Clinical Approach to Bleeding

Question 1

aPTT

Answer 1

APTT measures intrinsic pathway of coagulation which includes factors XII, XI, IX, VIII, X, V, II and I; any deficiency, inhibitor or dysfunctional molecule will cause its prolongation.

Question 2

Thrombin Time

Answer 2

THROMBIN TIME measures the conversion of fibrinogen to fibrin after the addition of thrombin; any deficiency, inhibitor or dysfunctional molecule of fibrinogen may prolong it. Also heparin inhibits thrombin and prolongs thrombin time.

Question 3

Mixing Assay

Answer 3

APTT done on patient plasma mixed with normal plasma to determine if an inhibitor is present. Failure of a previously long APTT to correct after mixing indicates inhibition

Question 4

Type I vW Disease

Answer 4

This is the most common abnormality. Individuals have a mild to moderate decrease in plasma von Willebrand’s factor.

Question 5

Type II vW Disease

Answer 5

This is much less common. In these cases there are normal or near normal levels of protein–but there are qualitative abnormalities. There are a number of subtypes of type II disease.

Question 6

Type III vW Disease

Answer 6

These individuals may be either a double heterozygote, or homozygous for a single defect in von Willebrand’s factor. These patients have severe mucosal bleeding, no detectable von Willebrand’s factor antigen or activity, and may have very little factor VIII.

Question 7

What are some causes of quantitative platelet disorders?

Answer 7

ITP
Pregnancy
TTP
HIV
Microangiopathic Thrombocytopenia
DIC
Lupus

Question 8

What are some signs of coagulopathy due to liver disease?

Answer 8

• Can manifest with increased PT/INR
• The liver also produces inhibitors of coagulation such as anti-thrombin three and protein C and S. and is the clearance site for activated coagulation factors and fibrinolytic enzymes. The, patients with liver disease are also hypercoagulable and predisposed to developing DIC or systemic fibrinolysis.