Clinical Pathology Flashcards
What are the 4 components of a CBC that you need to look at the numbers and morphology of?
- erythron
- leukon
- thrombon
- total plasma protein + fibrinogen
What type of tests are CBC, Chemistry, urinalysis, and blood gas?
screening tests
you must put the results of these tests in context with the physical exam findings.
When looking at the erythron component on a CBC, what should you consider?
- RBC mass (RBC count, HGB, HCT/PCV)
- RBC indices (MCHC, MCV)
- RBC morphology
- RBC regeneration (reticulocyte count and %, morphological changes)
what is the calculation that can be done to obtain HCT?
HGB x 3
= HCT +/- 1-3
ex. if the HGB was 5.5, mulitply that by 3 and you’d get a HCT of ~15.
When looking at the leukon component of a CBC, what must you examine/consider?
- leukocytosis (neutrophilia, lymphocytosis, monocytosis, or eosinophilia/basophilia)
- leukopenia (neutropenia, lymphopenia, monocytopenia, basopenia)
List the potential reason for the following CBC changes:
A. Neutrophilia
B. Lymphocytosis
C. Monocytosis
D. Eosinohilia/Basophilia
E. Neutropenia
F. Lymphopenia +/- Eosinopenia
G. Monocytopenia and Basopenia
A. Neutrophilia – inflammation, epinephrine, corticosteroid
B. Lymphocytosis – epinephrine (physiologic), chronic inflammation
C. Monocytosis – stress, increased demand for macrophages
D. Eosinohilia/Basophilia – worms, etc.
E. Neutropenia – overwhelming inflammation
F. Lymphopenia +/- Eosinopenia – corticosteroid/stress
G. Monocytopenia and Basopenia – n/a ?? lol
When looking at the thrombon component, what could you examine/consider?
- platelet count – thrombocytosis or -penia
- platelet estimation – are there any clumps?
- platelet morphology
- platelet function (BMBT, aggregometry, flow cytometry)
- vWF
- coagulation factors (PT/PTT)
- fibrinogen
- FDPs/D-Dimers
- Global hemostasis –> thromboelastogram
What is an indication for performing serum protein electrophoresis?
When you have unexplained hyperglobulinemia
Can determine cancer vs inflammation
what can tell you about energy metabolism in the patients body?
- carbohydrates – glucose, fructosamine
- lipids – cholesterol, triglycerides, ketones, NEFAs
what are 3 PRIMARY ways to assess renal function?
- creatinine
- BUN
- urinalysis UPC
what are 4 SECONDARY ways to assess renal function?
- albumin
- minerals
- electrolytes
- acid-base
what is the equation for corrected chloride?
average Na / measured Na
x measured Cl
for ex. if average Na is 143, measured Na is 155, and
measured Cl is 134… 143/155 x 134 = 124 (the corrected Cl)
what are 5 markers of liver injury?
- ALT
- AST
- GDH
- SDH
- LDH
what are ways to examine liver function?
- albumin
- BUN
- glucose
- cholesterol
- coagulation factors
- conjugated bilirubin
- fibrinogen
- ammonia
- bile acids
- RBCs
What markers can you look at for suspicion of cholestasis?
- ALP*
- GGT*
- Bilirubin
- Urinalysis
what is the primary indicator of muscle injury?
CK
what are secondary indicators of muscle injury?
- AST
- LDH
- K and P
- myoglobin in urine
How can you assess pancreas health/function?
- lipase
- amylase
- trypsin-like immunoreactivity (TLI)
- pacreatic lipase immunoreactivity (PLI)
- cobalamin
- folate
what is the MOST specific and sensitive test for pancreatitis in dogs and cats?
Pancreatic lipase immunoreactivity (PLI)
in house rapid tests (SNAP cPL and fPL) are NOT as reliable as lab send out tests.
Interpret the following:
A. Amylase and Lipase Increased >3-4x URI suggestive of ___________.
B. Amylase and Lipase increased <3-4x URI may be due to ___________.
A. Amylase and Lipase Increased >3-4x URI suggestive of PANCREATITIS.
B. Amylase and Lipase increased <3-4x URI may be due to DECREASED GFR ALONE.
note: normal AMS or LPS does not rule out pancreatitis
what test is used to detect/rule out exocrine pancreatic insufficiency (EPI)?
TLI (if decreased = diagnostic)
what tests are best for diagnosing a malabsorptive disease?
- folate (absorbed by prox SI; if decreased –> SI dz or dietary def; if increased –> SIBO, EPI, excess suppl, etc.)
- Cobalamin/VitB12 (absorbed by distal SI and ileum; if decreased –> EPI, SIBO, ileal dz, etc.)
results of these tests are ONLY meaningful if pancreatic function is NORMAL and the condition is chronic. Further tests are usually req.
How do you obtain reference intervals?
Mean +/- 2 SD
reference intervals vary with equipment, methodology, location, and patient.
what is the minimum number of animals tested to have a reliable reference interval?
40 is the minimum
ideally, you want 120.
Which of the following is considered a PREANALYTICAL error?
A. inappropriate test request
B. instrument malfunction
C. improper data entry
D. operator error
A. inappropriate test request
B and D are examples of analytical error
C is an example of post-analytical error
Which of the following is considered ANALYTICAL error?
A. misidentification or label error
B. insufficient sample volume
C. inappropriate container or sample
D. inappropriate reagent
E. sample processes before analysis
F. inappropriate reference interval
D. inappropriate reagent
A, B, C, and E are pre-analytical errors
F is post-analytical
Which of the following is considered a POST-ANALYTICAL error?
A. incorrect interpretation of results
B. inappropriate methodology
C. inadequate transport or storage
D. order entry or error on request form
F. instrument malfunction
A. incorrect interpretation of results
B and F are analytical errors
C and D are pre-analytical errors
what are important quality control / quality assurance measures that can be taken to avoid preanalytical, analytical, and postanalytical errors?
- SOPs
- Train personnel
- Automation
- Monitor results
- Communication with vets/clients
- Certification
If you have a healthy patient presenting for an elective surgery, but you receive abnormal chemistry results (low Alb and high ALT), how would you handle this?
recheck abnormal values
If you have a healthy patient presenting for an elective surgery, but you receive abnormal chemistry results (low Alb and high ALT).
You recheck these values and they are now normal / within the reference interval.
What is your plan?
- You could recheck again to be safe
- or you could run additional exams to eval where the albumin went
- or you can proceed with the surgery because it is likely that those first abnormal values were erroneous d/t the dog being clinically healthy.
A patient presents to your clinic for acute onset of lethargy. You run a chemsitry and receive these abnormal results: low glucose (4), low calcium (0), high potassium (20), low HCO3 (5), and high AG (39).
What can explain these findings?
pre-analytical error!
- maybe the sample was not collected correctly (collected in K3EDTA purple top tube which chelates Ca and elevates K)
- maybe the plasma was not harvested from the cells and the glucose was consumed by the cells??
- maybe the sample was exposed to air –> loss of CO2 –> decreased bicarb –> increased AG.
A patient presents to you with dysuria and discolored urine. You feel an enlarged prostate on your rectal exam. You see an enlarged prostate on ultrasound, so you perform cystocentesis and send for cytology. You also send out a urinalysis.
The cytology results indicate bacterial infection and prostate hyperplasia, but the urinalysis is normal. How did this occur?
error – could be pre analytical, analytical or post analytical
what tube color(s) is/are best for serum samples used in chemistry tests?
red top, yellow top, green top
all contain a clot activator
what tube color(s) is/are best for hematology (CBC) testing?
purple top (contains EDTA)
green top (contains heparin)
what is the BEST collection method to avoid coagulation occurring while taking the sample?
use a vacutainer
what color(s) tube is/are appropriate for glucose/lactate tests?
grey top (contain sodium flouride)
what color(s) tube is/are appropriate for coagulation tests?
light blue top (contains sodium citrate)
what effect can EDTA have on red blood cells with regard to the hematology results?
can decrease MCV and HCT
what effect can heinz bodies have on red blood cells with regard to the hematology results?
can increase MCH, MCHC, reticulocyte (% and #), and platelets.
what effect does using an OLD sample have on the leukon in hematology results?
dohle bodies
decreased WBC
decrease neutrophil %
increased band %
inc/dec lymphocyte %
platelet clumps falsely _____ the platelet count
decrease
Ghost cells falsely _______ the platelet count
increase
infectious organisms falsely _______ platelet count.
increase
T/F: stain precipitate is commonly mistaken for bacterial organisms
true
T/F: icterus causes no interference on the CBC
true
Why does delayed analysis cause artifact with urinalyses?
Delay causes the following…
- urine pH increases
- microbial proliferation occurs
- degradation of cells/casts
- degradation of bilirubin, ketones
- calcium ox. and mag ammonium phosphate crystals may develop
What steps can you take to reduce artifacts in cytology samples?
- wear gloves when handling slides
- never reuse slides
- let slides air dry
- do not heat fix
- stain slides as soon as possible
- never send slides with formalin tissues in same box
- provide relevant hx
- be precise about location of lesion
T/F: all assays have a degree of error.
true do not over-interpret changes in lab data.
T/F: reference values from one lab cannot be compared directly to values from another.
true each lab uses its own reference intervals.
