prothrombin deficiency (hypoprothrombinemia)

Etiology

• acquired:
  • autoimmune, lupus antigoagulant (prothrombin inhibitor)
  • vitamin K deficiency
    • anticoagulants (warfarin)
    • antibiotics inhibit vitamin K synthesis by gut bacteria
• inherited

Epidemiology

• inherited prothrombin deficiency is rare
• autoimmune forms may occur at any age, otherwise a disease of infants

Genetics

• associated with defects in prothrombin (coagulation factor II)

Clinical manifestations

• easy bruising
• epistaxis
• prolonged bleeding with injury, tooth extraction, or surgery
• oral mucosal bleeding
• melena
• hematochezia
• hematuria
• Intracranial hemorrhage
• hemarthroses
• menorrhagia

Laboratory

• prothrombin time (PT) increase
• aPTT increased
• with vitamin K deficiency, decreased
  • plasma factor VII
  • plasma factor IX
  • plasma factor X
  • plasma protein C
  • plasma protein S

Management

• replenish vitamin
• fresh frozen plasma contains ~ 1 U/mL of prothrombin
• prothrombin concentrate available
• lupus anticoagulant has been treated with
  • glucocorticoids
  • intravenous immunoglobulin
  • fresh-frozen plasma
  • azathioprine
  • epsilon aminocaproic acid (Amicar)
    • minimizes severity of mucosal bleeding
    • enhances hemostasis when fibrinolysis contributes to bleeding
• avoid surgery if possible
  • use of prothrombin concentrate if surgery necessary
  • attempt to decrease inhibitor titer (if present)
• avoid contact sports

More general terms

• coagulation factor deficiency

More specific terms

• antibiotic-induced prothrombin deficiency
• anticoagulant-induced prothrombin deficiency

Database

• OMIM: https://mirror.omim.org/entry/176930