Clinical Haematology

Question 1

What is the principle of automated counts?

Answer 1

Anti-coagulated blood is mixed and sampled then sent to various chambers for analysis:

• RBCs use light scatter
• Haemoglobin measured after lysis

Question 2

What pieces of informartion is produced onto a full blood count that can be used to diagnose haematological abnormalities?

Answer 2

WBC and differntial count
RBC
Platelet count

Question 3

Describe a quantitiave and morphological feature of a type of white blood cell.

Answer 3

When recognizing the different cell types you can correlate them with diffeent types of infections. (E.g. basophils are risen, present, and classed with infection/malignancy)

Question 4

Describe a quantitiave and morphological feature of a type of red blood cell.

Answer 4

When recognizing the different cell types you can correlate them with diffeent types of infections. (E.g. when RBC number is decreased it can indicate bleeding/haemolysis)

Question 5

What causes a low platelet count?

Answer 5

Pregnancy, infection, clotting disorders

Question 6

What causes high platelet count?

Answer 6

Myeloproliferative disorders

Question 7

How may abnormal blood counts/morphology be investigated further?

Answer 7

Bone marrow biopsy via needle aspirate

Question 8

Name a bloodborne parasite.

Answer 8

Malaria; plasmodium falciparum

Question 9

How is malaria tested for?

Answer 9

Using an antigenic malaria test.

Question 10

What is haemoglobinopathy?

Answer 10

Haemoglobinopathy refers to an inherited qualitative (Sickle cell) or quantitative (Thalassaemias) defects in globin chain synthesis.

Question 11

How is haemoglobinopathy diagnosed?

Answer 11

Diagnosis starts with a full blood count and questionnaire for further specific testing. Gel electrophoresis can further differntiate abnormal haemoglobins by seperation according to their charge at specific pH.

Question 12

What happens when there is a problem with haemostasis?

Answer 12

Coagulation

Question 13

How does coagulation manifest?

Answer 13

Typically manifests as spontaneous bruising (due to no apparent trauma), thus bleeding into a muscle i.e. a haematoma.

Question 14

What is primary haemostasis?

Answer 14

Its the intial response pf the body to vascular injury via formation of a platelet plug, reinforced by fibrin strands, to stop the bleeding.

Question 15

What does the coagulation cascade entail?

Answer 15

the coagulation cascade has 3 pathways: Intrinsic, extrinsic, and common leading to fibrin formation. The pathways are a series of reactions, in which the inactive precursor of an enzyme, are activated to become active components which then catalyze the next reaction, ultimatley resulting in cross-linked fibrin.

Question 16

What is fibrinolysis?

Answer 16

Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. In fibrinolysis, the fibrin clot, the product of coagulation, is broken down.

Question 17

How are lab analysis results protrayed in terms of haematology?

Answer 17

Concentartion is often not measured but rather looking at what is present in the specimen as a persentage or ‘a percentage of normal’ as a unit of measure.

Question 18

Describe 3 routine coagulation screening tests.

Answer 18

Clotting screen;
PT: investigates extrinsic pathway
APTT: investigates intrinsic pathway
These 2 tests together will detect abnormalities of the coagulation cascade.

Fibrinogen; this is formed at the end of the clotting process.
Low fibrinogen can be found in liver disease.
High fibrinogen can be found in infection.

D-dimer; is the protein fragment that is found after blood clot degraded by fibrinolysis.
High d-dimer is also found in infection.

Question 19

How is anticoagulation therapy done?

Answer 19

The most commonly used anticoagulant therapy is Warfarin.

Question 20

What are the advantges and disadvantages of Warfarin?

Answer 20

ADV; cheap

DISADV; interferance with other drugs (e.g. antibiotics) and vitamin K rich foods.

Question 21

What alternative drugs may be used for anticoagulation?

Answer 21

Dabigatran & Rivaroxaban

Question 22

What are the advantages and disadvantages of alternative anticoagulant drugs?

Answer 22

ADV; monitoring unrequired, short half-life, drugs and food don’t interact
DISADV; expensive, no antidote, cannot monitor

Question 23

How does Warfarin work?

Answer 23

It inhibits the synthesis of vitamin K dependant factors in the liver.

Question 24

How does fibrinolysis work?

Answer 24

Plasmin is the enzyme that cuts the fibrin mesh leading to the production of circulating fragments.

Question 25

How does a stago coagulation analyser work?