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Coagulation Profile

Protocols

Intrinsic pathway

The intrinsic pathway is activated by contact with a damaged surface and goes as follows:

Factor XII → Factor XI → Factor IX (+ Factor VIII + vWF) → Common pathway

Extrinsic pathway

The extrinsic pathway is activated by the release of tissue factors and goes as follows:

Factor VII → Common pathway

Combined pathway

The combined pathway then proceeds the intrinsic/extrinsic pathways and goes as follows:

Factor X (+ Factor V) → Factor II → Factor I (+ Factor XIII → Fibrin mesh)

The diagram below should help put all of this into context.

NORMAL Level;

26-36 sec


CAUSES Increase APTT

  1. Lupus anti-coagulant (antiphospholipid syndrome)
  2. Heparin exposure
  3. Haemophilia A and B (Factor VIII and IX deficiency respectively)
  4. Factor XII deficiency
  5. Factor XI deficiency
  6. Contact factor deficiency e.g. prekallikrein (not clinically important)
  7. Artefact (incorrect amount of blood in the tube)

Normal Level:  12-16 sec

cause of increase PT:

  • Deficiencies of factor 2,5,6 or 10
  • Severe fibrinogen deficiency

Normal Level : 

1.5-4 g/L


cause of decrease Fibrinogen:

  • Liver failure 
  • DIC

Bleeding time normal: 2 to 7 minute

BT Increase: > 9 min

  1. Blood vessel defect.
  2. Platelet count may be decreased, or there is a defect in their function.
  3. Thrombocytopenia.
  4. Disseminated intravascular coagulation (D I C) where the platelets are consumed.
  5. Acute Leukemia.
  6. Coagulation factor deficiencies like Factor I, II, V, VIII,  IX, and XI may show some increase.
  7. Hodgkin’s disease.
  8. Severe hepatic disease.
  9. Hemolytic disease of the newborn.
  10. Patients with uremia where there are a decrease and dysfunction of platelets.
  11. Patients with anti-inflammatory drugs like aspirin and indomethacin.
  12. In Von Willebrand disease.


Normal Clotting Time (CT)

  1. The expected range is 4 to 10 minutes.
  2. The glass tube method clotting time is 5 to 15 minutes.
  3. Siliconized tube’s clotting time is 19 to 60 minutes 

Causes Of Prolonged Clotting Time:

  1. Coagulation factors deficiencies may be:
    1. Congenital.
    2. Acquired.
    3. Severe deficiency of any known plasma clotting factors except XIII (fibrin-stabilizing factor) and VII.
  2. Drugs like heparin and thrombin inhibitors.
    1. Marked hyperheparinemia.
  3. Afibrinogenemia.