Vitamins Flashcards
B1
thiamine: TPP
B2
riboflavin: FAD, FMN
B3
niacin: NAD+
B5
pantothenic acid: CoA
B6
pyridoxine: PLP
B7
biotin
B9
folate
B12
cobalamin
C
ascorbic acid
fat soluble vitamins
A,D,E,K
vit A (retinol)
- antioxidant
- visual pigments (retinal)
- normal diff of epith cells into specialized tissues
- prevents squamous metaplasia
- tx of measles, AML M3
- in liver (esp polar bears), leafy vegetables, beta-carotene (carrots)
vit A (retinol) deficiency
- night blindness
- dry skin
- bitot spots (dry spots on conjunctiva)
- keratomalacia (wrinkling/clouding of cornea)
- xerophthalmia
- corneal ulcerations
vit A (retinol) excess
- arthralgias, fatigue, HA, sore throat
- alopecia
- skin changes (oranging of skin, dry/pruritic skin)
- teratogenic (cleft palate, cardiac abnorm)
- increased ICP (pseudotumor cerebri)
vit B1
- TPP = active form
- cofactor for enzymes in decarboxylation rxns (pyruvate DH, alpha-ketoglutarate DH, transketolase, branched-chain AA DH)
vit B1 deficiency
- ATP depletion (from impaired glucose breakdown) –> WORSENED w/ glucose infusion
- brain/heart affected first (highly aerobic)
- Wernicke-Korsakoff synd
- Dry beriberi (neuritis, symm muscle wasting)
- Wet beriberi (high-output cardiac failure, dilated cardiomyopathy, edema)
- seen in alcoholics, in malnutrition, and in pts on dialysis
vit B2
- cofactor in oxidation/reduction
- FAD (cofactor for succinate DH + component of ETC complex II)
- FMN (component of ETC complex I)
vit B2 deficiency
- “mouth and eyes”
- cheilosis (inflamm of lips, scaling/fissures @ corners of mouth)
- corneal vascularization
- dermatitis
- stomatitis
- glossitis
vit B3
- NAD+/NADP - used in redox rxns
- derived from tryptophan
- synth req B6 + B2
vit B3 deficiency
- glossitis
- **pellagra: (if severe); aka caused by:
- Hartnup dz - decreased tryptophan absorp
- malig carcinoid synd (increased tryptophan metab)
- INH (decreases B6)
vit B3 excess
facial flushing
vit B5
-component of CoA + fatty acid synthase
vit B5 deficiency
- dermatitis
- enteritis
- alopecia
- adrenal insuff
vit B6
- pyridoxal phosphate = active form
- used in transamination (ALT, AST) and decarboxylation rxns
- cofactor for glycogen phosphorylase
- synth of cystathionine, heme, niacin, histamine, NT (serotonin, epinephrine, NE, GABA)
vit B6 deficiency
- convulsions (bc decreased GABA)
- hyperirritability
- periph neuropathy (deficiency inducible by INH + oral contraceptives)
- sideroblastic anemias (due to impaired Hb synth and Fe excess) - bc lack of ALA-S enzyme
best enzyme to test B1 deficiency?
transketolase
“tea and toast” diet deficiency?
B3 (niacin)
vit B2 impt for what enzymes?
- succinate DH (TCA)
- fatty-acyl CoA DH (beta-oxidation)
- glycerol phosphate shuttle
B7 cofactor for?
carboxylation rxns:
- pyruvate carboxylase (pyruvate (3C) –> OA (4C)) - used in gluconeogenesis
- acetyl-CoA carboxylase (acetyl-CoA (2C) –> malonyl-CoA (3C)) - used in FA synthesis
- propionyl-CoA carboxylase (propionyl-CoA (3C) –> methylmalonyl-CoA (4C)) - used to metabolize odd-chain FA, Val, Met, Ile, Thr (“VOMIT” pathway)
B7 deficiency caused by? causes?
by avidin in egg whites or AB use
causes dermatitis, alopecia, enteritis; also fasting hypoglycemia (loss of pyruvate carboxylase)
deficiency of B9 seen in?
alcoholics and pregnant pts
also w/ several drugs (phenytoin, sulfonamides, MTX, TMP)
B9 function =?
converted to THF = coenzyme for 1C transfer/methylation rxns
impt for synth/repair of DNA and synth of nitrogenous bases in DNA + RNA
B12 function?
cofactor for:
- homocysteine methyltransferase (untraps inactive folate from storage [N5-methyl-THF])
- methylmalonyl-CoA mutase (part of “VOMIT” pathway)
deficiency of vit B12 seen w/?
- malabsorption (enteritis, sprue, Diphyllobothrium latum)
- lack of intrinsic factor
- absence of terminal ileum (Crohn’s disese)
labs show what in B12 def?
increased methylmalonic acid and homocysteine levels
SAM and methionine regen depend on?
vit B12 and folate
4 functions of vit C?
- antioxidant
- facilitate iron absorption by keeping in in reduced (Fe2+) state
- nec for hydroxylation of proline and lysine in collagen synth
- nec for dopamine-beta-hydroxylase (converts dopamine –> NE)
vit D deficiency seen in patients that:
- breast feed
- have dark skin
vit E function?
protect RBCs and membrane lipids from ROS
vit E deficiency?
- hemolytic anemia (bc increased fragility of RBCs)
- (proximal) muscle weakness
- ***posterior column and spinocerebellar tract demyelination (mimics Friedrich’s ataxia; ataxia, dysarthria, loss of proprioception/vibratory sense)
- decrease serum phospholipids and cause infertility
vit E tx for?
abetalipoproteinemia
vit E excess?
hemorrhagic stroke (in adults) necrotizing enterocolitis (in infants)
vit K function
gamma-carboxylation of glutamic acid residues (put another COO- group)
vit K deficiency seen in pts that?
- breast feed
- after prolonged use of broad spectrum AB or phenytoin (wipe out intestinal gut flora)
