Flashcards in Intro and Laboratory Principles Deck (51)
What is Clinical Pathology?
Hematology, clinical chemistry, exfoliative cytology, urinalysis, endocrinology, clinical immunology, toxicology
Reasons for testing
health screen, screen for disease, identify specific organ involvement, confirm presumptive diagnosis, confirm abnormal test, determine disease severity, formulate prognosis, monitor therapy or disease progression
Understanding reference intervals
2.5% of the healthy population will have values beyond either side of the median 95% and be deemed "abnormal" even though they are fine; is a compromise that increases the sensitivity of the test for recognizing sick animals because only a few healthy animals will be viewed as "abnormal"
What is the chance of an abnormal test result when testing a healthy animal?
5% chance when 1 analyze measured; 64% chance when 20 analytes measured
Factors affecting reference intervals
species, age, sex, time postprandial, time of day, emotional state, activity level, pregnancy/egg-laying, diet, region, time of year, generally collect overnight fasting samples from adult animals to increase chances of "normal"
Most common laboratory error
pre-analytical - ie. improper handling of samples (labeling), wrong anticoagulant/improper ratio of anticoagulant, traumatic blood draw or transfer of blood into tubes causing hemolysis
Blood samples getting old cause what cellular changes? and these changes affect what blood cell measurements.?
erythrocyte swelling -> affects MCV, MCHC, PCV
platelet activation -> affects MPV and platelet count
Platelet, leukocyte, and erythrocyte clumps could affect which blood cell measurements?
number/microliter blood decreased
platelets counted as leukocytes
MCV, MCHC, electronic HCT
What additive helps with platelet and leukocyte clumping?
Clot formation affects what blood cell measurements
all cell types decrease
Purple top tubes have what additive?
Green top tubes have what additive?
Blue Top tubes have what additive?
What interfering substances cause analytical errors?
hemolysis, lipemia, hyperbilirubinemia
Falsely elevated potassium concentrations in horses and cattle can be due to what laboratory error/cellular process?
hemolysis - they have high K in RBCs
What three visual factors do you need to evaluate before examining blood samples?
color - tomato soup vs. syrump (methemoglobinemia)
Agglutination vs. rouleaux -if rouleaux you can use saline 10:1 to separate
is it mixed well?
"stack of coins" - due to non-specific binding of RBCs due to high protein content in the blood, will disperse with saline
clumping of RBCs due to specific binding of RBCs by antibodies when IMHA is happening, will not disperse with saline test
What conditions cause lipemia in blood samples?
When animals not fasted before blood collection or with hyperlipidemic syndromes
How does lipemia affect blood samples?
can interfere with anything that is measured by spectrophotometric assays
can dilute out normal substances like electrolytes in the aqueous component of the serum resulting in falsely decreased concentration (ion exclusion effect)
Give an example of a post-analytical laboratory error.
Error in data transcription
What are the four components of a microhematocrit tube after spinning?
plasma, buffy coat, packed red blood cells, wax plug
Three conditions that affect the appearance of the plasma in a microhematocrit tube?
hemolysis, lipemia, icterus
What types of cells are in the buffy coat?
leukocytes and platelets
What is fibrinogen and why is it important?
acute phase protein, precursor to fibrin in coagulation - important because it increases with inflammation so it can indicate infection in large animals that don't have dramatic neutrophilic responses; present in plasma but not serum because it is used up in clotting process - causes optimal platelet aggregation
What are the functions of plasma proteins?
transport of nutrients, hormones, waste and drugs
colloid osmotic effects
Where are most plasma proteins synthesized?
in the liver - big problem if liver failures
Why do adults tend to have higher concentrations of plasma proteins than neonates?
exposure to antigens
What is the composition of plasma?
8% solids - nutrients, proteins, hormones/enzymes, and electrolytes