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Veterinary Clinical Pathology > Intro and Laboratory Principles > Flashcards

Flashcards in Intro and Laboratory Principles Deck (51)
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1
Q

What is Clinical Pathology?

A

Hematology, clinical chemistry, exfoliative cytology, urinalysis, endocrinology, clinical immunology, toxicology

2
Q

Reasons for testing

A

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

3
Q

Understanding reference intervals

A

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”

4
Q

What is the chance of an abnormal test result when testing a healthy animal?

A

5% chance when 1 analyze measured; 64% chance when 20 analytes measured

5
Q

Factors affecting reference intervals

A

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”

6
Q

Most common laboratory error

A

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

7
Q

Blood samples getting old cause what cellular changes? and these changes affect what blood cell measurements.?

A

cell lysis
erythrocyte swelling -> affects MCV, MCHC, PCV
platelet activation -> affects MPV and platelet count

8
Q

Platelet, leukocyte, and erythrocyte clumps could affect which blood cell measurements?

A

number/microliter blood decreased
platelets counted as leukocytes
MCV, MCHC, electronic HCT
MPV increased

9
Q

What additive helps with platelet and leukocyte clumping?

A

citrate

10
Q

Clot formation affects what blood cell measurements

A

all cell types decrease

11
Q

Purple top tubes have what additive?

A

EDTA

12
Q

Green top tubes have what additive?

A

Lithium heparin

13
Q

Blue Top tubes have what additive?

A

citrate

14
Q

What interfering substances cause analytical errors?

A

hemolysis, lipemia, hyperbilirubinemia

15
Q

Falsely elevated potassium concentrations in horses and cattle can be due to what laboratory error/cellular process?

A

hemolysis - they have high K in RBCs

16
Q

What three visual factors do you need to evaluate before examining blood samples?

A

color - tomato soup vs. syrump (methemoglobinemia)
Agglutination vs. rouleaux -if rouleaux you can use saline 10:1 to separate
is it mixed well?

17
Q

Define rouleaux

A

“stack of coins” - due to non-specific binding of RBCs due to high protein content in the blood, will disperse with saline

18
Q

Define agglutination

A

clumping of RBCs due to specific binding of RBCs by antibodies when IMHA is happening, will not disperse with saline test

19
Q

What conditions cause lipemia in blood samples?

A

When animals not fasted before blood collection or with hyperlipidemic syndromes

20
Q

How does lipemia affect blood samples?

A

causes turbidity
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)

21
Q

Give an example of a post-analytical laboratory error.

A

Error in data transcription

22
Q

What are the four components of a microhematocrit tube after spinning?

A

plasma, buffy coat, packed red blood cells, wax plug

23
Q

Three conditions that affect the appearance of the plasma in a microhematocrit tube?

A

hemolysis, lipemia, icterus

24
Q

What types of cells are in the buffy coat?

A

leukocytes and platelets

25
Q

What is fibrinogen and why is it important?

A

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

26
Q

What are the functions of plasma proteins?

A
transport of nutrients, hormones, waste and drugs
colloid osmotic effects
acid-base
immunity
hemostasis
27
Q

Where are most plasma proteins synthesized?

A

in the liver - big problem if liver failures

28
Q

Why do adults tend to have higher concentrations of plasma proteins than neonates?

A

exposure to antigens

29
Q

What is the composition of plasma?

A

92% water

8% solids - nutrients, proteins, hormones/enzymes, and electrolytes

30
Q

Functions of plasma

A

transport of nutrients
transport of by-products and waste
transportation of cells
maintain homeostasis (pH, temp, etc.)

31
Q

What important things do you evaluate on peripheral blood film?

A

red blood cell density - anemia?

RBC size, shape, color, and inclusions

32
Q

What is a normal PCV?

A
Roughly 30-50% 
Canine - 37-54
Feline 30-47
Equine 32-47
Bovine 24-46
33
Q

What is a normal plasma protein (TP)?

A

Roughly 6.0-8.0 g/dL

34
Q

What is a normal plasma color?

A

dogs and cats: colorless

horses and bovines: colorless or pale yellow

35
Q

What blood cell characteristics are analyzed by an automated hematology analyzer?

A

Quantity - RBC #/microliter, hemoglobin concentration/deciliter, hematocrit percentage
Quality - mean cell volume (size of RBCs), red cell distribution width (size variation of RBCs), mean cell hemoglobin concentration (hemoglobin within RBCs)

36
Q

MCV

A

Describes average size of RBC

37
Q

RDW

A

red cell distribution width - describes how much variation there is in RBC size, corresponds to the standard deviation of RBC mean cell volume; =SD/MCV, when RBC cell size is more variable than normal - RDW is increased

38
Q

When calculated hematocrit and spun PCV are not within 3% of each other which do you trust?

A

spun PCV - certain diseases cause HCT to be false because it is a calculation not a direct measurement

39
Q

MCHC

A

ratio of hemoglobin to the number of RBCs
decreased = regenerative anemia, iron deficiency anemia
increased = artifact! not real ( could be due to hemolysis, lipemia, heinz bodies, WBC elevation)

40
Q

Heinz bodies cause what types of errors in blood cell measurement?

A

Hb and MCHC increased

sometimes total leukocyte counts increased

41
Q

nucleated erythrocytes cause what error in blood cell measurement?

A

often counted as luekocytes

42
Q

You should never trust an automated ______ count in cats

A

platelet - cats are very prone to platelet clumping

43
Q

Name the four types of blood film stains and what you use them for.

A

Romanowsky type stains (Wright, Wright-Giemsa, Diff-Quik) - evaluation of RBCs
New Methylene Blue - reticulocytes, NMB wet prep
Prussian Blue - look for Iron
Cytochemical - ??

44
Q

Describe ideal procedures for blood sample collection and handling

A

kept cool during storage and shipping - wrapped in paper towels to avoid direct contact with ice
blood smears made from freshly collected blood, not stored and transported blood
use DI water instead of tap

45
Q

What does a water artifact look like?

A

moth eaten appearance of cells
refractile artifact - looks bright in one plane, dark in another
can be mistaken for RBC inclusion

46
Q

Age related changes in RBCs

A

crenation - echinocyte formation
lysis - decrease RBC and HCT, falsely high MCHC
Hgb crystallization
cellular swelling - falsely high MCV ( and thus HCT), decreased MCHC

47
Q

Age related changes in WBCs

A

swelling and smoothing of nuclear chromatin (looks like band neutrophil formation)
pyknosis and karyhorrhexis of nuclei
cell smudging
prominence of Dohle bodies
pyknotic leukocytes look like nucleated RBCs - can be misinterpreted

48
Q

Age related changes in platelets

A

clumping- decreases platelet count and increases MPV (small clump seen as single large platelet), large platelet clumps are excluded from count altogether
degranulation (makes them difficult to see and enumerate)

49
Q

The three parts of a blood smear

A

base, feathered edge, “counting area”

50
Q

What do you analyze in the monolayer of a blood smear slide?

A

right behind feathered edge - cells spread, not overlapping and not disrupted so analyze size and shape of RBCs, WBCs uniform distributed in this section

51
Q

What should you analyze in the feathered edge of a blood smear slide?

A

detect platelet clumps and microfilaria