Vit K

Question 1

2 different types of Vit K and source

Answer 1

Phylloquinone - natural form found in food (K1) 10% of total liver stores
Menaquinone - made by intestinal bacteria (Ks Mk-4) 90% of total liver stores

Question 2

Major storage for Vit K

Answer 2

Liver (most proteins that need it are here)

Question 3

What is the function of Vit K

Answer 3

Blood Clotting and bone formation:
Post translation Modification of glutamic acid of calcium binding proteins to add a neg change (COO-) which allows calcium to bind

Question 4

Vit K cycle

Answer 4

1. Vit K uses NADPH to reduce quinone to hydroquinone (active)
2. Vit-K carboxylase adds COO to Protein group (ex. Osteocalcin, prothrombin)
3. Vit-K is now a Epoxide which uses Epoxide reductase to reduce back to Vit K

Question 5

All factors are proteins made in the liver that need for K for?

Answer 5

modification, add 1-2 negatives which allow them to take on calcium

Question 6

When will a protein become active that needs Vit K?

Answer 6

After addition of calcium

Question 7

Osteocalcin

Answer 7

Glutamic acid rq vit K
Made from osteoblast - (vit D)
Found in kidney, lung, spleen
Bind to hydroxyapatite (mineralizes bone)

Question 8

Matrix Gla Protein (MGP)

Answer 8

Rq. Vit-K, expressed in developing bone for bone organization
inhibits inappropriate calcification of epiphyseal growth plate

Question 9

Protein S

Answer 9

Modulates cell proliferation

Question 10

Gas6 Protein

Answer 10

Needed for neuronal development

Question 11

Absorption of Vit K depends on

Answer 11

Bile salts and lipids in the jejunum

Question 12

Is Vit K excreted in the urine?

Answer 12

No, in the feces in large quantities (from bacteria sources)
60-70% of phylloquinone absorbed will be excreted

Question 13

Sources of Vit K

Answer 13

Intestinal bacterial synthesis (enough to meet the body needs)
Green leafy vegetables
Soybeans, beef, liver - low in poly high in mena
Olive, canola, soybean oil

Question 14

Who is at risk for a Vit K deficiencies

Answer 14

Newborns: Hemorrhagic disease, VKDB (have no microbiome)
Adults: Antibiotic or anticoagulants/ malabsorption / biliary obstruction

Question 15

Explain why infants are at risk for VKDB (Vit K deficiency bleeding)

Answer 15

Low at birth, and low precursors
limited placental transfer
several weeks to develop liver stores based on mothers milk

Question 16

DRI for Vit K

Answer 16

AI = 90(F) - 120(M) ug/d

Question 17

Ways to assess Vit K status

Answer 17

Prothrombin status: How long it takes to clot. #1 used

Serum levels of phylloquinone: 8hr 1/2 life, not a good marker of body status (diet)

Undercarboxylated protein (PIVKA II): increase would indicate deficiency >3ng/ml, influenced by liver dysfunction - no clinically used

Question 18

Symptoms of deficiency

Answer 18

Adults: hemorrhage, increased bruising,
– Abnormal coagulation is a result of malabsorption or binary obstruction

Question 19

Warfin

Answer 19

Anticoagulant - used at the start of the cycle (quinone reductase) or end of the cycle (epoxide reductase) to inhibit vit K