Met 2: Fat Soluble Vitamins Flashcards
Can we synthesize vitamins?
No, vitamins are by definition essential
(we can’t synthesize enough)
Which water soluble vitamin is stored?
B12
All other water soluble vitamins do NOT have stores
Water soluble vitamins are
- ______ absorbed from diet
- excreted in _______
- have _____ toxicity potential
Water soluble vitamins are
- easily absorbed from diet
- excreted in urine
- have low toxicity potential
Which has greater potential for toxicity: water or fat soluble vitamins? Why?
Fat soluble vitamins have greater risk of toxicity
B/c they can build up in stores
Malabsorption syndrome pts will have decreased absorption of which type of vitamins?
Fat-soluble, b/c those require with fat absorption
(eg Celiac disease, CF)
Vitamin A (aka retinol) Functions (3)
- Retinol is the chemical that changes shape in respond to light and starts photoreception (esp impt in rods)
- Maintains epithelial surfaces
- Immune function
What are the two forms of dietary Vitamin A?
Where is each found?
- Pre-formed retinyl palmitate
- oily animal products (eg. liver, dairy)
- Precursor beta carotene
- Deep yellow and green veggies
Which form of Vitamin A intake is non-toxic?
Beta-carotene (found in deep yellow/green veggies) is non-toxic b/c body won’t convert more than it needs
What are signs/symptoms of Vitamin A deficiency? (3)
- EYE: Xerophthalmia (cornea dryness) -> corneal opacification
- Night blindness and blindness
- EPITH: epithelium becomes dry and keratinized
- IMMUNE: increased infections, measles complications
What is the name of the early spots on sclera due to Vitamin A deficiency?
Bitot’s spots
Symptoms of Vitamin A Toxicity (4)
Does this occur with all forms of Vitamin A?
- Increased ICP -> nausea, headache
- Bone pain
- Liver damage
- Teratogenic
This does not occur with beta carotene
How does serum vitamin A relate to stores of Vitamin A?
Serum retinol will not decrease until liver stores are totally empty. So a normal serum retinol could mask Vitamin A depletion.
Vitamin D function (4)
- Bone health
- Body will degrade bones if insufficient serum Ca
- Immune Function
- Regulates cell growth and differentiation
- Hormones, membrane receptors
Name the 3 steps of Vitamin D metabolism
- Precursor in skin gets converted to cholecalciferol (D3) by sunlight
- Liver hydroxylates Vitamin D to make calcidiol
- Kidney hydroxylates Calcidiol to make calcitriol
Which form of Vitamin D do we measure?
Calcidiol (after liver hydroxylation)
Milk, orange juice, fish, egg yolks are good sources of….
Vitamin D
What value indicates Vitamin D deficiency?
Vitamin D less than 20
What is the classical syndrome of Vitamin D deficiency?
What are the 3 lab findings?
Rickets: a failure of bone calcification
Labs
- Reduced calcium
- Reduced phosphate
- Elevated alk phosphate
Bowed legs, wide wrists, fractures, and bone pain would indicate…
Rickets
Disease in which two organs can cause Vitamin D deficiency?
What demographic is most at risk of Vitamin D deficiency?
Liver and kidney (b/c hydroxylation occurs here)
Darkly pigmented people at high risk
A pt has vomiting and seizures. Ultrasound/PE shows nephrocalcinosis and soft tissue calcinosis. Which Vitamin is present in insuff/toxic quantities?
This is a Vitamin D overdose. The main finding is symptoms related to hypercalcemia
Function of Vitamin E (1)
Antioxidant
Sunflower oil, corn oil, and other polyunsaturated fats are a good source of….
Vitamin E
Symptoms of Vitamin E deficiency (2)
- Neurologic Degeneration (may be irreversible)
- Loss of reflexes
- Ataxia
- Hemolytic anemia
Vitamin K Function (1)
Sources (2)
Production of clotting factors
Found in green leafy vegetables and produced by gut bacteria
A newborn has purpura and GI bleeding. What Vitamin are they lacking?
What is the potential scary complication?
Lacking Vitamin K
Can get cerebral hemorrhage
Why are newborns at such risk of Vitamin K deficiency hemorrhage? (2)
Because breast milk does not contain Vitamin K and they don’t yet have the gut bacteria to synthesize Vitamin K
How is Vitamin K involved in clotting factor synthesis?
What clotting factors require Vitamin K?
Vitamin K needed for gamma-carboxylation of glutamate
Clotting factors 2, 7, 9, 10, Protein C/S
Vitamin K deficient newborns will have
_____ PT
______ aPTT
_______ bleeding time
Vitamin K deficient newborns will have
elevated PT
elevated aPTT
normal bleeding time (platelets unaffected)
