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Clinical Chemistry > Vitamins > Flashcards

Vitamins Flashcards

1
Q

Fat soluble vitamins

A

Vitamins A, D, E, K

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2
Q

Water Soluble Vitamins

A

Vitamins C, B1, B2, B6, B12, folate, biotin, pantothenic acid
niacin

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3
Q

Vitamin A function

A

fat soluble vitamin
binds to cell nuclear receptors
provitamin A (carotene) - structure equivalent of 2 vitamin A molecules

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4
Q

processing of Vitamin A

A

Beta-carotene into retinal & then to retinol (active form) & retinoic acid

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5
Q

transport for Vitamin A

A

retinal binding protein

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6
Q

active form of vitamin A

A

retinol (OH group on the end)

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7
Q

toxic level of vitamin A

A

anything over 100 ug/dl

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8
Q

importance of vitamin A

A

growth, reproduction, immune system
cell differentiation - maintains epithelial integrity
vision- part of rhodopsin

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9
Q

Vitamin A role in vision

A

retinol is oxidized in rods of eye retina to retinal
the complexed w/ opsin to form Rhodopsin
sight in dim light

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10
Q

Vitamin A deficiency

A 
lead to night-blindness- seen in malabsorption, liver impairment, premature infant
loss of hair
joint pain
headaches
drowsiness
vomiting
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11
Q

Hypervitaminosis A

A

vitamin A toxicity > 140 ug/dl in plasma

measured by HPLC

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12
Q

Vitamin E

A

(alpha-tocopherol); anti-oxidant - primary defense against oxidation of unsaturated lipids & cells

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13
Q

Vitamin E metabolism

A

40% absorbed from GI, attaches to chylomicrons for transport to liver
then transported via VLDL to cells
excreted through feces

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14
Q

deficiency of vitamin E

A

shows hemolytic anemia
can see in premature infants, fat malabsorption in adults
measured by HPLC

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15
Q

Vitamin K function

A

(napthoquinone); essential for coagulation factors

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16
Q

Vitamin K dependent coagulation factors

A

II, VII, IX, X also protein C & S

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17
Q

source of vitamin K

A

50% diet & 50% gut bacteria

absorbed into body via bile salts

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18
Q

lack of vitamin K

A

leads to hemorrhagic crisis

usually related to GI malabsorption & antibiotics

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19
Q

testing for vitamin K

A

use Prothrombin time (PT) -extended time

liver disease will also show low coag proteins but may not be vit K related

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20
Q

vitamin K toxicity

A

usually not seen in adults
children with vit K supplement at birth can see increase in bilirbuin
supplements rich in vit K : garlic, gingko, & ginseing

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21
Q

Vitamin D function

A 
1,25 DHCC
facilitates calcium (& phosphorus) absorption
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22
Q

D2

A

ergocalciferol - not naturally occurring

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23
Q

D3

A

cholecalciferol

can make from sunshine on 7-dehydro-cholesterol

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24
Q

vitamin D absorption

A

absorb from gut; attaches to chylomicrons for transport to liver
stored in liver
excreted in bile

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25
Q

vitamin D stimulates

A

ca2+ absorption along w/ phosphorus from intestine
w/ PTH- increases mobilization of ca2+ from bone to circulation
has apoptotic effect - cancerous cells/ loses growth regulation

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26
Q

vitamin D deficiencies

A

children- ricketts
osteomalacia- softening of the bone
AED- hinder vit D absorption
any malabsorption condition or renal issue

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27
Q

vitamin D toxicity

A 
children
hyperparathryoidism
hypophosphatemia
pregnancy 
excess vitD leading to excess calcium deposits in heart & kidneys (damage can be irreversible)
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28
Q

laboratory testing for vitamin D

A

calcium testing - PTH, serum Ca2+, urine Ca2+

assay 25-OH-cholecalciferol or 25-OH vit D3 by immunassay or HPLC

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29
Q

vitamin B1 (thiamine)

A

used to make thiamine pyrophosphate TPP - important coenzyme

needed for decarboxylase subunits of dehydrogenase complexes

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30
Q

vitamin B1 metabolism

A

absorbed through GI

excreted through the kidney; out the urine

31
Q

chronic deficiency of vitamin B1

A

beri beri -wet & dry

seen in underdeveloped countries & alcoholics

32
Q

lab assays for vitamin B1

A

looks at RBC transketolase enzyme activity or ETK before & after thiamine pyrophosphate addition (TPP)
if see >25% increase in ETK after adding TPP, then patient is thiamine deficient

33
Q

vitamin B2 (riboflavin)

A

used to make flavin mononucleotide or FMN & flavin adenine dinucleotide or FAD
coenzymes used in oxidation-reduction reactions (krebs cycle)

34
Q

vitamin B2 absorption

A

absorbed from GI small intestine
stored for 5 months in healthy person
excreted through kidney

35
Q

vitamin B2 toxicity

A

no known toxicity

36
Q

vitamin B2 deficiency

A

seen in alcoholics, chronic diarrhea, malabsorption, drugs: phenothiazine, oral BCP, TCAs
redness & sores

37
Q

lab assays for vitamin B2

A

when glutathione reductase activity is decreased by 40% this indicates riboflavin (b2) deficiency

38
Q

vitamin B6 forms

A

pyridoxine (plant source)
pyridox-amine
pyridoxal (animal sources)
all get converted to PYRIDOXAL-5’-PHOSPHATE

39
Q

vitamin b6 absorption

A

absorbed through the GI tract & excreted through the urine

40
Q

vitamin b6 function

A

used for synthesis, catabolism, & interconversion of amino acids
reactions for metabolism of proteins, lipids, & CHOs
COENZYME FOR AST & ALT!!!

41
Q

lab measure for vitamin b6

A

measures function changes to protein

often looks at homocysteine (!!) in blood & urine

42
Q

vitamin b6 deficiency

A 
usually not alone - other b complex vitamins also deficient
uremic patients (elevated BUN), liver disease,malabsorption, malignancies, alcoholics
associated w/ hyperhomocysteinemia
43
Q

vitamin b6 associated anemia

A

see normo, micro

SIDEROBLASTIC ANEMIA

44
Q

niacin source

A

made from tryptophan as well as dietary intake

hard to be deficient in niacin

45
Q

niacin function

A

combination of nicotinic acid & nicotinamide ; both needed to make NAD & NADP
need these coenzymes for respiration, lipid metabolism, fatty acid metabolism, & glycolysis

46
Q

lab measure of niacin

A

measure NAD & NADP (end products of niacin)

47
Q

niacin absorption

A

absorbed via GI & small intestine

metabolized form out the urine

48
Q

niacin deficiency

A

not usually seen
Pellagra (4Ds) & alcoholics
4Ds= diarrhea, dementia, dermatitis, death

49
Q

niacin toxicity

A

very low, excess niacin leads to decreased lipids, increased flushing, & blood vessel vasodilation

50
Q

Folic acid/folate function

A

necessary for 1-carbon transfers

increased folate needs in pregnancy - helps reduce neural tube defect

51
Q

folic acid/folate absorption

A

closely linked to vit b12
folate absorbed in jejunum w/ intrinsic factor
excess excreted through kidney & out feces
large amount of folate made by colon bacteria & absorbed

52
Q

folate deficiency

A

MEGALOBLASTIC ANEMIA
alcoholism, malabsorption, carcinoma, chronic hemodialysis, hemolytic & sideroblastic anemia
drugs: sulfasalazine, isoniazid, cycloserine, phenytoin, alcohol, oral BCP, methotrexate

53
Q

lab analysis of folate

A

look at serum folate & RBC folate (RBC folate tells about folate stores)
look for increase in serum homocysteine as indicator for folate deficiency

54
Q

vitamin b12 (cobalamin) absorption

A

absorbed from ileum using INTRINSIC FACTOR from stomach, absorbed through mucosal cells, released, bound to new transport protein, goes into plasma to be taken to liver, BM, or tissues for deposit

55
Q

vitamin b12 carrier protein

A 
needs a carrier protein bc it is so large even though it is water soluble
transcobalamin
hydroxycobalamin
methyl cobalamin
deoxyadenosyl-cobalamin
56
Q

vitamin b12 function

A

coenzyme in reactions for hematopoiesis & fatty acid metabolism

57
Q

active form of vit b12

A

methyl cobalamin & dexoyadenosyl-cobalamin

58
Q

vit b12 deficiency

A 
increases w/ age
PERNICIOUS ANEMIA
vegans
FISH TAPE WORM (D. lateum)
malabsorption
antibody to vit b12 -IF complex
59
Q

vit b12 toxicity

A

none known, stays in liver for a decent amount of time (days-months)

60
Q

lab test for vit b12

A

Schilling’s test- radioactive b12
measure serum & urine for radio b12
micro test w/ Lactobacillus leischmanii
immunoassay for vit b12

61
Q

Biotin function

A 
role in gluconeogenesis, lipogenesis, fatty acid synthesis 
role in # of carboxylation reactions: 
pyruvate decarboxylasse
acetyl CoA carboxylase 
etc etc
62
Q

biotin absorption

A

absorbed from small intestine & synthesized by gut bacteria (!)

63
Q

lab assay for biotin

A

chemilumenescent or spectrophotometric methods

64
Q

biotin deficiencies

A

affect the enzymes leading to adverse effects on the skin, pallor, mood & GI
depression & vomiting

65
Q

biotin toxicity

A

not seen

66
Q

pantothenic acid

A

converted to 4’-phosphopantotheinyl moiety which is covalently bound to either serum actyl carrier protein or coenzyme A

67
Q

pantothenic acid source

A

found in many foods making deficiencies extremely rare

68
Q

pantothenic acid deficiency

A

rare - see irritability, constipation, numbness, anorexia, tingling in hands & feet

69
Q

pantothenic acid toxicity

A

not seen

70
Q

pantothenic acid lab analysis

A

lactobacillus plantarium
Pediococcus acidilactici
RIA, GC, HPLC
give PA load & look for metabolite: acetylated-p-aminobenzoic acid in urine

71
Q

vitamin C (ascorbic acid) function

A

strong reducing agent(!!)
important for hydroxylation reactions of proline & lysine to cross link (COLLAGEN SYNTHESIS) & for the conversion of tyrosine to catecholamines (!!!)

72
Q

vitamin C deficiency

A

‘scurvy’/ limey’s disease

hemorrhagic tissues - bleeding gums, impaired wound healing & anemia

73
Q

vitamin C absorption

A

absorbed through GI, distributes in water, excreted via urine
NOT STORED IN BODY

74
Q

lab assays for vitamin C

A

colorimetric method

HPLC- newer

Clinical Chemistry (23 decks)

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