Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 14-09: Acquired Disorders of Coagulation + Key Features Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ Concomitant low factor V activity level not indicative of isolated vitamin K deficiency but may indicate an underlying defect in liver synthetic function + Treatment Download Section PDF Listen +++ ++ 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