Met 2: Fat Soluble Vitamins

Question 1

Can we synthesize vitamins?

Answer 1

No, vitamins are by definition essential

(we can’t synthesize enough)

Question 2

Which water soluble vitamin is stored?

Answer 2

B12

All other water soluble vitamins do NOT have stores

Question 3

Water soluble vitamins are

• ______ absorbed from diet
• excreted in _______
• have _____ toxicity potential

Answer 3

Water soluble vitamins are

• easily absorbed from diet
• excreted in urine
• have low toxicity potential

Question 4

Which has greater potential for toxicity: water or fat soluble vitamins? Why?

Answer 4

Fat soluble vitamins have greater risk of toxicity

B/c they can build up in stores

Question 5

Malabsorption syndrome pts will have decreased absorption of which type of vitamins?

Answer 5

Fat-soluble, b/c those require with fat absorption

(eg Celiac disease, CF)

Question 6

Vitamin A (aka retinol) Functions (3)

Answer 6

• Retinol is the chemical that changes shape in respond to light and starts photoreception (esp impt in rods)
• Maintains epithelial surfaces
• Immune function

Question 7

What are the two forms of dietary Vitamin A?
Where is each found?

Answer 7

• Pre-formed retinyl palmitate
  
  • oily animal products (eg. liver, dairy)
• Precursor beta carotene
  
  • Deep yellow and green veggies

Question 8

Which form of Vitamin A intake is non-toxic?

Answer 8

Beta-carotene (found in deep yellow/green veggies) is non-toxic b/c body won’t convert more than it needs

Question 9

What are signs/symptoms of Vitamin A deficiency? (3)

Answer 9

• EYE: Xerophthalmia (cornea dryness) -> corneal opacification
  
  • Night blindness and blindness
• EPITH: epithelium becomes dry and keratinized
• IMMUNE: increased infections, measles complications

Question 10

What is the name of the early spots on sclera due to Vitamin A deficiency?

Answer 10

Bitot’s spots

Question 11

Symptoms of Vitamin A Toxicity (4)

Does this occur with all forms of Vitamin A?

Answer 11

• Increased ICP -> nausea, headache
• Bone pain
• Liver damage
• Teratogenic

This does not occur with beta carotene

Question 12

How does serum vitamin A relate to stores of Vitamin A?

Answer 12

Serum retinol will not decrease until liver stores are totally empty. So a normal serum retinol could mask Vitamin A depletion.

Question 13

Vitamin D function (4)

Answer 13

• Bone health
  
  • Body will degrade bones if insufficient serum Ca
• Immune Function
• Regulates cell growth and differentiation
• Hormones, membrane receptors

Question 14

Name the 3 steps of Vitamin D metabolism

Answer 14

1. Precursor in skin gets converted to cholecalciferol (D3) by sunlight
2. Liver hydroxylates Vitamin D to make calcidiol
3. Kidney hydroxylates Calcidiol to make calcitriol

Question 15

Which form of Vitamin D do we measure?

Answer 15

Calcidiol (after liver hydroxylation)

Question 16

Milk, orange juice, fish, egg yolks are good sources of….

Answer 16

Vitamin D

Question 17

What value indicates Vitamin D deficiency?

Answer 17

Vitamin D less than 20

Question 18

What is the classical syndrome of Vitamin D deficiency?

What are the 3 lab findings?

Answer 18

Rickets: a failure of bone calcification

Labs

• Reduced calcium
• Reduced phosphate
• Elevated alk phosphate

Question 19

Bowed legs, wide wrists, fractures, and bone pain would indicate…

Answer 19

Rickets

Question 20

Disease in which two organs can cause Vitamin D deficiency?

What demographic is most at risk of Vitamin D deficiency?

Answer 20

Liver and kidney (b/c hydroxylation occurs here)

Darkly pigmented people at high risk

Question 21

A pt has vomiting and seizures. Ultrasound/PE shows nephrocalcinosis and soft tissue calcinosis. Which Vitamin is present in insuff/toxic quantities?

Answer 21

This is a Vitamin D overdose. The main finding is symptoms related to hypercalcemia

Question 22

Function of Vitamin E (1)

Answer 22

Antioxidant

Question 23

Sunflower oil, corn oil, and other polyunsaturated fats are a good source of….

Answer 23

Vitamin E

Question 24

Symptoms of Vitamin E deficiency (2)

Answer 24

• Neurologic Degeneration (may be irreversible)
  
  • Loss of reflexes
  • Ataxia
• Hemolytic anemia

Question 25

Vitamin K Function (1)

Sources (2)

Answer 25

Production of clotting factors

Found in green leafy vegetables and produced by gut bacteria

Question 26

A newborn has purpura and GI bleeding. What Vitamin are they lacking?

What is the potential scary complication?

Answer 26

Lacking Vitamin K

Can get cerebral hemorrhage

Question 27

Why are newborns at such risk of Vitamin K deficiency hemorrhage? (2)

Answer 27

Because breast milk does not contain Vitamin K and they don’t yet have the gut bacteria to synthesize Vitamin K

Question 28

How is Vitamin K involved in clotting factor synthesis?

What clotting factors require Vitamin K?

Answer 28

Vitamin K needed for gamma-carboxylation of glutamate

Clotting factors 2, 7, 9, 10, Protein C/S

Question 29

Vitamin K deficient newborns will have

_____ PT

______ aPTT

_______ bleeding time

Answer 29

Vitamin K deficient newborns will have

elevated PT

elevated aPTT

normal bleeding time (platelets unaffected)