Fat Soluble Vitamins

Question 1

situations that put a patient at risk for micronutrient deficiency

Answer 1

inadequate intake
increased requirements unmet by food selections
increased metabolic demands
maldigestion and malabsorption
Drug-nutrient or medical treatment-nutrient interactions
“Requirements” for pharmacologic doses

Question 2

Function of Vitamin A (retinol/retinal)

Answer 2

essential in photochemical basis of vision (signals in retina –> brain visual cortex)
maintenance of conjunctival membranes and cornea
critical for epithelial cell differentiation and proliferation

Question 3

Food sources of vitamin A (retinol/retinal)

Answer 3

preformed: liver, dairy, egg yolks, fish oil

Precorsor (beta carotene): deep yellow/orange and green vegetables

Question 4

Consequences of vitamin A deficiency

Answer 4

night bindness and xerophthalmia (extreme dryness of cornea)
Immune deficiency
Abnormal epithelial morphology

Question 5

Symptoms of vitamin A toxicity

Answer 5

Only with preformed vitamin A

vomiting, ICP, headache, bone pain (periosteal proliferation), bone mineral loss, liver damage, death

Question 6

Lab evaluation of vitamin A

Answer 6

serum retinol (normal unless liver stores exhausted; low in presence of acute phase reactants)

Question 7

Function of Vitamin D

Answer 7

hormone
maintains Ca in physiologic range
stimulates intestinal and renal absorption of Ca and P, and mobilization of Ca and P from bone

Question 8

Sources of Vitamin D

Answer 8

precursor (dehydrocholesterol) in skin –> cholecalciferol (D3) by UV light
Diet: fish oils, fatty fish, egg yolks, milk and formulas

Question 9

Absorption of Vitamin D

Answer 9

via chylomicrons

Question 10

metabolism of vitamin D

Answer 10

D2 or D3 hydroxylated in liver –> 25-hydroxycholecalciferol –> 1,25-dihydroxy-cholecalciferol (calcitrol) in kidney

Question 11

Vitamin D levels indicating deficiency

Answer 11

less than 20 ng/ml

Question 12

Consequences of vitamin D deficiency

Answer 12

Rickets = failure of maturation of cartilage and calcification; rachitic rosary on ribs, bowed legs, widened metaphyses, painful bones, fractures

Question 13

labs indicating Vitamin D deficiency

Answer 13

low 25(OH) vit D, high PTH
late findings: classic triad of low Ca and P, high alk phos

Question 14

Levels at vitamin D toxicity

Answer 14

> 10,000 IU/d for weeks

Question 15

Consequences of vitamin D toxicity

Answer 15

hypercalcemia, vomiting, seizures; nephrocalcinosis and soft tissue calcification

Question 16

Function of vitamin E

Answer 16

antioxidant, free radical scavenger, cell membrane stabilizer

Question 17

Sources of vitamin E

Answer 17

polyunsaturated vegetable oils, wheat germ

Question 18

Consequences of vitamin E deficiency

Answer 18

neurodegeneration and hemolytic anemia

Question 19

Consequences of vitamin E toxicity

Answer 19

low risk. coagulopathy at very high doses (inhibit vitamin K-dependent factors)

Question 20

Function of vitamin K

Answer 20

essential for carboxylation of coagulation proteins II (prothrombin), VII, IX, X

Question 21

Sources of vitamin K

Answer 21

leady vegetables, fruits, seeds

synthesized by intestinal bacteria

Question 22

Consequences of vitamin K deficiency

Answer 22

prolonged coagulation times

hemorrhagic disease of newborn