Inherited and acquired bleeding disorders (haematology) Flashcards
What causes bleeding disorders? (4)
Vascular disorders
Platelets disorders
Von willebrand factor disorders
Defective coagulation
What do …. deficiency mean?
1. Quantitative
2. Qualitative
- Not enough platelets, clotting factors etc.
- There are platelets, clotting factors etc but they are not working (have a defect).
What are the vascular bleeding disorders we have? (2)
•Inherited
-Hereditary haemorrhagic telangiectasia
-Connective tissue disorders
•Acquired
-Senile purpura
-Steroid purpura
-Scurvy
What are the causes of thrombocytopenia? (5)
Inherited
-Failure of platelet production.
Acquired
-Failure of platelet production.
-Sequestration
-Dilution
-Increase in platelet destruction.
What are the disorders of platelet function? (7)
•Hereditary
-Bernard-soulier syndrome
-Storage pool diseases
-Thrombasthena
•Acquired
-Antiplatelet drugs
-Hyperglobulinaemia
-Uraemia
-Myeloproliferative amd myelodysplastic disorders.
What are the hereditary coagulation disorders we have? (4)
-Factor VIII deficiency (haemophilia A)
-Factor IX deficiency (haemophilia b)
-Von willebrand disease
-Deficiencies of other coagulation factors.
What are the acquired coagulation disorders? (5)
-Massive transfusion syndrome
-Deficiency of Vit-K dependent clotting factors (2,7,9,10)
-Liver disease
-Disseminated intravascular coagulation.
-Coagulation caused by antibodies.
What is the diagnostic approach towards bleeding disorders? (4)
-Take family history.
-Physical examination
-Laboratory screening
-Confirmatory testing
Why is calcium removed when the blood lab test is done?
To prevent clotting of the blood.
What is Prothrombin Time (PT) ?
It is the time required for fibrin clot to form after the addition of thromboplastin to citrated platelet poor plasma.
What is the normal range for PT?
10-14 seconds
What does the PT test results indicate when they are:
1. Isolated prolonged
2. Shortened
3. Also aPTT is prolonged
- Factor VII deficiency
- Vitamin K supplementation, Fresh frozen plasma transfusion.
- Vitamin K deficiency, Vitamin K antagonists, liver disease, Direct thrombin inhibitors, Factor V and VIII deficiency, afibrinogenaemia or dysfibrinogenaemia.
What is Activated Partial Thromboplastin Time (aPTT)?
It is the time required for a fibrin clot to form after the addition of contact activator, phospholipid and calcium in citrated platelet poor plasma.
What is the normal range of aPTT?
25-38 seconds
Which clotting factors are vitamin K dependent?
II, VII, IX and X.
What does the aPTT test results indicate, when they are:
1. Shortened
2. Prolonged (3)
- Elevated factor VIII activity.
- Deficiency in factor II, V, VIII, IX, X and XII (any).
Non-specific inhibitors
Specific coagulation factor inhibitors .
What is Thrombin Time (TT)?
It is the time required for a fibrin clot to form after the addition of thrombin to citrated platelet poor plasma.
Normal range for TT?
15-19 seconds
What does the TT results indicate if they are:
1. Shortened
2. Prolonged (6)
- Coagulation activation
- Hypoalbuminaemia
Hypofibrogenaemia
Increased concentration of fibrin degradation products.
Dysfibrogenaemia
Thrombin inhibitors
Paraproteinaemia
Which test should be performed after aPTT and/or PT were prolonged, and does that test help us with? (3)
-Perform mixing or correction assay, it helps to determine where the prolonged clotting times are due to:
-Circulating inhibitors of coagulation factors.
-Clotting factor deficiency
How do we know whether the problem is with factor deficiency or inhibitors?
If the clotting time normalize, it is a factor deficiency, if it remains prolonged it is inhibitors.
What are the confirmatory tests that are done after the mixing studies? (2)
-In a case of a factor deficiency, factor assay is performed to measure the specific factor activity.
-In a case of inhibitor a factor assay is done to measure the specific factor activity and inhibitor assay to measure the concentrations of the inhibitor of the deficient coagulation factor and/or lupus anticoagulant.
