Vitamins I and II Flashcards
(128 cards)
1
Q
Which vitamins are fat soluble?
A
KADE
2
Q
Name 3 vitamins that are made endogenously
A
D, K, niacin
3
Q
T/F- fat soluble vitamins are more easily stored long term than water soluble?
A
true
4
Q
What two things are important for absorption of fat soluble vitamins?
A
bile, pancreatic enzymes
5
Q
List fat malabsorption syndromes.
A
abetalipoproteinemia celiac disease cholestasis inflammatory bowel disease cystic fibrosis gastric bypass surgery Also: use of bile acids or mineral oil
6
Q
T/F- vitamin A is a name given to a group of related compounds, some of which act as hormones
A
true (retinol, retinal, retinoic acid)
7
Q
Name dietary sources of vit A
A
animal: liver, fish, eggs, milk
plant (carotenoids): 6-carotene, yellow/green vegetables
8
Q
where is B-carotene converted to retinol?
A
intestine
9
Q
Where are more than 90% of vitamin A reserves?
A
liver
10
Q
Name 4 biological roles of vitamin A
A
- vision
- cell growth/differentiation (epithelial/keratin)
- metabolic effects of retinoids (bind to nuclear hormone receptors)
- Resistance to infection (mucocilliary/intestinal tract cell differentiation and retinoid immune effects)
11
Q
Earliest manifestation of vitamin A deficiency?
A
reduced night vision
12
Q
Five effects of chronic vitamin A deficiency?
A
- xeropthalmia (dry eye)
- xerosis conjuntivae
- bitot spots (keratin deposits)
- keratomalacia (drying/clouding of cornea)
- blindness
13
Q
Name 3 therapeutic uses of retinoids
A
- severe acne
- psoriasis
- acute promyelocytic leukemia
14
Q
T/F- retinoids aren’t teratogens
A
FAlse. They are! also restrictions on donating blood when taking these because of possibility of getting into a pregnant woman.
15
Q
What is the most common fat-soluble vitamin poisoning in the united states?
A
Vit A
16
Q
Symptoms of vitamin A poisoning?
A
- desquamation
- headache/dizziness/vomiting
- pseudotumor cerebri
17
Q
Chronic excessive vitamin A results in bone resorption and fractures. T/F
A
True
18
Q
T/F- vit D only affects a limited number of organ systems
A
False, it affects nearly every organ system
19
Q
What receptor does it D act on?
A
vitamin D receptor (nuclear hormone receptor)
20
Q
Where does vitamin D2 (ergocalciferol) come from?
A
-plants, fungi, invertebrates
21
Q
where does vitamin D3 (cholecalciferol) come from?
A
endogenous vitamin D in animals
22
Q
What is the main storage form of vitamin D and is best for assessing vitamin D nutritional status?
A
25-hydroxyvitamin D (calcidiol)
23
Q
What is the most biologically active form of vitamin D?
A
1,25 dihydroxyvitamin D (calcitriol)
24
Q
T/F- calcitriol controls expresssion of 200 genes, is expressed in the brain, prostate, breast, colon and other tissues, and some cancers can convert calcidiol to calcitriol
A
true
25
T/F- vitamin D cannot be used for psoriasis or auto-immune diseases
False, it can be
26
What role does sunlight play in endogenous synthesis of vit D?
UVB converts 7-dehydrocholesterol to previtamin D3, which rapidly converts to D3.
Not active if UV index less than 3
27
Can you get vit D toxicity from too much sun?
no, excess previtamin D3 destroyed by sunlight
28
What are some exogenous sources of vitamin D?
oily fish, eggs, milk, dietary supplements
29
Where is vitamin D metabolized to 25-OH?
liver
30
where is 25 OH converted to 1,25 dihydroxy vit D?
kidney
31
what regulates conversion to 1,25 dihydroxy vitamin D3?
PTH, serum Ca, phosphate
32
T/F- vitamin D increases absorption of intestinal Ca and Phosphorus as well as renal Ca absorption
true
33
What is a problem with renal failure regarding vit D?
decreased conversion to 1,25 dihydroxy vit d
34
T/F- vit d deficiency is rare
False, it is common and increases risk of fractures, osteomalacia, rickets etc.
35
Vitamin D deficiency is associated with what cancers?
colon, pancreas, breast, ovary, Hodgkins lymphoma
36
T/F- 1,25 dihydroxy is a potent immunomodulator
true. For example, monocytes/macrophages up regulate VDR in response to tuberculosis infection
37
T/F- increased 25-OH vit D is associated with lower multiple sclerosis risk
true
38
Name 7 causes of Vit D deficiency
Sunscreen, aging (reduced 7-dehydrocholesterol), skin damage (burns), poor diet (remember that human breast milk contains very low vitamin D!), liver failure (can't make 25-OH), renal failure, heritable disorders
39
How do you treat vitamin D deficiency?
- 200 IU children and adults <50 yrs
- 1000 IU/day if no sun exposure
- 50,000 IU as a bolus injection
- sunlight/UV radiation
40
Should you check 1,25 dihydroxy vit D levels for nutritional status?
no
41
What are 3 debates for vitamin D in healthcare?
1. payors not reimbursing vitamin D testing in many populations
2. concerns of over aggressive supplementation
3. where to set reference ranges
42
At UIHC, what age group gets most vitamin D testing?
around 60, more commonly females
43
What is the major form of vitamin E?
alpha-tocapherol
44
What are dietary sources of vitamin E?
vegetable oils, peanuts
45
What is a common reason for deficiency?
diet deficient in leafy green vegetables
46
What is the main biological function of vitamin E?
anti-oxidant (also thought to preserve neurological function)
47
Is vitamin E deficiency common or rare in U.S.?
rare
48
What conditions can lead to vitamin E deficiency?
cholestasis, pancreatitis, cystic fibrosis, abetalipoproteinemia
49
What are signs of vitamin E deficiency?
neurologic (ataxia, neuropathy), hemolytic anemia (infants)
50
Is vitamin E toxicity a common problem?
no, its rare
51
What are complications of vitamin E toxicity?
coagulopathy, decreased wound healing. infants given too much vit E have higher incidence of sepsis and necrotizing entercolitis
52
Where is vitamin K1 (phylloquinone) found?
plants! cabbage, cauliflower, spinach. also in pork, liver, soybeans, vegetable oils. Low amounts in breast milk
53
Where is vitamin K2 found or produced?
produced in intestinal tract by gram positive bacteria
54
Is k3 (synthetic) still used in the united states?
no
55
What lipid soluble vitamin does the body hold the shortest reserve of? How long is it?
vitamin K, 3 week reserve
56
Name 2 biological functions f vitamin K
1. required for gamma-carboxylation of glutamate side chains of some clotting factors (II, VII, IX, X, C, S)
2. modified glutamic acid residues (gamma-carboxyglutamic acid binds calcium, allowing cross-bridge with phospholipids
57
Symptom of vitamin K
| deficiency?
usually hemorrhage (ecchymosis, epistaxis, intestinal bleeding)
58
What age group is at particularly high risk and routinely given vit K?
infants (intestinal flora not developed to make vitamin K2, breast milk low in vitamin K)
59
Warfarin blocks what enzyme?
VKOR (mutations in VKOR can cause resistance)
60
What is an overdose of warfarin treated with?
vitamin K and/or fresh frozen plasma (provides clotting factors)
61
T/F- vitamin K toxicity is rare but associated with hemolytic anemia in infants
true
62
T/F- cystic fibrosis is likely associated with combined deficiency of vitamins ADEK?
true
63
What would be an appropriate indication for 1,25 dihydroxy vitamin D plasma level test?
renal failure with persistent hypocalcemia
64
Is vitamin C synthesized endogenously in humans?
no
65
Name 3 biological functions of vitamin C
anti-oxidant, improves absorption of non-heme dietary iron, and involved in multiple biochemical pathways
(involved in hydroxylation of pro collagen to collagen)
66
Is vitamin C deficiency rare or common in USA?
rare (scurvy)
67
What populations are at risk for vitamin C deficiency?
elderly, those on restricted diets, alcoholics
68
Symptoms of scurvy?
- perifollicular hemorrhage
- coiled body hairs
- ecchymoses
- xerosis (dry skin)
- poor wound healing
- gum abnormalities
69
Problems with vitamin C toxicity?
high doses acidify urine and promote iron overload in pts with thalassemia and hematochromatosis. DOES NOT CAUSE KIDNEY STONES
70
What is another name for vitamin B1?
thiamine
71
Is B1 water soluble?
yes
72
What foods is B1 found in?
yeast, grains, peas, potatoes, vegetables
73
T/F- B1 is leached out of food after being washed or boiled
true
74
T/F- B1 is transported in plasma as thiamine and phosphorylated in tissue
true
75
What is the purpose of Thiamine triphosphate (TTP)?
involved in nerve conduction (Na+ channels)
76
What is the purpose of thiamine pyrophosphate (TPP)?
carbohydrate pathways, branched chain amino acids
77
Name the symptoms of thiamine deficiency in infants
dyspnea, cyanosis, diarrhea, vomiting, wasting
78
What populations is thiamine deficiency common in? What does this cause?
- Elderly and alcoholics
- Dry beriberi: poor appetite, fatigue, peripheral neuritis
- Wet beriberi: edema and cardiac failure
79
What populations is Wernicke Korsakoff syndrome common in?
alcohoilics, AIDS
| -exacerbated by magnesium deficiency
80
Compare wernicke encephalopathy to korsakoff syndrome
- wernicke encephalopathy: confusion, ataxia, opthalmoplegia
| - Korsakoff syndrome: short term memory loss, confabulation (spontaneous narration of events that never happened.
81
Is thiamine toxicity common?
No but it can cause headache, convulsions, cardiac arrhythmias, and neuromuscular collapse when it does happen
82
What is vitamin B2 known as?
riboflavin
83
What are the cofactor forms of B2 (riboflavin)?
flavin mononucleotide (FMN) and flavin adenine nucleotide (FAD)
84
What foods are high in B2?
milk, liver, eggs, vegetables
85
Is B2 stable to heat?
yes
86
Does B2 degrade in milk if exposed to light?
yes
87
What are the biological functions of riboflavin (B2)?
- cofactors for large group of flavoproteins
- flavoproteins funciton in redox rxns (respiratory enzymes, iron metabolism, pyridoxine metabolism, folate metabolism, xenobiotic detoxification)
88
What two factors put people at risk for riboflavin (B2) deficiency?
poverty and poor diet
89
What are symptoms of riboflavin deficiency?
angular stomatitis, glossitis, photophobia, blepharospasm, dermatological changes, neurological changes (behavior, neuropathy, EEG changes)
90
Is riboflavin toxicity common?
NO, very rare, little evidence for distinct overdose syndrome
91
What is vitamin B3 also known as?
niacin
92
B3 (niacin) is a derivative of what?
pyridine
93
B3 deficiency is associated with what?
poor diet
94
What are the active cofactor forms of B3?
NAD and NADP
95
Can NAD and NADP be made from anything beside B3?
yes, tryptophan
96
Name the 3 D's associated with Niacin deficiency (pellagra)?
-diarrhea, dermatitis (+glossitis, stomatitis), dementia
97
T/F- carcinoid tumors can predispose to niacin deficiency due to accelerate tryptophan metabolism
true
98
T/F- gram doses of niacin used for lipid disorders can cause flushing, wheezing, headache, GI discomfort, liver toxicity
true (can premedicate with aspirin/NSAIDs to prevent these effects)
99
What enzymes should you monitor for someone on high dose niacin therapy?
liver enzymes
100
What is B6 also known as?
pyridoxine
101
What are dietary sources of B6?
meats, vegetables
102
What two liver enzymes is B6 important for synthesizing?
ALT/AST
103
T/F- B6 is needed for the conversion of tryptophan to serotonin or to niacin
true
104
Symptoms of vitamin B6 deficiency in infants?
-irritability, seizure, anemia, vomiting, ataxia, abdominal pain
105
Symptoms of B6 deficiency in adults? Predisposing factors?
- Sx: facial seborrhea, peripheral neuropathy
| - Predisposing factors: celiac disease, ulcerative colitis, lactation, alcoholism
106
T/F- pyridoxine deficiency in pregnant women associated with poor birth outcomes?
true
107
What drugs antagonize pyridoxine?
isoniazid, corticosteroids, penicillamine
108
Symptoms of B6 toxicity?
RARE-tachypnea and neuropathy
109
Name 2 therapeutic uses of B6
- hyperemesis gravidarum (nausea and vomiting in pregnancy)
| - seizure control in early childhood (only vitamin deficiency linked to seizures)
110
What is B12 also called?
cobalamin
111
Dietary sources of cobalamin?
meat (liver), dairy
112
T/F- B12 deficiency is rare in vegetarians
False. 2/3 of vegetarians have deficiency
113
What is pernicious anemia?
autoimmune disorder with gastric atrophy and decreased/absent intrinsic factor
114
Where does B12/IF absorption occur?
ileum
115
What is b12 carried in the plasma by?
transcobalamins
116
What 2 biochemical reactions require B12?
1. conversion of methylTHF to TFH
- >secondarily converts homocysteine to methionine
2. methylmalonyl-CoA to Succinyl-CoA
117
How long to become deficient in B12?
2-4 years
118
Does B12 have low or high toxicity?
very low toxicity
119
Folic acid is vitamin precursor to what?
tetrahydrofolate
120
Source of folate in diet?
liver and green vegetables, breads and grains now supplemented
121
Are folates absorbed as mono or polyglutamates?
converted to monoglutamates in the gut and absorbed in the ileum then converted to polyglutamates in tissues
122
Functional activation of folic acid requires what?
B12
123
Examples of folate antagonists?
trimethoprim and methotrexate
124
What do folate antagonists inhibit?
TFH reductase
125
Who should be supplemented with folate?
pregnant women, premature infants, and patients with chronic hemolysis
126
T/F- cyanocobalamin (B12) can only be given separately as intramuscular injection
true
127
What is a caution about multivitamins?
possibility of vitamin A toxicity and on patients with warfarin (vitamin K reduces effectiveness)
128
Most common vitamin deficiency in a strict vegetarian who doesn't eat eggs?
B12
