Haemostasis

Question 1

what is haemostasis

Answer 1

Haemostasis: blood (haem) stop/stand still (stasis)
The haemostasis is strictly controlled

Question 2

what are the 5 major components of the haemostatic system?

Answer 2

1. Blood vessels
2. Platelets
3. Coagulation factors
4. Coagulation inhibitors
5. Fibrinolysis

Question 3

what is primary haemostasis?

Answer 3

1. Platelets respond to the vessel wall
   injury
2. Platelets adhere to the vessel wall
3. A primary platelet plug is formed

Question 4

what is secondary haemostasis?

Answer 4

1. Activation of the intrinsic and
   extrinsic coagulation pathways
2. Activation of the common pathway
3. Fibrin strand formation and
   strengthening of the platelet plug

Question 5

describe Blood Vessels in Haemostasis

Answer 5

Question 6

describe Von Willebrand Factor (vWF)

Answer 6

Question 7

discuss characteristics of Platelets

Answer 7

Question 8

describe platelet storage granules

Answer 8

Question 9

describe the primary haemostasis process

Answer 9

Question 10

what are the results of primary haemostasis?

Answer 10

Primary haemostasis forms a temporary and weak platelet plug

Unstable and needs strengthening

secondary haemostasis

Question 11

what is the need for secondary haemostasis?

Answer 11

A weak platelet plug needs strengthening by coagulation
factors (secondary haemostasis)

Question 12

what is secondary haemostasis strengthened by

Answer 12

Coagulation factors are mostly proenzymes (zymogens)

Question 13

where are most coagulation factors synthesised?

Answer 13

liver

Question 14

what do proenzymes require to carry out their function

Answer 14

Proenzymes require activation to carry out their function
* Active form of a coagulation factor is denoted ‘a’

Question 15

what are the four stages of haemostasis?

Answer 15

Question 16

Explain the Coagulation Cascade

Answer 16

Question 17

explain the extrinsic pathway

Answer 17

Question 18

explain the intrinsic pathway

Answer 18

Question 19

explain the common pathway

Answer 19

Question 20

What happens to the clot afterwards?

Answer 20

Question 21

Why do we not get clots all the time?

Answer 21

Question 22

Why do we not get clots all the time?

Answer 22

Question 23

When to get tested?

Answer 23

• Unexplained or excessive bruising or prolonged bleeding,
  either spontaneously or from injuries or surgery.
• For women and girls who experience very heavy periods.
• Relative with a known hereditary coagulation factor deficiency.
• To follow up treatments after receiving a diagnosis to see that
  your treatment is working.
• Other medical conditions that affect coagulation factors.
• As part of investigations for Thrombophilia (increased clotting).

Question 24

Tests used to evaluate clotting and bleeding

Answer 24

• Standard tests
• Full blood count (FBC)
• Blood film
• Coagulation tests
• PT, APTT and TT
• Analysis of clotting inhibitors like Protein C and Protein S
• Platelet function tests
• PFA-100 and lumi-aggregometry
• Flow cytometry for receptor expression
• A test to rule out blood clots in the body
• D-dimer

Question 25

what are the Specimen Requirement?

Answer 25

Question 26

Laboratory Diagnosis

Answer 26

Question 27

Prothrombin Time (PT)

Answer 27

Question 28

Activated Partial Thromboplastin Time (APTT)

Answer 28

Question 29

Thrombin Time (TT

Answer 29

Question 30

fibrinogen quantification

Answer 30

Fibrinogen quantification is a laboratory test that measures the amount of fibrinogen in the blood. Fibrinogen is a protein that is essential for blood clotting. The normal fibrinogen levels for an adult range between 200 and 400 milligrams/deciliter. The test measures fibrinogen levels as grams per litre. A typical fibrinogen level is between 4 grams per litre or 200 to 400 milligrams per deciliter. The Clauss assay is a functional test that measures the time taken for plasma to clot in a high concentration of thrombin, with a comparison against a reference plasma calibration curve. It is the gold standard for fibrinogen quantification

Question 31

vWF test

Question 32

Measuring Protein C

Answer 32

Question 33

Measuring Protein S

Answer 33

Question 34

Measuring platelet function

Answer 34

Question 35

Flow cytometry

Answer 35

Question 36

Summary: Laboratory Tests

Answer 36

* The coagulation cascade can be evaluated with multiple tests: * PT – extrinsic and common pathway * APTT – intrinsic and common pathway * TT – functional fibrinogen * Protein C and Protein S – Protein deficiency that leads to blood clots * Platelet function can be measured using lumi-aggregometry or the PFA-100. * Flow cytometry is a good complement to investigate receptor levels

Question 37

treatments

Answer 37

Aspirin * Warfarin * Heparin * Purinergic receptor inhibitors

Question 38

Aspirin (acetylsalicylic acid)

Answer 38

Question 39

Heparin

Answer 39

Question 40

Purinergic receptor inhibitors

Answer 40

Question 41

Warfarin

Answer 41