Hypoprothrombinemia is a blood disorder in which a deficiency of prothrombin (Factor II of the coagulation cascade) results in impaired blood clotting, leading to an increased physiological risk for bleeding, especially in the gastrointestinal system, cranial vault, and superficial integumentary system.
- Bleeding problems
- Easy bruising
- Reduced blood prothrombin level
- Poor blood clotting
Acquired hypoprothrombinemia is autoimmune and associated with the lupus anticoagulant. A common form of acquired hypoprothrombinemia is vitamin K deficiency. Levels of other vitamin K–dependent procoagulant factors (factors VII, IX, and X) and anticoagulant factors (protein C and protein S) are also decreased in vitamin K deficiency.
Inherited prothrombin deficiency is rare and they have two phenotypes, which are hypoprothrombinemia (type I deficiency) and dysprothrombinemia (type II deficiency). In type I deficiency, prothrombin levels and prothrombin activity are reduced. In type II deficiency, prothrombin activity is reduced, but prothrombin levels are in the reference range. Both disorders are autosomal recessive.
The prognosis for patients with inherited prothrombin deficiency varies. The degree of deficiency does not always predict the clinical course, as patients with severe deficiency with only mild bleeding tendencies have been reported.
The treatment of hypoprothrombinemia depends on the underlying etiology. Plasma-derived products that contain factor II are available. Vitamin K-1 (phytonadione) is used to treat vitamin K deficiency as well as warfarin overdose. In autoimmune disease, treatment is not entirely straightforward, and immunosuppressive therapy is used in severe cases