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For further information, see CMDT Part 14-09: Acquired Disorders of Coagulation

Key Features

  • May occur as a result of

    • Deficient dietary intake (eg, green leafy vegetables and soybeans)

    • Malabsorption

    • Decreased production by intestinal bacteria (due to treatment with chemotherapy or antibiotics)

  • Vitamin K is required for normal function of vitamin K epoxide reductase that assists in posttranslational gamma-carboxylation of the coagulation factors II, VII, IX, and X, which is necessary for their activity

  • Risk of developing vitamin K deficiency is high in hospitalized patients taking broad-spectrum antibiotics who have poor or no oral intake

Clinical Findings

  • Mild to moderate deficiency typically features a prolonged prothrombin time (PT)

  • Severe deficiency: prolonged activated partial thromboplastin time (aPTT) Low levels of individual clotting factors II, VII, IX, and X

Diagnosis

  • Concomitant low factor V activity level not indicative of isolated vitamin K deficiency but may indicate an underlying defect in liver synthetic function

Treatment

  • Vitamin K1 (phytonadione) may be administered via intravenous or oral routes

  • Intravenous administration (1 mg/day) results in faster normalization of a prolonged PT than oral administration (5–10 mg/day)

  • Parenteral doses should be given at lower doses and slowly (eg, over 30 minutes) with concomitant monitoring to avoid possible anaphylaxis

  • Oral absorption is typically excellent; partial improvement in PT should be seen within 18–24 hours

  • Subcutaneous route not recommended due to erratic absorption

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