Lab Flashcards
identify what this blood tube is
serum tube
what is found within serum tubes?
CAT beads
what is the role of CAT beads in serum tubes?
encourage clotting to occur faster
makes sample more stable
what are serum tubes used for?
biochem
hormonal assays
serology
what are you assessing during serology?
antibodies
identify what this blood tube is
lithium heparin
what is the role of heparin tubes?
biochem in house
what is the benefit of heparin tubes?
tests can be run straight away
why can tests on blood in a heparin tube be run straight away?
anticoagulant present
identify this blood tube
EDTA
what are EDTA tubes used for?
haematology
identify this tube
citrate
what are citrate tubes used for?
coagulation profiles
identify these tubes
oxalate
what are oxalate tubes used for?
glucose - rare thanks to glucometers
what is the difference between serum and plasma?
serum has been allowed to clot on it’s own so contains no clotting factors as they have been used
why does plasma contain clotting factors?
collected in tubes that contain anticoagulant - no clotting factors used
does serum or plasma contain clotting factors?
plasma
what tubes contain anti-coagulant?
heparin
EDTA
citrate
oxalate
what order should tubes be filled?
serum
heparin
EDTA
what tube must be filled last?
EDTA
why must EDTA be filled last?
binds calcium
why is calcium binding of benefit in EDTA tubes?
prevents clotting
what results are seen on EDTA contamination of biochem samples?
low calcium
high potassium
why is high potassium seen with EDTA contamination of biochem?
2 molecules of K+ attached to each EDTA molecule
why are heparin tubes of benefit for emergency patients?
can be used to run tests immediately
what do reference ranges include?
95% of healthy animals
why doe reference ranges only include 95% of healthy animals?
top and bottom 2.5% disregarded as not representative of population as a whole
what is low total protein known as?
hypoproteinaemia
how is a deviation from the reference range defined as mild?
within the ‘window’ of the reference range
if ref range is 20, 20 above or below is ‘mild’
how is a deviation from the reference range defined as moderate?
outside or up to double the ‘window’ of the reference range
if ref range is 20, 20-40 above or below is ‘moderate’
how is a deviation from the reference range defined as marked?
3-4x the ‘window’ of the reference range
if ref range is 20, more than 40 above or below is ‘marked’
what is hypoalbuminaemia?
low albumin
make sure you practice some reference ranges
ok!!
what does ALT stand for?
alanine aminotransferase
what does ALP stand for?
alkaline phosphatase
what does GGT stand for?
Gamma-glutmyl transferase
what is hyperbilirubinaemia?
high bilirubin within the blood
what is hypocholesterolaemia?
low cholesterol within the blood
what is low calcium?
hypocalcaemia
what are the main causes of high ALT?
primary hepatopathy
secondary to cholestasis
artefact
due to muscle damage
what is cholestasis?
bile not moving as it should out of the GB
how can a patient with elevated ALT be checked to see if it is muscle related?
check CK as muscle specific
what are the markers of hepatocellular damage?
ALT
AST
GLDH
SDH
what is indicated by ALT, AST, GLDH, SDH?
hepatocellular damage
what is occuring during hepatocellular damage?
cells leaking hepatic enzymes
what are the markers of cholestasis?
ALP
GGT
what is indicated by ALP and GGT?
cholestasis
what are the 2 types of liver function marker?
substances produced in the liver
substances conjugated and excreted by the liver
what substances are produced in the liver that can be used to measure function?
cholesterol
urea
glucose
albumin
some globulins
coagulation factors
what substances are conjugated and excreted by the liver that can be used to measure function?
bile acids
bilirubin
what can cause primary hepatocellular disease?
trauma
toxins
drugs
inflammation/infection
neoplasia
intrahepatic cholestasis
bile toxicity
what are the secondary causes of hepatocellular disease?
non-specific
many!!
liver is sensitive soul
what indicates primary causes of decreased hepatic function?
functional changes: increased levels of substances excreted and decreased levels of substances produced
what may increase if decreased hepatic function is seen?
bilirubin
bile acids
- should be excreted but liver can’t
what may decrease if decreased hepatic function seen?
albumin
cholesterol
urea
glucose
clotting factors
- should be being made but liver can’t
how can xylitol toxicity be treated?
plasma transfusions to increase protein levels
vitamin K to support clotting factor formation
IVFT to clear toxins and support BP
antibiotics as immunocompromised due to reduced globulin
what complications can be seen with xylitol poisoning?
DIC
what are the signs seen with a classic stress leukogram?
neutrophilia
monocytosis
lymphopenia
eosinopenia
what does SMILED mean?!
Segmented neutrophils and Monocytes Increase
Lympocytes and Eosinophils Decrease
are all 4 components of the stress leukogram always seen?
no - 2-3 common
monocytosis v rare
what is an acanthocyte?
changes to RBC cell membrane causing fingerlike projections
where are acanthocytes seen?
old blood
artefact
toxin ingestion
why can mild electrolyte changes be so concerning?
even small changes can affect physiology (e.g. K+) and have catastrophic effects (e.g. bradycardia or arrest)
what tests may be sued if azotemia is seen?
urinalysis
US
what is hypersthenuria?
concentrated urine
what is hyposthenuria?
dilute urine
what is isosthenuria?
same SG as blood - kidneys not working
what urine concentration is seen in kidney disease?
isosthenuria
what may be seen on urinalysis that indicates AKI?
inappropriate urine conc
glucose
tubular casts
how is ethylene glycol toxicity treated?
IVFT
supportive care
ethanol
what is caused by ethylene glycol ingestion?
AKI
what can be indicated by absence of stress leukogram?
chronic disease
immunosuppression
BM disease
what is liver prone to on biochem?
secondary enzyme elevations
how can you tell if secondary liver enzyme elevation has occurred?
GGT and ALP normal
what must lab findings be used in conjunction with?
clinical signs
what must be considered when assessing what blood results are clinically significant?
reference interval
species
significance of parameter itself
magnitude of change
clinical history
what is the purpose of cytology?
screening test to look for cells in fluid and tissue samples
where may fluid be acquired from for cytology?
BAL
CSF
synovial fluid
body cavities
where may tissue samples be acquired from for cytology?
lumps
bumps
lymph nodes
what clinical information is critical when assessing a lesion that cytology will be performed on?
clinical history
lesion evolution over days/weeks/months
previous treatment
characteristics of the lesion itself
how can lesions be characterised?
location
are they firm / soft
dimensions
painful or non/painful
ulceration present
depth (cutaneous or subcutaneous)
adherent or non-adherent
how aspirate appears
what are the 2 techniques for FNA?
suction
non-suction
what is suction FNA used for?
hard cutaneous or subcutaneous masses
bone lesions
non-suction technique unsuccessful
what is non-suction FNA used for?
soft cutaneous or subcutaneous masses
lymph nodes
vascular lesions/organs
describe how to perform suction FNA
negative pressure applied to syringe and needle while needle is redirected within the mass
pressure relaxed before needle removed
when applying negative pressure for suction FNA what should happen before the needle is removed?
pressure/suction relaxed before needle removed
describe how to perform non-suction FNA
needle dug around in tissue without syringe attached
needle is removed
air placed in syringe and then needle attached
air used to put sample onto slide
what are the main smear techniques for slide preparation?
line
squash
twist
spatter (not ideal!)
how is the squash technique of slide preparation performed?
using two slides placed against each other spread from the frosted edge upwards
be gentle so that cells are not crushed
aside from FNA what are other collection methods for cytology samples?
impression smear
scrape
imprint biopsy
imprint through rolling cotton bud for ear samples
what can be assessed when using a skin scape sample?
mites
what organism is commonly seen on ear cytology?
malassezia
what organism is malassezia?
fungus - yeast
what organism is seen here?
malassezia (yeast)
is malassezia seen on normal skin?
yes in low numbers
what indicates malassezia infection?
multiple organisms per HPF
how should cytology slides be dried?
quickly - hairdryer on cool or air fixation
what must be done with cytology slides before staining and packing?
ensure they are completely dry
what should all slides be labelled with?
patient ID
site
date
what is the most common staining technique used in practice?
Diff-Quick
what are some stains used in commercial labs?
Giemsa/Modified Wright
Methylene blue
Toluidine blue
ziehl/Nielson
what is Toluidine blue used to stain?
MCT samples
what is useful about Toludine blue for MCT staining?
histamine granules show up well
what is Diff-Quick solution A (blue) made up from?
Methanol
what is Diff-Quick solution A (blue) used for?
fixation
what is Diff-Quick solution B (red) made up from?
Eosin
what is Diff-Quick solution C (purple) made up from?
Methylene blue
what is Diff-Quick solution B (red) used for?
Eosionophilic (base) staining
what is Diff-Quick solution C (purple) used for?
basophilic (acid) staining
why should diff quick stains be replaced regularly?
methylene blue deteriorates quickly
should the same Diff-Quick stains be used for all samples?
should have clean and then dirty set for dermatology
what cells are seen in this picture?
neutrophils
what power of lens is found in the eyepiece of a microscope?
10
what is the combined power of the eyepiece and lens on a microscope?
lens power x10 for eyepiece
what should be assessed on low magnification (10x)?
cellularity
preservation
staining
haemodilution
cell distribution
background
assess cellularity in this image
low
assess cellularity in this image
high
what is haemodilution?
RBC present in sample
what is the total magnification of the 40x lens?
400x human eye
what is assessed on the high magnification (40x) lens of a microscope?
cellular vs non-cellular elements
inflammatory vs neoplastic
malignant vs benign
what is assessed on the high magnification (100x) lens of a microscope?
presence of cytoplasmic granules
nuclear detail
presence of pathogens (bacteria, fungi, protozoa)
what indicates inflammation on cytology?
neutrophils
how do neutrophils appear on cytology?
clear nuclear outlines with dark purple chromatin
cytoplasm is pale and clear/slightly pink
what are degenerate neutrophils?
neutrophils affected by toxic change (e.g. infection)
how do degenerate neutrophils appear under the microscope?
loss of segmentation
lighter colored ‘fluffy’ nuclear chromatin and swollen appearance
does the absence of bacteria on a slide mean there is no infection?
no if neutrophils present - culture should be performed
what cells are seen in this image?
non-degenerate neutrophils
what cells are seen in this image?
degenerate neutrophils
what is seen on this slide?
MCT - many histamine granules
what is seen on this slide?
evidence of lymphoma
what is seen on this slide?
adipose tissue indicative of lymphoma
what are the benefits of cytology?
easy
quick
cheap
relatively non-invasive
what are the limitations of cytology?
screening test not confirmatory
what is needed to to confirm suspicions seen on cytology?
histology
why is QA/QC important for lab machines?
life/death/diagnostic decisions will be made based on results given so they must be correct
how can QA/QC be maintained?
set-up correctly
maintain analysers and systems
interpret results
carry out controls
ensure accurate record keeping
what are the advantages of in house labs?
fast turn around time
potential for improved patient monitoring
smaller sample volume needed
available OOH
available in remote areas
may save costs
what are the 2 major variations which affect results?
biological
analytical
what factors affect results prior to sampling?
biological
what are the biological variables that may affect results?
inter-individual
intra-individual
what are inter-individual factors?
inherent differences between groups of animals due to effects of species, breed, age and/or sex
what are intra-individual factors?
transient differences in the same animal
what are intra-individual factors due to?
environmental or external factors
what are some examples of intra-individual factors?
diet (recent meal)
stress/excitement
reproductive status/lactation
drugs
can intra-individual factors be eradicated?
no but should be minimised as much as possible
what are the analytical factors that can affect results?
pre-analytical
analytical
post-analytical
when do pre-analytical factors occur?
before the sample is run
what are some pre-analytical factors that may affect results?
poor sampling technique
haemolysed, lipaemic or icteric plasma
wrong anticoag to blood ratio
sterile or non-sterile container if needed
transportation
storage
what is a haemolysed sample?
one where RBCs have broken - plasma pink/red
where should samples be stored?
fridge if there is delay in testing
why should samples be stored in the fridge?
slows cell metabolism
what is the fluid limit for sending samples by post?
50ml
how must samples be packed for posting?
sealed container
leakproof bag
absorbative padding - enough to absorb all fluid if container breaks
packaged in rigid container
when do analytical factors occur?
while the test is running
should patient side and lab methods of blood testing be compared?
no - results vary significantly so should not be compared directly
what are analytical factors?
factors which cause variaton/error during the analysis of the sample and influence the final result
what are the 4 main analytical factors?
equipment
technician
analytical procedure
laboratory
is quality control a legal requirement?
no regulation just recommendations
voluntary
when should quality control be performed?
regularly according to manufacturer recommendations
what is involved in quality control?
control material of known composition is measured to check the accuracy of the analytical process as results are known
when is quality control performed?
during analysis to ensure validity of result
what should be done if a control fails?
check for obvious problems
use another tube of control materials
repeat control in full
what are some obvious reasons for control fails?
reagent depletion / expiry
mechanical faults
clots - machine clean
once a repeat control has been tried and it fails what should be done?
use new lot of reagent, re-calibrate and repeat control
then run routine maintenance and repeat control
consult manufacturer
when do post analytical factors occur?
after sample is run
what are some examples of post analytical factors?
incorrect transfer of results to the patient record
results not archived correctly
storing the specimen incorrectly / not storing for additional tests
what are the main ways to ensure QA/QC?
best sample possible
stick to maintainance routines
don’t use old reagents
check if results don’t make sense
