lecture 8 - tests of haemostasis & bleeding disorders

Question 1

What deficiencies would lead to a prolonged prothrombin time?

Answer 1

FVII, FX, FV (involved in the intrinsic and subsequent common pathways)

Question 2

What deficiencies would lead to a prolonged Activated partial thromboplastin time?

Answer 2

FXII, FXI, FIX, FVIII, FX, FV

Question 3

Which factor deficiency is of little clinical importance?

Answer 3

FXII

Question 4

What factors are important to ask/consider when taking a history for a possible bleeding disorder?

Answer 4

Location of bleeding (mucosa, joints, skin), pattern of bleeding (frequency/severity), drug history, diet, family history

Question 5

What pattern of inheritance do Haemophilias have?

Answer 5

X-linked recessive

Question 6

Which sex will be affected by Haemophilia, and which will be carriers?

Answer 6

X-linked recessive - only males are affected, females are carriers

Question 7

What are the 2 types of Haemophilia?

Answer 7

A & B

Question 8

What Factor is affected in Haemophilia A?

Answer 8

FVIII

Question 9

What factor is affected in Haemophilia B?

Answer 9

FIX

Question 10

What is the treatment for Haemophilia?

Answer 10

IV infusion of the deficient factor (FVIII for A, FIX for B)

Question 11

Which pathway in the coagulation cascade is affected by Haemophilia A?

Answer 11

Intrinsic Pathway (FVIII)

Question 12

Which pathway in the coagulation cascade is affected by Haemophilia B?

Answer 12

Intrinsic Pathway (FIX)

Question 13

What changes will be observed to platelet count in patients with Haemophilia?

Answer 13

None - platelets unaffected in both types

Question 14

Why is prothrombin time normal in patients wit Haemophilia?

Answer 14

PT time measures extrinsic pathway, which is unaffected by Haemophilia

Question 15

What are the lab findings in haemophilia A?

Answer 15

Prolonged APTT, decreased FVIII levels,
but, normal platelets, normal PT

Question 16

What are the lab findings in haemophilia B?

Answer 16

Prolonged APTT, decreased factor IX levels,
but, normal platelets and normal PT

Question 17

What are the common causes of Vitamin K deficiency?

Answer 17

Antibiotic use (gut bacteria make vit K), bowel malabsorption, neonates/premature infants, low dietary intake

Question 18

What will be the key laboratory test findings in Vitamin K deficiency?

Answer 18

Increased APTT AND increased PT - because factors in both intrinsic and extrinsic pathways affected

Question 19

What is DIC (disseminated intravascular coagulation)?

Answer 19

A thrombohaemorragic disorder characterised by over activation of the coagulation cascade and platelets due to vessel damage, followed by the consumption of clotting factors and platelets resulting in bleeding.