3.1 Vitamin K deficiency

• What can excessive bleeding result from?

  Deficiency of blood-clotting factors
• What are the three types of bleeding tendencies discussed?

  1. Vitamin K deficiency
  2. Hemophilia
  3. Thrombocytopenia (platelet deficiency)
• How does vitamin K deficiency affect blood clotting?

  It decreases prothrombin and clotting factors
• Where are most blood-clotting factors formed?

  Liver
• What diseases can depress the clotting system?

  Hepatitis, cirrhosis, acute yellow atrophy
• What role does vitamin K play in clotting factor formation?

  It adds a carboxyl group to clotting factors
• What happens to vitamin K after it adds a carboxyl group?

  It becomes oxidized and inactive
• What enzyme reduces vitamin K back to its active form?

  Vitamin K epoxide reductase complex 1 (VKOR c1)
• What can result from insufficient coagulation factors in the blood?

  Serious bleeding tendencies
• How is vitamin K synthesized in healthy individuals?

  By bacteria in the intestinal tract
• Why is vitamin K deficiency rare in healthy persons?

  Due to synthesis by intestinal bacteria
• In which group is vitamin K deficiency more likely to occur?

  Persons with gastrointestinal disease
• Why does vitamin K deficiency often occur in gastrointestinal disease?

  Poor absorption of fats affects vitamin K
• What is a prevalent cause of vitamin K deficiency?

  Failure of the liver to secrete bile
• How does lack of bile affect vitamin K absorption?

  It prevents adequate fat digestion and absorption
• What happens to prothrombin production in liver disease?

  It decreases due to poor vitamin K absorption
• When is vitamin K injected into surgical patients?

  Before surgery in liver disease cases
• How long before surgery should vitamin K be given?

  4 to 8 hours before the operation
• What is required for sufficient clotting factors to be produced?

  Liver cells must be at least half normal
• How does liver disease affect both vitamin K absorption and clotting factor production?

  It decreases absorption and production of factors