clinical haematology 1

Question 1

What is haematology

Answer 1

(complete blood count aka CBC) is study of blood and it’s an important part of diagnostic investigation of any disease process mainly related with blood

Question 2

EDTA blood tube

Answer 2

chelates (binds) calcium in blood-required for blood clotting

• Heparin can be used in some exotic species
• Respect amount of blood require in tube-because if over/under fill it can affect the results and create artefacts

Question 3

EDTA blood tube steps

Answer 3

1) Gently invert tube 10-20 times to mix well
2) Prepare 2 fresh blood smears
3) Fully and quickly dry the smears
4) Don’t store in slide containers before dry

Question 4

Storage

Answer 4

• Store in fridge until sent off to lab/running sample
• DON’T FREEZE-ruptures the cells
• Don’t refrigerate smears-condenses the cells and leads to water artefacts
• Store in slide containers

Question 5

Philia OR Cytosis

Answer 5

INCREASE
E.g. neutrophilia or erythrocytosis
=mean increased cell counts

We use philia for granulocytes only:
•Neutrophils •Eosinophils •Basophils

Other cells we use cytosis
E.g. erythrocytosis, thrombocytosis,lymphocytosis, monocytosis

Question 6

Penia

Answer 6

DECREASE
E.g. thrombocytopenia or lymphopenia
Exception- anaemia

Question 7

Erythrocytes/RBC

Answer 7

· Produced mainly in the bone marrow - Takes approx. 5 days to make reticulocytes
·Extramedullary haematopoiesis may occur in cases of increased demand (several organs, spleen most common)
· Variable half-life
- 110 days (dog)
- 70 days (cat)
- 160 days (cattle)
- 145 days (horse)
· End of life: senescent RBC removed in spleen or haemolysis

Question 8

Parameter generated by analyser

Answer 8

Bold means directly measured by analyser
· Haemoglobin (Hb) (uses a biochemical method)
· Haematocrit (HCT)
· calculated from those measured (HCT = MCV x RBC)
· Red blood cell count (RBC)
· Mean cell volume (MCV): average size of RBCs
· Mean corpuscular haemoglobin (MCH)
· calculated (MCH = Hbx10 / RBC)
· Mean corpuscular haemoglobin concentration (MCHC)
calculated (MCHC=Hb/HCT)

Question 9

Common sample artefacts

Answer 9

Always do fresh blood smear
· Clots
· Platelet clumps
·Macroplatelets
· RBC agglutination
· nRBC
· Heiz bodies
· Lipemia
· Leukocyte agglutination
· Delay in sample handling (increase in MCV, haemolysis, etc)

Question 10

Packed cell volume (PCV)

Answer 10

More reliable way of measuring blood cell mass
· PCV - % of red cells in a volume of blood. Manual technique
· Centrifuged whole blood, red cells read as a % of column
· Buffy coat assessment
· Plasma
· Total proteins measurement
· DIFFERENT TO HEMATOCRIT

Question 11

Asses colour of plasma

Answer 11

clear/pale straw-normal
bright yellow-icteric
pink-haemolysed
milky and turbid-lipaemia

Question 12

Blood smear examination

Answer 12

Should look at the blood smear because:
· Morphology changes are not seen in automated analysers
· CBCs with unusual or suspicious results (QA)
· Quick clinical decision-espc in critical patients
· PCV + blood smear=low cost
· Useful when no machines available

Question 13

LOW POWER (10x objective)

Answer 13

Examine the FEATHERED EDGE to check for platelet clumps.

Question 14

HIGH POWER (100x objective)

Answer 14

· The blood cells must only be examined in the MONOLAYER - red blood cells, white blood cells and platelets.
· 100x objective requires immersion oil.

Question 15

normal RBC

Answer 15

Function-oxygen carrying to tissues
· Number (anaemic?)
· Morphology (shape, size, colour)
· Regeneration?

Question 16

WBC

Answer 16

· Number
· Type present
· Morphology

Question 17

Leukocytes-neutrophils

Answer 17

function-defence against invading microorganisms especially bacteria
-increased in inflammation and infections
increased with stress (adrenaline and corticosteroids)

Question 18

Leukocytes-lymphocytes

Answer 18

function-cell mediated immunity-cytotoxic T cells, helper T cells
-Humoral immunity-B cells antibody production

Question 19

Normal Lymphocytes

Answer 19

• Some are responsible for attacking bacteria and viruses.
• Other target the body’s own cells that are not functioning properly due to a virus or cancer.
• Having too many or too few can be a sign of disease.

Question 20

reactive lymphocyte

Answer 20

• immune-stimulated with upregulated synthesis of inflammatory mediators, and/or immunoglobulins (antibodies), or both.
• In peripheral blood suggest active, systemic antigenic stimulation secondary to both infectious and noninfectious disorders.

Question 21

Lymphoblasts

Answer 21

Immature white blood cell that gives rise to a type of immune cell known as a lymphocyte.

Question 22

Leukocytes-eosinophils and basophils

Answer 22

eosinophils:
-defence against parasites
-allergic response
basophils:
-defence again parasites
-allergic response (contain histamine)

Question 23

leukpcytes-monocytes

Answer 23

• phagocytosis
• antigen presentation to T cells
• immunomodulation
• precursors to macrophages

Question 24

Platelets

Answer 24

· Clumps
· Number-smear estimate
· Morphology (size)
-homeostasis
-formation of platelets plug
-accelerating coagulation
-inhibits antithrombin III

Question 25

Species differences

Answer 25

· Neutrophil is the dominant cell type
- in healthy cats, dogs, horses, camelids
· Lymphocyte is the dominant cell type
- In healthy cattle, rodents
· Some species have VERY different WBC morphology
- the rabbit neutrophil (or heterophil) has shiny pink granules like an eosinophil
· Reptiles and amphibians have a whole other cell type
- the azurophil = is like a monocyte but more pinky-blue staining

Question 26

Birds, reptiles, amphibians, fish

Answer 26

· RBCs are nucleated
· The platelet equivalent (thrombocyte) is nucleated, too - can look like a lymphocyte.
· Counting cannot be performed by analysers
· RBCs, thrombocytes cannot be distinguished from WBCs