Vitamin K deficiency - Clotting disorders

Vitamin K deficiency

Definition

Deficiency of vitamin K, a fat-soluble vitamin, leads to a bleeding tendency.

Aetiology

Insufficient vitamin K intake or absorption. Sources of dietary vitamin K include vegetables, peas, beans and liver. Deficiency occurs in obstructive jaundice and certain malabsorption syndromes. Warfarin prevents the reduction of vitamin K to its active form leading to functional vitamin K deficiency.

Pathophysiology

Vitamin K is a co factor in the synthesis of clotting factors II (prothrombin), VII, IX and X. In its absence the factors do not have an active binding site and are there-fore functionally deficient. Vitamin K is also involved in producing proteins required for bone calcification.

Clinical features

Patients present with bruising, mucosal bleeding and haematuria.

Investigations

The prothrombin time and the partial thromboplastin time are prolonged.

Management

Vitamin K (phytomenadione) can be given as iv. or im injections. If given orally in malabsorption syndromes it must be in a water-soluble form.