Vitamin K

Question 1

Vitamin K is known as what

Answer 1

The blood clotting vitamin

Question 2

Vitamin K - Structures

Answer 2

Differ only on side chain…

•   Phylloquinone - plants (Vitamin K1)
•   Menaquinone (K2) - Bacterial sources within the gut of animals and people (n = 5)
•   Menadione (K3) - synthetic source

Question 3

Vitamin K - Function

Answer 3

1.   Serves as a co-factor in carboxylation reactions of proteins that are necessary for blood coagulation.
2.   Promotes bone health via carboxylation of osteocalcin, a protein involved in bone mineralization;

Question 4

Vitamin K Metabolism

Answer 4

•   Vitamin Ks are absorbed readily with fat in GI tract;

-   Liver converts all forms to K2

Question 5

Vitamin K - Requirement

Answer 5

Menadione = 0.5 mg/kg diet

Question 6

Vitamin K toxicity

Answer 6

None

Question 7

Vitamin K - Deficiency

Answer 7

Deficiency:
-  Prolonged clotting time;
-  Hemorrhaging;
-  Gut microbes synthesis vit. K, thus deficiency is rare, except…
-  Treatment w/ some antibiotics & antimicrobials
(Chicks fed sulfaquinoxaline to control coccidiosis develop vit. K def.)
-  Moldy sweet clover which contains dicumerol; (A concern with grazing animals)
-  Warfarin (rat poison)
-  Both dicumerol & warfarin are competitive inhibitors (anti-vitamins) of vitamin K
(Most frequently a problem for cats, dogs, and children)