AFIBRINOGENEMIA

• Biochemical aspects:
  • Fibrinogen is a symmetrical dimer that contains three pairs of different polypeptide chains (alpha, beta, and gamma) linked by disulfide bonds. The molecular weight of fibrinogen is about 340,000.
  • The conversion of fibrinogen to fibrin results from the thrombin-mediated cleavage of arginine-glycine bonds.
  • Plasmin progressively digests fibrinogen ultimately yielding the plamin-resistant fragments D and E.
• Pathological Basis:
  • Mode of inheritance: autosomal recessive. Consequently, the absence of a family history of afibrinogenemia is typical.
  • Patients with this disorder may have a clinical picture consistent with abnormalities of both primary and secondary hemostasis.
  • Adequate hemostasis is achieved with a fibrinogen level of 50 -100 mg/dl.
• Treatment:
  • Cryoprecipitate.
  • Avoidance of aspirin-containing compounds.
  • Dosage: the amount of fibrinogen (in mg) required can be calculated from:
    • 40*BW*(desired fibrinogen level-actual fibrinogen level)/100
    • where BW is body weight in kg