Vitamins B&B Flashcards
vitamin A, aka ______, is important for… (2)
vitamin A = retinol
- vision (esp. rods - night vision)
- cell differentiation (recall high doses of vitamin A can treat AML, among other cancers)
the major source of vitamin A (retinol) is…
beta carotene (pro-vitamin A) - has antioxidant properties
can get from liver, dark green or yellow vegetables
vitamin A is sometimes used as therapy for what type of cancer?
AML (acute promyelocytic leukemia) - classic finding is Auer rod
Vitamin A given as all-trans-retinoic acid —> induces malignant cells to complete differentiation
vitamin C, aka _____, is important for… (4)
vitamin C = ascorbic acid, water soluble, required for:
- iron absorption (non-heme - requires reduction)
- collagen hydroxylation in ER
- dopamine conversion to NE
- antioxidant
what are 2 major concerns of vitamin C excess?
- iron overload (in predisposed patients) - Vitamin C enhances iron absorption
- calcium oxalate kidney stones - Vitamin C metabolized into oxalate
from where are the 2 forms of vitamin D found?
Vitamin D2 (ergocalciferol) - found in plants
Vitamin D3 (cholecalciferol) - found in fortified milk or synthesis induced via sunlight
what must happen to Vitamin D for it to be activated?
must be hydroxylated, first in liver (step 1), then in kidney (step 2 - regulated by PTH)
recall active form is 1,25-OH Vitamin D (calcitriol)
sarcoidosis can lead to rogue activation of which vitamin?
macrophages in sarcoidosis induce activation of vitamin D to 1,25-OH Vit. D (hydroxylated)
[recall normally this occurs in proximal tubule of kidney]
describe the effects of vitamin D on the GI and bones
major mechanism is increased Ca2+ and PO4 absorption in GI
at abnormally high levels, paradoxical effect can occur in bones which causes Ca2+/PO4 resorption
how does vitamin D deficiency present?
poor GI absorption of Ca2+/PO4 —> tetany and seizures due to hypocalcemia
also poor bone mineralization —> osteomalacia (adults), rickets (children)
[note that vitamin D deficiency is really just the same as having calcium deficiency]
vitamin E, aka _____, has a key role in…
vitamin E = tocopherol
antioxidant, key role in protecting RBC from oxidative damage (scavenges free radicals)
how would a vitamin E deficiency present?
vitamin E = tocopherol, antioxidant
deficiency (v rare) —> hemolytic anemia, muscle weakness, ataxia, loss of proprioception
what are the vitamin K dependent clotting factors?
factors II (2), VII (7), IX (9), X (10), C, and S
require post-translational modification by vitamin K (deficiency —> bleeding)
where does vitamin K come from?
green, leafy vegetables (K1 form - phylloquinone)
synthesized by GI bacteria (K2 form - menaquinone)
what enzyme does warfarin inhibit to cause vitamin K antagonism?
warfarin blocks epoxide reductase, which reduces vitamin K
vitamin K in its reduced form is required because it is oxidized in the process of activating clotting factors (therefore, warfarin blocks the renewal of this resource!)
