vitamins Flashcards
fat-soluble vitamins
ADEK
fat malabsorption diseases = diseases with ADEK deficiency
cystic fibrosis
pancreatic insufficiency
ILEUM pathology (absorption of ADEK)
roles of vitamin D (calcitriol)
intestine: ↑Ca absorption - ↑ expression of Ca binding protein, ↑PO4 + Mg absorption
kidney: ↑ PTH-dependent Ca reabsorption
bone: ↑Ca reabsorption
types of vitamin D deficiency
1) inadequate dietary vitamin D
2) impaired hydroxylation to make 25-OH vitamin D (liver)
3) impaired hydroxylation to make 1,25-(OH)2 vitamin D (kidney)
4) end-organ insensitivity to vitamin D
complications of vitamin D deficiency
demineralization of bone: low vitamin D → no absorption of Ca, PO4 from intestine →↓ serum Ca →↑ PTH → PTH mediated ↑ serum Ca via bone resorption, PTH mediated ↓ PO4 secretion in kidney → no source of Ca or PO4 for strong bones in future
symptoms: bone tenderness, muscle weakness, skeletal deformities - bowing, pathologic fractures, dental problems
children: rickets
adults: osteomalacia
does breast milk have adequate amounts of vit. D
NO. need to supplement
vitamin D toxicity
1) too much vit. D supplementation
2) sarcoidosis: macrophages in granulomas ↑conversion of 25-OH vit. D3 → 1,25-OH2 vit. D3
hypercalcemia: STONES, BONES, GROANS, pyschiatric OVERTONES
role of vitamin K
post-translational modification of various clotting factors (co-factor for gamma-carboxylation of glutamic acid residues in clotting factors)
source of vitamin D
plants (D2)
milk + sunexposed skin (D3)
source of vitamin K
intestinal flora
clotting factors that require vitamin K for activation
CF: 2,7,9,10
protein C + S
prothrombin
CF decreased if take: warfarin (vit. K antagonist)
complications with vitamin D in newborns
newborn has sterile gut - can’t make vitamin K → no clotting factors → hemorrhage
newborns receive single IM dose of vitamin K at birth
vitamin K deficiency
drug-induced: warfarin (coumadin), anticonvulsants (phenytoin), antibiotics (no flora)
types of vitamin A
retinol: eye, immune system, maintenance of epithelial cells + mucous secreting cells
retinal
B-carotene: cleaved in intestine to 2 molecules of retinol
retinoic acid: unusable by body, but can treat some diseases
vitamin A treatment
↓size + secretion of sebaceous glands: mild-mod acne: tretinoin (topical) mild severe acne: isotretinoin (oral) measles AML (M3 type)
vitamin A deficiency
night blindness
xerophthalmia (dry conjunctiva →corneal ulceration)
keratomalacia: wrinkle, clouded cornea
bitot spots: dry silver plaques on bulbar conjunctiva
corneal ulceration
vitamin A deficiency
vitamin A toxicity
headache N/V stupor ↑ ICP: psuedotumor cerebri dry and pruritic hyperlipidemia hepatomegaly +/- cirrhosis bone + joint pain alopecia
contraindication for vitamin A supplementation
pregnancy: teratogen
role of vitamin E (α-tocopherol)
antioxidant: prevent non-enzymatic oxidation of cell components by O2 free radicals (esp RBCs)
vitamin E deficiency
hemolytic anemia: RBC not protected
spinocerebellar degeneration → ataxia
peripheral neuropathy
proximal muscle weakness
antioxidants
vitamin E
vitamin C
water-soluble vitamins
B vitamins
vitamin C
B1 name
thiamine
active form: thiamine pyrophosphate (TPP)
B2 name
riboflavin
active forms:
flavin adenine dinucleotdie: FAD
flavin mononucleotide: FMN
B3 name
niacin
active form:
NAD+
NADP+
B5 name
pantothenic acid
componenent of coenzyme A (coA) which transfers acyl groups
B6 name
pyridoxine
active form:
pyridoxal phosphate: PLP
B7 name
biotin: apoenzymes for carboxylation reactions
“carboxylase” require B7
B9 name
folate/folic acid
synthesis (purine + pyrimidines) + repair of DNA
rapid cell division + growth
biologically active form = tetrahydrofolate (THF): coenzyme for 1 C transfer/methylation
B12 name
cobalamin
co-factor for homocysteine methyltransferase: homocysteine → methionine + THF (active form of folate)
need for DNA synthesis
role of vitamin C (ascorbic acid)
hydroxylation of prolyl + lysyl residues of collagen
dopamine ßhydroxylase needs Ca: dopamine → NE
antioxidant: protect RBCs
facilitates IRON absorption in gut: vitamin C keeps iron in reduced state = easier to absorb (take iron with OJ)
vitamin C deficiency
scurvy: collagen synthesis defect sore, spongy gums loose teeth fragile blood vessels swollen joints hemarthrosis impaired wound healing anemia
role of TPP (thiamine pyrophosphate): active form of B1
1) pyruvate dehydrogenase (TLC for Nobody = cofactors): pyruvate → acetyl CoA (link glycolysis to TCA)
2) α ketoglutarate dehydrogenase: α ketoglutarate → succinyl coA (TCA)
3) transketolase (HMP shunt = pentose phosphate pathway)
thiamine deficiency (B1)
poor nutrition: alcoholism
malabsorption
↑ loss of water-soluble vitamins: dialysis
brain affected first
damage to medial thalamus + mammillary bodies of posterior hypothalamus + general cerebral atrophy
Wernicke-Korsakoff syndrome
Beriberi: dry or wet
role of thiamine
co-factor for oxidative metabolism: need to breakdown glucose → ATP
BRAIN is affected first
Wernicke-Korsakoff syndrome
Wernicke encephalopathy: acute triad: encephalopathy, oculomotor dysfunction, gait ataxia stupor, coma, hypotension, hypothermia Korsakoff syndrome: chronic, consequence of WE memory loss: anterograde + retrograde confabulation: invent memories personality changes apathy
primary food is polished/dehusked rice
beriberi (thiamine deficiency)
dry beriberi
NERVES
peripheral neuropathy with myelin degeneration: toe drop, wrist drop, foot drop
muscle weakness
hyporeflexia or areflexia
wet beriberi
HEART
peripheral vasodilation → high output heart failure
peripheral edema
dilated cardiomyopathy
treatment of thiamine deficiency (B1)
thiamine supplementation (ALWAYS give BEFORE glucose) *giving glucose to thiamine deficient or near-deficient pt → worsen WE
vitamin B2 (riboflavin) deficiency
dermatitis
cheiolosis (scaling and fissures at corners of mouth)
angular stomatitis (mouth)
glossitis
role of FMN/FAD
co-factors for redox reactions
any “dehydrogenase” enzyme requires B2 as cofactor
role of NAD+/NADP+
used in redox reactions
source of B3 (niacin)
tryptophan in diet: NAD+/NADP+
B3 (niacin) deficiency
pellagra: 3 D’s
dermatitis
diarrhea
dementia
causes of B3 (niacin) deficiency
1) Hartnup disease: ↓ tryptophan absorption
2) malignant carcinoid syndrome: ↑ tryptophan metabolism
3) INH (isoniazid): Inhibit B6 + B3
niacin is used for the treatment of
dyslipidemia: ↑ HDL, ↓LDL
SE: flushing reaction: take aspirin 30 min before taking niacin
vitamin B5 deficiency (pantothenate)
dermatitis
enteritis
alopecia
adrenal insufficiency
role of pyridoxal phosphate (PLP)
coenzyme for many enzymes: esp amino acid metabolism (transaminations + deaminations)
conversion of amino acid precursors into: heme, niacin, histamine, GABA, dopa, NE, epi
B6 (pyridoxine) deficiency
similar to riboflavin (B2): angular cheilosis glossitis CONVULSIONS: need B6 to make GABA (main inhibitor NT) PERIPHERAL NEUROPATHY
cause of B6 deficiency
INH for TB inhibits B6 + B3
add B6 to prevent
cause of B7 (biotin) deficiency
avidin (egg whites) prevents absorption of biotin
antibiotics
source of B9 (folic acid)
diet
vitamin B9 (folic acid) deficiency
meds (tx: give folic acid to counteract): phenytoin sulfonamide TMP MTX malnutrition pregnancy: rapid growth of fetus
complications of B9 (folic acid) deficiency
in utero: neural tube defect (most common cause) growth stage: growth failure child/adult: megaloblastic anemia (need folate for rapidly dividing RBCs) glossitis diarrhea depression confusion megaloblastic anemia
vitamin B12 (cobalamin) deficiency
NEURO sx: parasthesia ataxia (no vibration/position sense) memory loss dementia severe weakness megaloblastic anemia ↓B12 level ↑methylmalonic acid (MMA): needs B12 for metabolism ↑ homocysteine: need B12 for homocysteine → methionine
cause of cavitamin B12 (cobalamin) deficiency
malabsorption of B12 in terminal ileum:
#1) pernicious anemia (autoimmune destruction of gastric parietal cells + IF)
2) gastric bypass (remove part of stomach)
only found in animal
3) chron’s, celiac, enteritis
4) found only in animal products: VEGETARIANS OR VEGANS if no supplementation
absorption of B12 in GI gut occurs
B12-IF in duodenum → absorbed in terminal ileum
treatment of B12 deficiency
oral or IM supplementation if can absorb B12
determining cause of vitamin B12 (cobalamin) deficiency
check for Abs to IF
schilling test: radiolabeled B12 → see how much in urine later on
low: absorption problem
vitamin deficiency with neuro symptoms
vitamin B1: WE
vitamin B6: seizure
vitamin B12: parasthesia, ataxia
used in redox reactions
vitamin B2 (riboflavin) vitamin B3 (niacin)
used in carboxylation reaction
vitamin B7 (biotin) vitamin K
need for DNA synthesis
B9
B12
vegetarians should supplement in diet
B12
