vitamins Flashcards
functions of vitamin A
antioxidant
specialized epithelium
vision
vit A used in the treatment of (2)
measles
AML M3
symptoms of vit A deficiency
first- night blindness
also corneal ulcerations, dry skin
symptoms of vit A excess (4)
increased ICP/pseudotumor
bone/joint pain
hair loss
hepatitis
teratogenic effects of excess vitamin A
cleft palate, cardiac abnormalities
vitamin B1
thiamine
TPP is a cofactor for (4)
pyruvate dehydrogenase complex
a-ketoglutarate dehydrogenase complex
transketolase
branched-chain amino acid dehydrogenase
thiamine deficiency
impaired glucose metabolism, results in beriberi and WK
dry beriberi
peripheral neuropathy, muscle wasting
wet beriberi
high output heart failure
edema
areas of brain damaged in WK
MD of thalamus
mammillary bodies
treatment of hypoglycemia in alcoholic patients
always give thiamine first, giving glucose without thiamine in a thiamine deficient patient can precipitate wernike’s
vitamin B2
riboflavin
reactions that riboflavin is involved in
oxidation/reduction
FMN
NADH dehydrogenase (complex I)
FAD
succinate dehydrogenase (complex II)
riboflavin deficiency
cheilosis, corneal vascularization
population that is at increased risk for riboflavin deficiency
neonates getting phototherapy (B2 degraded)
vitamin B3
niacin
amino acid from which niacin is derived, cofactor
tryptophan
B6 cofactor
niacin deficiency
pellagra- diarrhea, dermatitis, dementia
2 diseases that can cause niacin deficiency
hartnup disease (decreased tryptophan absorption) and carcinoid syndrome (increased tryptophan consumption for serotonin synthesis)
vitamin B5
pantothenate
B5 is a part of
CoA for acyl transfers and FA synthase
unique symptom of B5 deficiency
adrenal insufficiency (due to decreased FA synthase activity)
vitamin B6
pyridoxine
3 general reactions B6 is needed for
amino acid synthesis
heme synthesis
transamination
B6 deficiency (3)
peripheral neuropathy - dec NTs
sideroblastic anemia - dec heme
convulsions- dec GABA
vitamin B7
biotin
type of reaction that requires biotin
carboxylation (adding 1C)
biotin deficiency
rare, related to raw egg white ingestion (avidin)- dermatitis, alopecia
vitamin B9
folic acid
main use of B9
purine/thymine synthesis- 1C transfers
folate deficiency (2)
megaloblastic anemia
no neuropathy
*most common bit def in USA
deficiency in pregnancy
neural tube defects
b12 is a cofactor for (2)
- homocysteine methyltransferase (homocysteine –> methionine)
- methylmalonyl-CoA mutase (methylmalonyl-coa –> succinyl-CoA)
b12 deficiency symptom classes (2)
- megaloblastic anemia
- peripheral neruopathy
why does B12 def cause megaloblastic anemia?
decreased homocysteine methyltransferase activity leads to decreased conversion of homocysteine to methionine = decreased THF = decreased dTMP pyrimidines
why does B12 deficiency cause peripheral neuropathy?
increased methylmalonyl-CoA leads to defects in myelin
schilling test
determine etiology of B12 deficiency, test B12 in urine (decreased B12 in urine indicates decreased absorption)
infection that can cause B12 deficiency
diphyllobothrium latum
general causes of B12 deficiency (3)
malabsorption
lack of IF
terminal ileum disease
what is SAM?
product of methionine + ATP
what is the role of SAM?
transfers methyl units
what reaction is dependent on SAM?
conversion of norepinephrine to epinephrine
role of vitamin C in collagen synthesis
cofactor for the hydroxylation of lysine and proline residues
excess vitamin C increases the risk of toxicity from what metal? why?
iron toxicity, because it C puts iron in 2+ state making it more readily absorbed
sites of hydroxylation for vitamin D
liver 25-OH
kidney- 1-OH
why is hypercalcemia seen in sarcoidosis?
activated macrophages in granulomas increase vitamin D activation
another name for vitamin E
a-tocopherol
main role of vit E
antioxidant
vit E deficiency
hemolysis and posterior column/spinocerebellar tract degeneration (mimics B12 but low MCV)
role of vit K
catalyzes gamma carboxylation of clotting factors 2, 7, 9, 10, proteins C and S
patients at risk for it K deficiency
neonates (no flora)
long term abx (depleted flora)
what can decrease vit K in breast milk
antibiotics taken by mother, especially cephalosporins
symptoms of zinc deficiency (4)
rash around face, mouth
delayed wound healing
abnormal sense of smell
infertility in males
