Clinical Haematology Flashcards
1
Q
what are the erythrocyte (RBC) parameters shown on a haemogram?
A
manual reticulocyte count haemaglobin haematocrit number of RBC mean cell volume mean cell heamoglobin mean cell heamoglobin concentration
2
Q
what value on a haemogram is most often wrong?
A
platelets
3
Q
what are the main leukocyte (WBC) parameters on a haemogram?
A
total WBC neutrophils lymphocytes monocytes eosinophils basophils
4
Q
what is the best tube to used for haematology?
A
EDTA blood tube
5
Q
what does EDTA do to blood in the tube?
A
chelates (binds) calcium in the blood. This is required for clotting so EDTA prevents clotting.
6
Q
when may heparin tubes be used?
A
in some exotic species as EDTA can cause lysis
7
Q
what is essential when filling tubes for haematology?
A
respect the amount of blood required in the tube - only fill to the line
8
Q
what must you do to haematology tubes to ensure good mixing of blood with anti-coagulate?
A
gently invert the tube 10-20 times and roll
9
Q
how should blood smears be stored?
A
once dry - in slide containers
10
Q
why should blood smears not be stored in the fridge?
A
condenses the cells and leads to water artefact
11
Q
where should haematology samples be stored?
A
in the fridge until submission to the lab or running sample
12
Q
why should haematology samples not be stored in the freezer?
A
causes cell rupture
13
Q
how should haematology samples be packaged?
A
not right next to the ice pack as this may freeze them
14
Q
what parameters evaluate RBC?
A
haematocrit
packed cell volume
RBC count
15
Q
what parameters show average makeup of RBC/indexes?
A
mean corpuscular volume
mean corpuscular haemoglobin
mean corpuscular haemoglobin concentration
16
Q
what test is used to assess RBC morphology?
A
peripheral blood smear exam
17
Q
what parameters are directly measured by haematology analyser?
A
haemoglobin
red blood cell count
mean cell volume
18
Q
what does the mean cell volume show?
A
average size of RBC
19
Q
what can be calculated from parameters measured by haematology machine?
A
haematocrit
mean corpuscular haemoglobin
mean corpuscular haemoglobin concentration
20
Q
how can haematocrit be calculated?
A
mean cell volume x red blood cell count
21
Q
how can mean corpuscular haemoglobin be calculated?
A
Haemoglobin x 10/red blood cell count
22
Q
how can mean corpuscular haemoglobin concentration be calculated?
A
Haemoglobin / haematocrit
23
Q
what are the two types of haematology analysers?
A
flow cytometry
impedance
24
Q
how do flow cytometry haematology analysers work?
A
individual cells pass through a laser beam absorbing and scattering light. Interruptions in light count cells and light scatter is used to determine size of cell and the internal complexity. Produces differential count
25
How is cell size measured by flow cytometry?
Interruptions in light count cells
26
how is cell size and complexity measured by haematology analyser?
light scatter
27
how do impedance haematology analysers work?
individual cells pass an isotonic solution between two electrodes. Cells are poor electrical conductors so when passed between electrodes they produce a change in electrical impedance that is proportional to the size of the cell
28
what form of haematology analyser is preferable?
flow cytometry can produce a differential count
29
what are the 9 common sample artefacts which interfere with automated CBCs?
```
clots of any size
platelet clumps (may be read as a cell duce to lack of nucleus in mammalian RBC)
macroplatelets
RBC agglutination (RBC with nucleus)
nRBC
Heinz bodies
Lipaemia
leukocyte agglutination
delay in sample handling (increased haemolysis)
```
30
what is packed cell volume?
PCV: percentage of RBC in a volume of blood
31
How is PCV read?
after centrifugation, the percentage of RBC in column of the capillary tube
32
what else can be assessed during PCV test?
buffy coat assessment - number of WBC
Plasma colour
total proteins
33
what does the buffy coat on a PCV test show?
WBC and platelets, should be small
34
what does plasma colour indicate?
straw/clear = normal
bright yellow = icteric
pink = haemolysed
milky and turbid = lipaemia
35
why is a blood smear so important?
morphology changes are not picked up by any analysers
will show discrepancies/errors in any analyser (QA)
help with quick clinical decisions
PCV+Blood smear are a low cost option when no machines available
36
what are the minimum levels of patients that should have their blood smear reviewed?
all critically ill patients
| CBCs with unusual or suspicious results
37
what would indicate the need for performing a blood smear?
presence of:
nucleated RBC (indicating reduced RBC or high need for RBC)
neutrophil left shift (immature neutrophils)
unclassified or unidentified cells
automated WBC count that may not be accurate
38
what background would trigger a blood smear review?
unusual background matrix
unusual background colour
organisms or suspected organisms
39
what RBC parameters would trigger at blood smear review?
moderate to marked poikilocytosis of any kind (abnormally shaped RBC)
moderate to sever anaemias
any Heinz bodies in non-feline species (>10% in cats)
inclusions (organisms or suspected organisms)
Howell-Jolly bodies
abnormal MCV
40
what is poikilocyotsis?
strange shaped cells
41
what WBC parameters would trigger blood smear review?
```
left shift (marked or degenerative)
leukopenia
leukocytosis
lymphocytosis
unclassified cells
organisms (or suspected)
presence of granules in non-monocytes and abnormal granulation of any leukocyte
```
42
what is leukopenia?
decrease in number of WBC (<3,000 WBC)
43
what is leukocytosis?
Increase in total WBC count (>30,000 WBC)
44
what is lymphocytosis?
elevation of lymphocytes (>10,000 cells)
45
what platelet parameters would trigger blood smear review?
>900,000 platelet count
thrombocytopenia
abnormal MPV
suspected inclusions or abnormal granulation
46
what is thrombocytopenia?
low platelets (<100,000 cells)
47
what are the 3 main parts of a blood smear?
base/head
monolayer
feathered edge
48
what are the measured areas of a blood smear?
monolayer and feathered edge
49
how do RBC appear in the monolayer of the blood smear?
side by side, not overlapping
50
how should you start looking at a blood smear?
small - low magnification and at the feathered edge of the smear
51
what is the systemic approach to a blood smear exam?
start small at low magnification from the feathered end
go 2-3 fields back to the body of the smear in the monolayer
increase to oil and evaluate morphology
finish at the side, count 100 leukocytes into types looking for abnormal forms as you go
52
what do you look at regarding RBC in a blood smear?
numbers (does it loo anaemic)
do RBC look normal
is there evidence of regeneration
53
what do you look at regarding WBC in a blood smear?
number
type present
morphology
54
what do you look at regarding platelets in a blood smear?
number (estimate)
| morphology (size)
55
what is the function of RBC?
oxygen carrying to tissues
56
how do RBC appear in dogs?
central pallor taking 1/3 of cell
57
how do RBC appear in cats?
small
no central pallor
all cells same size/colour
58
what is the role of neutrophils?
defence against invading microorganisms especially bacteria
59
when do neutrophils increase?
in inflammation and infection. Stress due to adrenaline and corticosteroids
60
what do neutrophils look like under a microscope?
ribbon shaped, segmented nucleus
| pale cytoplasm
61
what do eosinophils do?
defence against parasites
| allergic response
62
what do basophils do?
defence against parasites
| allergic response as contian histemine
63
what do basophils do?
defence against parasites
| allergic response as contain histamine
64
what are granulocytes?
collective name for neutrophils, basophils and eosinophils
65
how do eosinophils and basophils differ under a microscope?
basophils are blue toned. Eosinophils have pink granules with purple nucleus
66
what are lymphocytes involved in?
immunity both adaptive/cell mediated (T cell-) and humoral (b cells - antibody production)
67
how do lymphocytes appear under a microscope?
round cells with a large round nucleus
| very little cytoplasm
68
what are monocytes?
precursor of macrophages
69
what are monocytes involved in?
phagocytosis
antigen presentation to T cells
immunomodulation
70
how do monocytes appear under a microscope?
have vacuoles
71
how do platelets appear under a microscope?
small
no nucleus
some granulation
72
what are platelets involved with?
haemostasis
formation of platelet plug
accelerating coagulation
inhibition of antithrombin III
73
in haematology what does the suffix philia or cytosis mean?
increase in number
74
in haematology what does the suffix penia mean?
decrease in number
75
what is thrombocytopenia?
reduction in number of platelets
76
what type of cells is the suffix philia used for?
granulocytes only
77
what is cytosis used for?
all other cells (apart from granulocytes)
78
in what species is the neutrophil the dominant cell type?
healthy cats, dogs, horses and camilids
79
in what species is lymphocyte the dominant cell type?
healthy cattle and rodents
80
what is WBC morphology like in rabbits and birds?
neutrophils are known as heterophils - have shiny pink granules like an eosinophil
81
in what species is the azurophil found?
reptiles and amphibions (monocyte with pinky/blue staining)
82
how do RBC appear in birds, reptiles, amphibians and fish?
nucleated
thrombocyte (platelet) is also nucleated - may look like a lymphocyte
counting is not performed by analysers due to presence of nucleus (cannot differentiate between RBC, thrombocyte or WBC)
83
what is used instead of a change in leukogram in horses, cattle and sheep?
haematology and measurement of serum acute phase proteins to detect inflammation
84
what can be diagnosed through blood smear?
```
thrombocytopenia
regenerative vs non-regenerative anemia
rouleux vs agglutination
check machine WBC differentials/ manual differential WBC count
normal and abnormal morphology
```
85
what can happen during automated counts of platelets in whole blood in EDTA?
done by analysers
commonly leads to artefactual (false) thrombocytopenia due to platelet clumping and macroplatelets
overlap in size between RBC and platelets often leads to false automated counts
86
under what circumstances should platelet numbers from blood in EDTA be checked by blood smear?
any animal with low automated counts
| every animal with clinical signs of haemorrhage
87
what do platelet estimates on blood smears assume?
no platelet clumps on feather edge
88
how is platelet estimate carried out on blood smears?
```
10 fields - oil immersion in monolayer
count number of platelets
do average
multiply by 15 or 20 (depending on practice)
estimated number x10^9/L
```
89
what can macroplatelets lead to?
false thrombocytopenia
| regeneration / increased platelet production
90
in what breed are macroplatelets normally seen?
Caviler King Charles
91
how will non-regenerative and regenerative anemia present under a microscope?
non - regenerative: bone marrow producing no new RBC so they appear normal
regenerative - many different RBC shapes
92
what do agglutination vs rouleux show?
cell interaction with each other
93
how does agglutination appear under a microscope?
bunch of grapes
large 3D clusters
interference with machine
94
how does rouleux appear under a microscope?
stack of coins
| no interference with machine
95
where is the leukogram taken from?
edge of smear within monolayer
96
what does a leukogram count?
number of WBC and the types present (in 100 cells)
97
what does anaemia reflect?
reduced oxygen carrying capacity
98
what is reduced red blood cell mass noted by?
reduced RBC
reduced haemoglobin concentration
reduced PCV and haematocrit
99
what intra-individual variables can affect RBC mass?
breeds bred for athleticism (greyhounds/thoroughbreds)
| age - young animals have reduced RBC mass until 4-6 months of age
100
what are the clinical signs of anaemia?
```
mucous membrane pallor (pale)
lethargy
exercise intollerence
tachycardia
tachypnoea
heart murmur
collapse
icterus
melaena/haematuria/haemoglobinuria
pica
```
101
what are the 3 areas anaemia is classified by?
RBC indexes
regenerative vs non-regenerative
severity of anaemia
102
what are the 3 main RBC indexes for anaemia?
macrocytic
normocytic
microcytic
103
what do macrocytic and microcytic RBC indexes mean?
macrocytic - large RBC
| microcytic - small RBC
104
what is the difference between regenerative and non-regenerative anaemia measured by?
reticulocyte counts
105
what is severity of anaemia based on?
how low haematocrit is
106
do cats or dogs compensate for anaemia better?
cats
107
what are the tests used for investigation of anaemia?
```
PCV/HCT and haemoglobin concentration
RBC indexes: MCV, MCHC/MCH
reticulocyte count
blood smear for morphology
auxiliary tests are available
```
108
what are normocytic erythrocytes?
erythrocytes of normal size
109
what are microcytic (low MCV) erythrocytes?
smaller RBC
110
what can microcytic (low MCV) erythrocytes be caused by?
iron deficiency allows an extra cell division which is usually prevented by normal haemoglobin concentration.
111
what are macrocytic (high MCV)artic RBC?
larger than normal RBC
112
what causes macrocytic RBC?
immature RBC
113
what dog breeds show naturally higher RBC?
poodles
114
what can cause artificial macrocytic RBC?
artefact in stored/old blood samples
115
what is hypochromic/ low MCHC/MCH?
presence of immature RBC (not fully haemaglobinised)
116
what is hyperchromic/high MCHC/MCH?
not physically possible (cannot fill RBC with extra haemaglobin) down to artefact
117
what would macrocytic and hypochromic results suggest?
regenerative anaemia: haemorrhage or haemolysis
118
what would normocytic and normochromic results suggest?
normal. Non- regenerative anaemia or following acute blood loss before regeneration (pre-regenerative)
119
what would microcytic and hypochromic results suggest?
iron deficiency anaemia due to chronic external blood, or secondary to liver disease, portosystemic shunt
120
what are the 2 key types of anaemia?
regenerative and non regenerative
121
what can non-regenerative anaemia be divided into?
bone marrow related
| systemic disease
122
what are the two divisions of regenerative anaemia?
haemorrhage
| haemolysis
123
what are the 2 types of haemorrhage that may cause anaemia?
internal and external
124
what are the two types of haemolysis?
intravascular
| extravascular
125
what is regeneration the bodies response to?
fall in oxygenation - kidneys release EPO
126
what is regeneration determined by in dogs and cats?
reticulocyte concentration
127
what length of time is required before there is significant blood reticulocytosis?
about 3-5 days
128
how may the regenerative response be seen in anaemia?
presence of polychromatophils (immature RBC - has lost nucleus)
129
what are reticulocytes?
precursors of RBC
130
how can reticulocytes be counted?
manually or by some of the newer haematology analysers
131
what are the 2 types of reticulocytes in cats?
aggregates
| punctate
132
what are aggregate reticulocytes?
immature reticulocytes, appear like canine reticulocytes
133
where are aggregate reticulocytes formed?
in the bone marrow in response to anaemia
134
how do aggregate reticulocytes become punctate?
mature after 12-24 hours in circulation
135
what are punctate reticulocytes?
have only small amount of reticulum (mRNA) and have undergone a degree of maturation
136
how long can punctate reticulocytes remain in the blood stream?
up to 4 weeks after the anaemia has resolved
137
describe the stages of a manual reticulocyte count
mix an equal amount of blood and vital stain
incubate at room temperature
do a normal blood smear with the mixture
evaluate 500-1000 stained RBC to determine % of reticulocytes
use % reticulocytes and RBC to determine absolute value
138
what are the two types of stain used for manual reticulocyte counts?
new methylene blue
| brilliant cresyl violet
139
how long should blood and stain be incubated for during a manual reticulocyte count?
new methylene blue - 10 mins
| brilliant cresyl violet - 15 mins
140
what are RBC evaluated for on a blood smear for anaemia?
RBC density
RBC regeneration
RBC morphology (clues as to causes of anaemia)
141
what are 4 of the most common morphological changes seen in RBC?
anisocytosis
polychromasia
hypochromasia
spherocytes/ghost cells
142
what is anisocytosis?
different cell sizes
143
what 3 questions must be asked when presented with anisocytosis?
is there macrocytosis (large RBC)
is there microcytosis (small RBC)
is there poly chromasia?
144
the presence of what red blood cell morphology in anaemic patients suggests RBC regeneration?
anisocytosis and polychromasia
145
what does polychromasia indicate?
regeneration
146
what are polychromatophils?
younger RBC - reticulocytes
147
what do polychromatophils look like?
more purple in colour - have lost nucleus
148
what is hypochromasia?
not enough haemoglobin
149
what do hypochromatic RBC look like?
larger pallor in the middle of the RBC (>1/3 of cell)
150
when is hypochromasia seen?
alongside microcytosis (reduced cell size) in iron deficiency anaemia
151
in what disease are spherocytes and ghost cells seen?
IMHA
152
what do spherocytes look like?
round, smaller and darker than RBC and have no central pallor
153
what are ghost cells formed of?
only outer RBC membrane with no internal structures
154
when are spherocytes often seen in low numbers?
concurrently with evidence of shear damage injury
155
what is polycythaemia?
increased red cell mass
156
what indicates polycythaemia?
```
increased:
haemoglobin
packed cell volume (PCV)
haematocrit (HCT)
red blood cell count (RBC)
```
157
what are the 2 types of polycythaemia?
relative
| absolute
158
what is relative polycythaemia due to?
loss of plasma volume/dehydration
159
what is relative polycythaemia known as?
erythrocytosis
160
what is absolute polycythaemia due to?
red cell mass is increased
161
what is absolute polycythaemia known as?
true polycythaemia
162
what are the clinical signs of polycythaemia?
elevated PCV (70-85%)
hyperaemic mucous membranes (dark red or blueish)
sneezing
nosebleeds
neurological signs (hyper viscosity) - seizure, blindness, ataxia, behavioral changes
163
what must be checked first in polycythaemia?
whether it is persistent or the patient is dehydrated
164
what are the 6 steps to rule out secondary causes of polycythaemia?
haematology, biochemistry and urinalysis
check reticulocyte count
assess for signs of cyanosis
check blood gas (hypoxia)
abdominal ultrasound to identify neoplasia or renal disease
thoracic rads to detect respiratory or cardiac abnormalities
165
what is increased EPO (erythropoetin) level diagnostic for?
secondary polycythaemia (can be 50x normal)
166
what is thrombocytopenia?
low platelet numbers
167
when does spontaneous haemorrhage occur?
very low platelet counts (<50x10 to the 9/L)
168
what are the clinical signs of thrombocytopenia?
```
petechiae - tiny haemorrhages
ecchymosis - bruising
melaena
epistaxis
haematuria
```
169
how can you check for true thrombocytopenia?
check the blood smear for estimate of platelets
check for clinical signs (could be due to poor collection/artefact)
repeat haematology to check for persistence if no clinical signs
170
what are additional tests for thrombocytopenia?
other haemostasis tests
testing for infectious diseases
bone marrow analysis
171
what are the common leukogram changes associated with normal or increased WBC?
```
stress leukogram
inflammatory leukogram
adrenaline (white coat) leukogram
inverted "stress" leukogram
neoplasia
```
172
what is a stress leukogram due to?
chronic disease
| exogenous steroids
173
what do you need to know when looking at inflammatory leukogram changes?
which leukocytes are increased
174
what is an inverted "stress" leukogram caused by?
Addisons disease
175
what neoplasia can be indicated by a leukogram?
leukaemias
stage V lymphoma
mast cell disease
176
describe the leukogram pattern of physiological (white coat) leukogram
increased: total WBC count, segmented neutrophils, lymphocytes
variable: monocytes
177
describe the leukogram pattern of a steroid/stress leukogram
increased: total WBC count, non-segmented neutrophils (mild), segmented neutrophils, monocytes
decreased: lymphocytes, eosinophils
(roller coaster)
178
describe the leukogram pattern of an acute inflammatory leukogram
increased: total WBC count, non-segmented neutrophils (mild), segmented neutrophils, monocytes
reduced: lymphocytes
variable: eosinophils
179
describe the leukogram pattern of a chronic inflammatory leukogram
increased: total WBC count, segmented neutrophils,
variable: non-segmented neutrophils, lymphocytes, monocytes
180
describe the leukogram pattern of a leukaemia leukogram
hugely increased total WBC count - cell types vary
181
where should WBC differential counts be taken from?
edge of monolayer
182
what is leukopenia?
no leukocytes
183
what is calculated during WBC differential counts?
percentage of different leukocyte types
184
what is neutrophilia?
increased neutrophils
185
when does neutrophilia occur?
inflammation/infection
part of stress leukogram
physiological leukogram
independent of demand due to neoplasia
186
why does neutrophilia increase with inflammation/infection?
due to cytokine release (can be seen with or without left shift or toxic change)
187
why does neutrophilia increase with physiological leukogram?
due to adrenaline release
188
what will neutrophilia be seen alongside in a physiological leukogram?
mild lymphocytosis
189
why does neutrophilia increase with stress leukogram?
due to endogenous or exogenous steroids
190
what will neutrophilia be seen alongside in a stress leukogram?
lymphopenia
monocytosis
eosinopenia
191
what neoplasia causes neutrophillia?
paraneoplastic (outside of BM)
| neoplasia of BM
192
what are signs of increased demand on neutrophils?
band neutrophil - U or S shaped nucleus with parallel sides (minimal indentation or segmentation)
signs of toxicity - Dohle bodies, foamy cytoplasm, blueish cytoplasm, toxic granules
193
what is neutrophil left shift?
release of earlier granulocyte precursors from BM
194
what does neutrophil left shift indicate?
indication of increased neutrophil demand/consumption
| inflammation/infection
195
what are neutrophil toxic changes?
in response to overwhelming demand immature neutrophils are seen. Organelles that are normally removed from the neutrophil in the BM, persist when the neutrophil is in circulation
196
what are toxic changes often seen with?
alongside left shift
197
what is seen during toxic changes?
```
cytoplasmic basophillia
Doehle bodies
cytoplasmic vacuolation
persistent primary granules (toxic granulation)
ring form nuclei
giant forms
```
198
when may neutropenia be seen in normal animals?
```
breed variations (greyhounds)
cats sit on low end of reference interval
```
199
what may lead to neutropenia?
secondary to decreased production with marrow disease/suppression
increased utilisation through marked inflammation or immune mediated destruction
200
what does complete marrow destruction or suppression cause the destruction of first?
neutrophils
201
what can marked neutropenia indicate?
predisposition to infection and sepsis
202
what is lymphocytosis?
increased lymphocyte count
203
is lymphocytosis "true" in young animals?
no as they are constantly immune stimulated
204
what can lead to lymphocytosis?
adrenaline release
mobilisation of cells (hypoadrenocorticism)
increased numbers to increased demand (immune stimulaton)
increased numbers independent of demand (lymphoproliferative disease)
205
how does normal lymphocytes appear?
around 2 RBC in size, little cytoplasm
206
how does a reactive lymphocyte appear?
lots of cytoplasm
207
how does a lymphoblast appear?
larger than 3 RBC
208
what is lymphopenia?
loss of lymphocytes
209
what can lymphopenia be caused by?
loss of chylous fluid
decreased production - viral infections, lympholytic drugs (chemo), immunodeficiency
redistribution - chronic stress, trapped in lymph nodes, lymphocytolysis, move from circulation into bone marrow and tissues
210
what is monocytosis (increased monocytes) caused by?
increased demand for macrophages - chronic inflammation, transient monocytosis
redistribution (part of stress leukogram) - increased glucocorticoid levels
increased production independent of demand - leukaemia
211
what is eosinophilia caused by?
increased demand - usually parasitism, can be allergy or inflammation of mast cell rich tissues
paraneoplastic
hypoadrenocorticism
eosinophilic leukaemia
212
is eosinopenia of clinical significance?
no
213
what leukogram findings indicate poor prognosis?
```
degenerative left shift
leukopenia
leukemoid reation
toxic neutrophils
severe or persistent lymphopenia
```
214
what is the reason for poor prognosis in degenerative left shift?
overwhelming tissue demands (exceeds BM production)
215
what is the reason for poor prognosis in leukopenia?
overwhelming tissue demands (exceeds BM production) or BM disease
216
what is the reason for poor prognosis in leukemoid reation?
excessive neutrophils due to marked inflammatory stimulus
217
what is the reason for poor prognosis in toxic neutrophils?
due to accelerated production. Associated with longer hospitalization, higher costs of treatment and increased morbility
218
what is the reason for poor prognosis in severe or persisttant lymphopenia?
indicates severe and persistent stress
