Vitamin K and Blood Clotting

Question 1

What is the primary role of vitamin K in blood clotting?

Answer 1

Vitamin K is essential for the carboxylation of certain glutamate residues in proteins to form gamma-carboxyglutamate, which is necessary for blood clotting.

Question 2

Which clotting factors require vitamin K for their synthesis?

Answer 2

Factors II (prothrombin), VII, IX, and X.

Question 3

How does vitamin K facilitate the activation of clotting factors?

Answer 3

Vitamin K acts as a cofactor for the enzyme gamma-glutamyl carboxylase, which carboxylates glutamate residues on clotting factors.

Question 4

What is the dietary form of vitamin K called?

Answer 4

Phylloquinone (vitamin K1).

Question 5

Which form of vitamin K is synthesized by gut bacteria?

Answer 5

Menaquinone (vitamin K2).

Question 6

Name the enzyme that vitamin K acts as a cofactor for in the clotting process.

Answer 6

Gamma-glutamyl carboxylase.

Question 7

What is the function of gamma-carboxyglutamate residues in clotting factors?

Answer 7

Gamma-carboxyglutamate residues allow clotting factors to bind calcium, which is essential for their activation.

Question 8

How does warfarin interfere with vitamin K activity?

Answer 8

Warfarin inhibits vitamin K epoxide reductase, preventing the recycling of vitamin K.

Question 9

What is the consequence of vitamin K deficiency on clotting?

Answer 9

Increased bleeding and bruising due to impaired clotting factor synthesis.

Question 10

Which population groups are at higher risk of vitamin K deficiency?

Answer 10

Newborns, people with malabsorption disorders, and those on long-term antibiotics.

Question 11

Name a common test used to assess vitamin K status.

Answer 11

Prothrombin time (PT) test.

Question 12

How is vitamin K absorbed in the body?

Answer 12

Vitamin K is absorbed in the small intestine along with dietary fats.

Question 13

Which organ is primarily responsible for storing vitamin K?

Answer 13

The liver.

Question 14

What role does vitamin K play in the activation of protein C and protein S?

Answer 14

Vitamin K is required for the gamma-carboxylation and activation of protein C and protein S, which are anticoagulants.

Question 15

How does chronic antibiotic use affect vitamin K levels?

Answer 15

It can reduce gut bacteria that synthesize vitamin K2, leading to lower levels.

Question 16

What is the relationship between vitamin K and osteocalcin?

Answer 16

Vitamin K is necessary for the carboxylation of osteocalcin, a protein involved in bone metabolism.

Question 17

Which fat-soluble vitamin works closely with vitamin K in bone metabolism?

Answer 17

Vitamin D.

Question 18

What are the two main forms of vitamin K found in supplements?

Answer 18

Phylloquinone (K1) and menaquinone (K2).

Question 19

Name a medical condition that might require vitamin K supplementation.

Answer 19

Hemorrhagic disease of the newborn.

Question 20

How does liver disease affect vitamin K metabolism?

Answer 20

Liver disease can impair the storage and metabolism of vitamin K, leading to deficiency.

Question 21

What is the role of vitamin K in the synthesis of prothrombin?

Answer 21

Vitamin K is required for the carboxylation of prothrombin, converting it into its active form.

Question 22

Which type of diet might lead to reduced vitamin K intake?

Answer 22

Diets low in leafy green vegetables.

Question 23

What is the recommended daily allowance (RDA) of vitamin K for adults?

Answer 23

90-120 micrograms per day for adults.

Question 24

How does vitamin K contribute to the regulation of calcium in the body?

Answer 24

Vitamin K-dependent proteins help regulate calcium deposition in bones and prevent arterial calcification.

Question 25

What are the symptoms of vitamin K toxicity?

Answer 25

Toxicity is rare but can cause jaundice and hemolytic anemia.

Question 26

Which blood thinner requires monitoring of vitamin K intake?

Answer 26

Warfarin.

Question 27

How does newborn vitamin K prophylaxis prevent bleeding disorders?

Answer 27

It prevents vitamin K deficiency bleeding (VKDB) in newborns.

Question 28

Name a leafy green vegetable high in vitamin K.

Answer 28

Spinach.

Question 29

What is the effect of bile acid sequestrants on vitamin K absorption?

Answer 29

Bile acid sequestrants can reduce the absorption of fat-soluble vitamins, including vitamin K.

Question 30

How does vitamin K recycling occur in the body?

Answer 30

Vitamin K recycling occurs via the vitamin K epoxide reductase complex, which regenerates active vitamin K from its epoxide form.