?
Round to oval in shape. High nucleus to cytoplasm ratio. Arranged in sheet like patterns.
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When are epithelial cells most common and why do they come about?
They are arranged in sheets, clusters etc.
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What are the criterias of malignancies?
- Anisocytosis (pleomorphism)
- Anisokaryosis (variation in nuclues size_
- Increased nucleus to cytoplasm ratio
- Bi, multinucleation
- coarse chromatin pattern
- Nucleoli, increased number and size. abnormal shapes
- Increased mitotic rate
- Aberrant mitotic figures
When do mesenchymal cells come about and why?
Arrangement in aggregates often haphazard or individual aggregates. https://s3.amazonaws.com/brainscape-prod/system/cm/173/674/278/a_image_thumb.png?1451147484
What are the pitfalls of cytology?
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Whats a common endocrine disorder in dogs and whats it do?
Cushings syndrome
Also known as hyperadrenocorticism, increased levels of cortisol.
May be rapidily increased with stimulus. Can be affected by many things.
Must have a good clinical suspicion of testing.
Can be caused either by a tumour of the pituitary gland in the pars distalis.
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What is the test for cushings?
Low dose dexamethasone suppresion test.
Take basal sample, adminster a low amount of dexamethasone.
Measure cortisol and their levels 4 to 8 hours after adminstration.
In HAC: the dexameth. will escape after 8 hours. There is no suppression.
What is the other test for cushings?
ACTH stimulation test.
Take basal sample.
Adminster ACTH sample
HAC will have ACTH levels above normal.
When horsings get HAC why is it different to a dog get HAC?
A horse will get the pituitary tumour in the pars intermedia rahter than pars distalis.
What tests can you use for HAC in a horse?
Equine testing dextamethasone suppression test. Unusual results in a ppid horse have increased post dextramethasone serum.
Whats the difference between cushings and addisons?
Cushings is hyperadrenocorticism- too much adrenaline.
Addisons is hypoadrenocorticism- too little adrenaline.
How do you test for addisons?
Exact same ACTH stimulation but expect low basal numbers than the average.
What disease affecting the thyroids is most common in dogs but differnet in cats?
Dogs- Hypothyroidism: To low total output
Cats- Hyperthyroidism: to high total output
What thyroid hormones do you know?
T4, T3, TSH (thyroid stimulating hormones
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How do you test for feline hyperthyroidism?
Measure the total T4 protein- increase in amount of T4
How do you test for canine hypothyroidism?
Low total T4
Increased TSH but low T4 due to bad thyroid refer to the other diagram.
Some drugs can also alter the T4
What is dynamic testing and what can it split into?
Suppression of the hormone production
Maximal stimulation of production
What are the major reasons for analyzing patient samples via laboratory procedures?
To detect an unidentified pathologic state
To define, classify, or confirm a pathopsychological disorder or disease state.
To assess changes in a pathologic state either due to a natural progression of the disease or medical therapy.
What is the distribution in this graph?
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On the left it is a gaussian distribution. On the right it is a positive skewness distribition.
How do you determine the specificity and sensitivity of results?
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