Chapter 24: Coagulation disorders

Question 1

What are the most common disorders involving coagulation factors?

Answer 1

(1) Hemophilia A (factor VIII)
(2) Hemophilia B (Factor IX)
(3) vWD

Question 2

What is the epidemiology of Hemophilia A?

Answer 2

30-100 out of a million. The disorder is sex linked however up to one third of the cases are due to spontaneous mutations.

Question 3

What is the cause of Hemophilia A?

Answer 3

Defective or deficient factor VIII.

Question 4

What are the clinical features/presenting symptoms of hemophilia A?

Answer 4

Hemophilia A causes excessive bruising and bleeding along with hemarthroses and hematomas.

Question 5

What are hemophilic pseudotumors?

Answer 5

Large encapsulated hematomas with progressive cystic swelling.

Question 6

Why did a large proportion of hemophiliacs become HIV positive?

Answer 6

Before the blood testing hemophiliacs would contract HIV from the many blood transfusions they would receive. (HCV as well)

Question 7

What are the abnormal lab values associated with hemophilia A?

Answer 7

(1) abnormal activated partial thromboplastin time
(2) Abnormal Factor VIII clotting assay.
(3) Bleeding time and prothrombin time are normal.

Question 8

How is hemophilia A treated?

Answer 8

(1) Factor VIII replacement (for bleeding episodes)

2) Desmopressin (DDAVP) stimulates endothelial cells to release Factor VIII. can be used for milder hemophilias

Question 9

What prophylactic measures can be undertaken in the treatment of Hemophilia A?

Answer 9

Factor VIII infusion three times a week and avoidance of rough physical contact can limit the occurance of bleeding episodes.

Question 10

What levels of Factor VIII or IX are necessary to avoid most of the mortality and morbidity?

Answer 10

Factor VIII or IX levels above 1% are usually high enough to avoid morbidity.

Question 11

What is one of the most serious complications of factor VIII therapy?

Answer 11

Some patients develop antibodies against factor VIII.

Question 12

What differentiates factor VIII deficiency from factor IX deficiency?

Answer 12

The only difference is the specific clotting assay that used to identify it. Hemophilia B is less common.

Question 13

What lab findings dare associated with Hemophilia B?

Answer 13

(1) Abnormal APTT

(2) Factor IX clotting assay.

Question 14

What is the normal role of vWF?

Answer 14

vWF facilitates platelet adherence to the ECM and it binds factor VIII.

Question 15

What is the most common inherited bleeding disorder?

Answer 15

von Willebrand Disease. Autosomal dominant

Question 16

What lab findings are associated with vWD?

Answer 16

(1) prolonged bleeding time
(2) Low factor VIII levels
(3) prolonged APTT
(4) Low vWF
(5) Defective platelet aggregation with ristocetin.
(6) collagen binding function is usually reduced.

Question 17

How is vWD treated?

Answer 17

(1) antifibrinolytic agents (tranexamic acid)
(2) desmopressin (DDAVP)( Type 1 vWD)
(3) vWF and factor VIII concentrates

Question 18

From where is vitamin K absorbed?

Answer 18

Vegetables and bacterial synthesis in the gut.

Question 19

what conditions can cause a vitamin K deficiency?

Answer 19

malabsorption, inadequate diet, and inhibition of vit K by drugs.

Question 20

What clotting factors are dependent on vitamin K?

Answer 20

Factors II, VII, IX, X, C, And S.

Question 21

What is the role of Vit K as a cofactor?

Answer 21

Vitamin K converts PIVKA into the proper clotting factors.

Question 22

How does warfarin inhibit clotting?

Answer 22

Warfarin inhibits the reduction of vitamin K back into its active form after it has preformed its function. This leads to a functional vitamin K deficiency.

Question 23

What is hemorrhagic disease of the newborn?

Answer 23

Newborns are usually deficient in vitamin K this leads to bleeding.

Question 24

How is hemorrhagic disease of the newborn diagnosed?

Answer 24

Most findings are normal except for excessive bleeding and absent fibrin degradation products.

Question 25

How is hemorrhagic disease of the newborn treated?

Answer 25

Vitamin K is given IM to all newborn infants as a prophylactic treatment. More can be added if hemorrhage occurs.

Question 26

What can cause Vitamin K deficiency?

Answer 26

(1) obstructive jaundice
(2) Pancreatic disease
(3) Small bowl disease

Question 27

How is vitamin K deficiency diagnosed?

Answer 27

(1) prolonged PT
(2) prolonged APTT
(3) Low Factor II, VII, IX, and X

Question 28

How is vitamin K deficiency treated?

Answer 28

With prophylactic vitamin K supplements. If bleeding has already occured IV vit K can correct deficiency within 6h.

Question 29

Disease in which organ often leads to bleeding tendency?

Answer 29

Liver disease of various kinds leads to a bleeding tendency.

Question 30

What is the key event underlying DIC?

Answer 30

Increased activity of tissue factor

Question 31

What conditions can trigger DIC?

Answer 31

(1) entry of procoagulant material into the circulation

(2) Widespread endothelial damage and collagen exposure.

Question 32

What are the clinical features of DIC?

Answer 32

(1) excessive bleeding

(2) Microthrombotic complications.

Question 33

What laboratory findings are associated with DIC?

Answer 33

(1) low platelets
(2) Low fibrinogen
(3) prolonged thrombin time
(4) High fibrin degradation products
(5) Prolonged PT and APTT

Question 34

What histological findings are associated with DIC?

Answer 34

Microangiopathic hemolysis.

Question 35

How is DIC treated?

Answer 35

(1) Supportive therapy with FFP or cryoprecipitate
(2) Heparin or antiplatelet drugs to stop the consumption of clotting factors.
(3) Recombinant protein C.

Question 36

How is massive transfusion syndrome managed?

Answer 36

By platelet transfusion and clotting factor replacement.

Question 37

What is thromboelastography?

Answer 37

Thromboelastography is a method of measuring hemostatic function in real time. This is useful in surgery associated with bleeding disorders.