Lab Techniques Flashcards
What are reference intervals
The upper and lower limits for 95% of healthy animals
What percentage of animals are outliers (with concern to reference intervals)
1/20 (5%)
What is the lower reference interval
Mean - 2 Standard Deviations
What is the upper reference interval
Mean + 2 Standard Deviations
What are some reasons in which reference intervals should be used with caution
Outliers (5%) Exercise anemia in horses Food ingestion in SA
How should you interpret lab results?
ERC - Extracting, Rank, Connect Extract: all abnormal value Rank: all abnormal values (below or above RI) to mild, moderate, marked Connect: lab pattern with history and c/s
Ways of collecting blood
Whole Serum Plasma
Cytology methods
Fluids Biopsies FNAs
Urine collection methods
Free catch Cysto Catheterized
When should you collect blood from large animals? Why?
Morning - before exercise so splenic contractions dont give innacurate RBC results (may appear higher)
When should you collect blood from small animals? Why?
Morning (before meal) - to avoid collection of lipids. Lipids can cause hemolysis
What is an iatrogenic cause of hemolysis in blood collection
Needles can cause hemolysis and damage to cell morphology
What effect do clots have on blood samples
Artefact: lowers platelet, RBC and WBC counts
Which element do anticoagulants in blood tubes bind to
Calcium
What effect does excess EDTA or excess blood have on blood sample
Excess EDTA (too little blood in sample): shrinks RBCs —-> iron deficiency
Excess blood (too much in tube): clot formation
Which tube preserves cell morphology best? (TQ)
EDTA
What are 3 benefits of EDTA tube
Preserves cell morphology best
Interferes least with romanowsky stains
Prevents clot formation in joint fluids
T/F - EDTA is best for coagulation tests
False! Forms insoluble complex with Ca
Which tube is best for fish
Lithium heparin
T/F - EDTA should be frozen (TQ)
F - NEVER (cells will expand)
Which tube is best for CBC. Do you separate plasma and cells (TQ)
EDTA - no you dont separate
EDTA: in vitro hemolysis causes which artefacts
Lowers RBC Lowers PCV Increases MCHC
Which test do you use with lithium heparin (TQ)
Chemisty
Which is anticoagulant tube of choice for biochemistry?
Lithium heparin
What is the difference between serum and plasma
Serum - no platelets or clotting factors
Which is more stable - plasma or serum?
Serum. The fibrinogen in plasma increases degradation
Which is blood tube of choice for bile acids? TQ
Plain blood tube
Which is blood tube of choice for serology? TQ
Plain blood tube
Which is blood tube of choice for glucose and lactate? Why? TQ
Fluoride oxalate. It prevents RBCs from using glucose
You run an blood assay using a lithium heparate tube. Your results suggest the patient is hypoglycemic. Do you trust these results?
No - in lithium heparin RBCs stay active and will utilize glucose in blood. If you run glucose assay in lithium heparate tube, there will be an iatrogenic artefact
Which is tube of choice for coagulation tests? TQ
Sodium citrate - because it binds poorly with calcium
Do you put serum or plasma in sodium citrate tubes
Plasma
T/F - chemistry samples can be frozen (are there exceptions)
True - if analysis is >24h Exception- Ammonia!! Analyze within 60 min `
What artefacts are caused by in vitro hemolysis
Increased K+
Increased phosphate
Increased AST
Should you refridgerate or freeze your biochemistry sample if your analysis is <24h
Refridgerate
What are evidence of contamination in urine samples
Bacteria (rods, cocci) WBCs (neutrophils)
What are benefits of cystocentesis? Is it normal to see some blood
No contamination by microbes, epithelial cells May see some blood
Containers used for urine specimens
Sterile, chemical free tubes
Why do you need to examine urine specimens asap?
Bacterial multiplication may cause cell lysis and casts Causes false positive chemical reactions
Which tubes are best for bacterial culture
Sterilin tubes (or plain blood tubes)
What should you collect lavage samples in
EDTA tubes Sterilin tubes
What do you collect CSF in
EDTA
Which 2 samples do you need to analyze in <1hr
CSF - very low in protein which maintains cell integrity. Cells degrade quickly. Ammonia
What can you add to CSF to stabilize the sample
Bovine serum albumin
What type of samples are used for touch imprints
Punch biospies Necropsies
What should you do if you are sending urgent samples on a Friday evening
Call the lab
