Acquired Disorders of Haemostasis (Haematology Pathology)

Question 1

What are the causes of acquired bleeding disorders?

Answer 1

1) Vit K deficienct
2) Liver Disease
3) Massive transfusion syndrome
4) Disseminated Intravascular Coagulation
5) Iatrogenic
6) Acquired Inhibitors

Question 2

How do we know whether a prolonged APTT is due to deficiency of a clotting factor or due to inhibition of the factor by an enzyme of antibody?

Answer 2

The APTT is repeated with 50:50 mix patient to normal plasma.
1) If there is a deficiency of clotting factor then APTT will become normal due to addtion of normal plasma.

2) If it is caused by inhibition of clotting factor then APTT will remain abnormal as inhibitory protein will cancel out the effect of added clotting factor from normal plasma.

Question 3

Why is platelet count low in advanced liver disease?

Answer 3

1) Liver disease caused portal hypertension.
2) Portal hypertension causes congestion in the spleen.
3) The spleen is where platelets are formed. congestion means the platelets cannot leave the spleen.

Question 4

Name the Vitamin K dependant clotting factors.

Answer 4

Factor 2 , 7, 9, 10

Question 5

Where are the clotting factors produced?

Answer 5

Liver.

All are produced in the hepatocytes. Exept F8 which is produced in the Kupffer cells of the liver.

Question 6

Describe the role of Vitamin K in the production of clotting factors 2, 7, 9, 10

Answer 6

Vitamin K acts as a cofactor for the production of F2,7,9,10.
After the clotting factors have been synthesised in the hepatocytes of the liver. Vit K modifies them by adding on a compound which activates them for use in the clotting cascade.

Question 7

How does warafin work?

Answer 7

Warfarin is an anitcoagulant.
It works by inhibiting the conversion of Vitamin K epoxide into Vitamin K (reduced). Therefor clotting factors 2, 7, 9 and 10 cannot be modified for use in the clotting cascade.

Question 8

What are the causes of Vitamin K deficiency?

Answer 8

1) Obstructive Jaundice:
- Vit K is fat soluble, so needs lipids to be absorbed from the gut. This requires bile salts. A gall stone can prevent the secretion of bile and cause jaundice.

2) Prolonged nutritional Deficiency
- Vit K can be stored for a long time. So nutritional defiency needs to be prolonged to use up stores.

3) Broad spectrum antibiotics.:
VIt K is produced by gut flora. Broad spec antibiotics kills these bacteria.

Question 9

How does liver disease cause clotting disorders?

Answer 9

• clotting factors are produced in the liver. Cirrhosis damages hepatocytes so they cannot be produced.&raquo_space;>Reduced plasma conc of clotting factors.
• Thrombocytonpenia (low platelets) caused by portal hypertension&raquo_space;> congestion in spleen.
• Alcohol usually cause of liver disease. Alcohol is toxic for bone marrow&raquo_space;> no platelets produced.

Question 10

What is Disseminated intravascular coagulation?

Answer 10

widespread activation of the clotting cascade that results in clotting in the small vessels. This lead to compromised blood flow and organ damage.

Question 11

What are the causes of disseminated intravascular coagulation?

Answer 11

1) Sepsis:
Tissue damage releases tissue factor which activates the coagulation cascade.

2) Obstretric complications:
Placental damage releases tissue factor

3)Hamolysis due to incompatible blood transfusion