Hemostasis - Ex 6

Question 1

Factors of Intrinsic Pathway (4)

Answer 1

VIII
IX
XI
XII

Question 2

Factors of Extrinsic Pathway (1)

Answer 2

VII

Question 3

Factors of Common Pathway

Answer 3

X
V
II
I

Question 4

What is the importance of Factor XIII?

Answer 4

Solidifies fibrin clot!

Question 5

Main source of Coag. Factors

Answer 5

LIVER!

*MOs: II, V, VII, X

Question 6

Factor III

Answer 6

aka Tissue Thromboplastin

*Found in fibroblasts, sm muscle cells, and endothelial cells

**Phospholipid & TF = Factor III

Question 7

Vit K dependent Factors

Answer 7

II, VII, IX, X

*Vit K activates these factors

Question 8

Main Anticoagulation protein

Answer 8

Antithrombin (70%)

This is the ONLY anticoagulant. protein we measure

Question 9

What does Antithrombin inactivate?

Answer 9

Thrombin 
XIIa
XIa
Xa
IXa

Question 10

Glomerulus and Antithrombin

Answer 10

Antithrombin can pass through glomerulus when damaged –> This decreases antithrombin levels –> patient is now more susceptible to Thrombosis

Question 11

Fibrinolysis

Answer 11

Conversion of plasminogen to plasmin by:

Factor XII and tPA

Question 12

Tissue plasminogen activator - therapy

Answer 12

Used clinically for strokes

• tPA will artificially force clot breakdown

Question 13

Fibrinolysis - Simplified

Answer 13

Plasmin breaks down fibrin or fibrinogen into:

1. D-Dimers
   * *Fibrin only
2. Fibrin(ogen) Degradation Products (FDPs)

Question 14

Thrombocytopenia - Differentials (3)

Answer 14

1. Destruction (most common)
2. Consumption
3. Decreased production

Question 15

Thrombocytopenia

Answer 15

Disorder of primary hemostasis –> see petechia on mucosal surfaces and membranes

Question 16

DIC

Answer 16

Cause of thrombocytopenia - consumption

1. Massive activation of clotting factors
2. Rapid consumption of clotting factors –> leads to bleeding
   * *Clotting to death and bleeding to death at the same time**

*DIC is a red flag for a severe underlying disorder –> it is never a primary disorder

Question 17

DIC - Causes

Answer 17

• Extensive Tissue Damage
• heat stroke
• pancreatitis
• severe hypoxia
• Endotoxemia/Septicemia
• IMHA
• Neoplasia (procoagulant proteins)
• Vascular disease

Question 18

Easiest way to remember DIC? (Lab Values)

Answer 18

EVERYTHING is abnormal!

Question 19

Liver failure

Answer 19

Liver is source of clotting factors –> damaged liver –> decreased production of factors –> coagulopathy

Question 20

Bile Duct Obstruction

Answer 20

Bile is required to absorb fat –> Via K is fat solute –> without fat, there is a Vit K deficiency that can reduce coagulation factor activity

Question 21

Name 7 Lab Evaluations of Hemostasis

Answer 21

1. Platelet count
2. Bleeding time
3. Activated clotting time (ACT)
4. Activated partial thromboplastin time (APTT)
5. One-stage prothrombin time (OSPT or PT)
6. Fibrinogen (Thrombin Time)
7. von Willebrand factor (vWDF)

Question 22

Platelet count

Answer 22

Estimation from a blood film

Automated

Question 23

Bleeding Time

Answer 23

Cut buccal mucosa and see how long it takes to clot

Question 24

Tests of Intrinsic Pathway

Answer 24

APTT and ACT

Question 25

Tests of Extrinsic Pathway

Answer 25

OSPT (aka PT)

Question 26

Which of the tests uses whole blood?

Answer 26

ACT

*Thrombocytopenia can cause erroneously prolonged clotting times

Question 27

Quantitative Fibrinogen

Answer 27

Measure of fibrinogen

1. Excess thrombin is added to diluted plasma
2. Rate of fibrinogen to fibrin is measured
3. Time to “clot” is indirectly proportional to fibrinogen concentration

Question 28

How do we measure fibrinolysis?

Answer 28

D-Dimers