Disorders of hemostasis

• Haemostasis – stoppage of bleeding, takes place at three levels:
  • primary hemostasis – vessel vasoconstriction, platelet aggregation and platelet degranulation,
  • secondary hemostasis – hemocoagulation,
  • fibrinolysis – dissolution of the thrombus.
• Disorders of hemostasis are the result of an imbalance between pro- and anti-coagulation factors , they can be twofold:
  • hemorrhagic diatheses - bleeding,
  • thromboembolic disease – thrombophilic conditions (Thrombosis and Embolism).

Hemorrhagic diatheses

• Disorders of primary hemostasis ,
  • Vasculopathy (vasculitis, congenital connective tissue disorders, vitamin C deficiency)
  • Thrombocytopenia (autoimmune – ITP, TTP, with hypersplenism)
  • Thrombocytopathy.
• Disorders of secondary hemostasis
  • congenital (lack of one factor) – hemofilie A (VIII), hemofilie B (IX),
    • afibrinogenemia,
    • acquired (mostly several coagulation factors are missing) – Vitamin K, Liver insufficiency.

 For more information see Bleeding conditions (pediatrics).

Thrombophilic conditions

• Congenital – defective hemocoagulation or fibrinolytic factors
  • Leiden Mutation (factor V mutation),
  • factor II mutation,
  • deficiency of antithrombin III, proteins C and S, Hyperhomocysteinemia.
• Acquired – ( Virchow's trias ), these are actually risk factors for phlebothrombosis:
  • stasis (postoperative period, postpartum period, pregnancy),vascular wall damage (injuries, burns, varicosities, Sepsis, post-thrombotic syndromes),
  • blood abnormalities (pregnancy, oral contraceptives, malignancies,Nephrotic syndrome,trauma, burns, infections),
  • the main risk factors are age (over 40) and gender (women – estrogens, contraceptives), as well as smoking and Obesity.

Hemocoagulation examination

• INR (formerly Quick, PT) - external system , to control warfarinization, norm 0.8-1.2.
• APTT – internal system , for checking heparinization, standard 30–45 s.
• TT thrombin time) – the last phase of coagulation (thrombin catalyzing the conversion of fibrinogen to fibrin), the norm is 10–20 s.
• Euglobulin fibrinolysis – dissolution of fibrin clot in euglobulin plasma, standard 120–240 min.
• FDP, D-dimers .
• Fibrinogen – norm 2–4 g/l.

Overview of antithrombotic treatment

• Anticoagulants – act against the formation of a thrombus,
  • direct (they inactivate the coagulation factors present) heparin (UFH), LMWH
  • indirect (acts against the synthesis of coagulation factors)- warfarin, ethyl biscum acetate (Pelentan),
• Fibrinolytics – they dissolve an already formed thrombus - both venous and arterial
  • streptokinase, urokinase,
  • rt-PA (alteplase)... "Actilyse"
• Antiaggregant - acts against the aggregation of platelets (prevention of the formation of a platelet thrombus - mainly as a prevention of arterial thrombosis, not as a prevention of deep vein thrombosis)
  • ASA, dipyridamole, ticlopidine, clopidogrel, abciximab, pentoxifylline.

Antidote

• Protamine - the antidote of heparin.
• Vitamin K –antidote to coumarin derivatives (warfarin).
• Aprotinin, aminocaproic acid – an antidote to fibrinolytics.

Links

related articles

• Bleeding conditions (pediatrics) • Hemorrhagic diatheses (pathology) • Hereditary coagulopathy • Acquired coagulopathy • Thrombocytopathy
• Hemostasis • Hemocoagulation • Examination of blood coagulation • Examination of bleeding

Source

• BENEŠ, Jiří. Studijní materiály [online]. [cit. 29.6.2010]. <http://jirben.wz.cz>.