Coagulation Flashcards
From injury to a stable haemostatic plug, what are the three main components of the entire process?
- Blood vessel constriction
- Platelet aggregation
- Coagulation cascade
What factors are involved in the intrinsic pathway? What bleeding measurements assesses this pathway?
- Twelve
- Eleven
- Nine
- Eight
- Ten
APTT measures the intrinsic pathway
What factors are involved in the extrinsic pathway? What bleeding measurements assesses this pathway?
- Seven
- Five
PT measures the extrinsic pathway
What bleeding measurement assesses the final common pathway?
TT (thrombin time)
What are the phases of the coagulation pathway?
- Initiation
- Amplification
- Propagation and thrombin burst
- Stable plug formation
What are the inhibitors of the coagulation cascade?
- Tissue factor pathway inhibitor (TFPI)
- Protein C
- Protein S
- Antithrombin III
Which bleeding measurements assesses the therapy of heparin and warfarin?
- Heparin: APTT
- Warfarin: PT (INR)
What are the basic principles of bleeding disorders? How can they present?
- Vascular defects
- Platelet disorders
- Coagulation defects
- Mixed picture
Vascular defects/platelet disorders:
- Easy bleeding, into superficial skin
- Bleeding immediate after injury
Coagulation defects:
- Bleeding into deep tissues
- Delayed, severe bleeding after injury
Give examples of vascular defects
Acquired:
- Infection, steroids, senile purpura
Inherited:
- Connective tissue disorders, Osler-Weber-Rendu syndrome
Give examples of platelet disorders
Reduced platelet function
- Acquired: aspirin, uraemia
- Inherited: storage pool disease, thrombosthaenia
Reduced platelet number
- Destruction: AITP, DIC
- Reduced production: BM failure
What are the differences between acute and chronic ITP?
Acute ITP:
- Childhood (2-6 yrs)
- Preceding infection is common
- Fast onset of easy bruising
- Platelet count very low (<20,000)
- 2 to 6 weeks in duration of symptoms
- Self limiting
Chronic ITP:
- Adulthood, higher in females
- No preceding infection
- Abrupt onset of symptoms
- Platelet count low (<50,000)
- Long-term disease, associated with other autoimmune conditions
- Requires treatment: steroids, IV Ig, splenectomy)
Name and describe some inherited coagulation disorders
Haemophilia A
- Factor VIII deficiency
- X linked, 1/10,000 males
- Presents early in life with trauma or in surgery
- Increased APTT, normal PT and reduced factor VIII assay
- Severity associated with level of factor VIII deficiency
- Managed: desmopressin, factor VIII concentrations, avoid NSAIDs and IM injections
Haemophilia B
- Factor IX deficiency
- X linked, 1/50,000
- Clinically like haemophilia A
- Managed: factor IX concentrations
von Willibrand disease
- von Willibrand factor deficiency
- Autosomal dominant, 1/10,000
- Presents with bleeding (platelet or coagulation type bleeding)
- Raised APTT and bleeding time, reduced factor VIII and reduced vWF
- Managed: desmopressin, vWF and factor VIII concentrates
Name and describe some acquired coagulation disorders
Disseminated intravascular coagulation (DIC)
- Widespread activation of coagulation, consumption of clotting factors, increased risk of bleeding
- Causes: malignancy, sepsis, obstetric complications, toxins
- Low platelets, low fibrinogen, high D-Dimer, long PT/INR
- Managed: treat cause, give transfusion (FFP, platelets)
Liver disease:
- Reduced syntheses of factors, II, V, VII, IX, X, XI and fibrinogen
- Reduced absorption of vitamin K
- Abnormal platelet function
- Higher AST
Vitamin K deficiency:
- Reduced synthesis of factor II, VII, IX and X
- Reduced protein C/S synthesis
- Causes: warfarin, malabsorption, malnutrition, antibiotic therapy
- Managed: IV vitamin K, or FFP for acute haemorrhage
