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Clinical Chemistry II - 4378 > Vitamins > Flashcards

Vitamins Flashcards

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1
Q

Vitamin Deficiencies

A

result from inadequate supply

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2
Q

Vitamin Insufficiencies or vitamin Dependencies result from

A

result from abnormal
metabolism with an adequate supply

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3
Q

Vitamin toxicity ( Fat soluble) can result if

A

can result if over-ingested

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4
Q

Vitamins physiological functions

A
  • Serve primarily as cofactors of enzymatic
    reactions in body
  • Some function as hormones (Vit A & D)
  • Some function as transcription regulators (Vit A)
    ** Must be obtained from external sources
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5
Q

Vitamins that serve as transcription factors

A

Vitamin A

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6
Q

Vitamins that serve as hormones

A

Vit A and D

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7
Q

Vitamins metabolism

A

1.Reduced serum levels may not indicate a
deficiency that interrupts cellular function
2.Normal values may not reflect adequate function
2A) Clinical expression of Vit abnormalities
2B) Clinical symptoms of Vit deficiencies: nonspecific
in early as well as in mild chronic stages
➡ Deficiencies difficult to diagnose initially

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8
Q

Fat soluble vitamins

A

A, E, D, K

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9
Q

Water soluble vitamins

A

B vitamins: thiamine, riboflavin,
niacin, B6, B12,
folate, pyridoxine,
pantothenic acid &
others
➢Biotin
➢Vitamin C
➢Carnitine

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10
Q

Laboratory measurements of vitamins

A

➢ vitamin precursors
➢ vitamin
➢ vitamin metabolites
➢ some biochemical function with and
without vitamin (Schilling, etc.)
Blood (serum/plasma) or urine
* Immunoassay, HPLC, CPB

  • RIA, MEIA, and FPIA
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11
Q

Immunoassays of vitamins

A

HPLC, CPB

RIA, MEIA, FPIA

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12
Q

FAT soluble vitamins

types

Absorbed as part of

what must be present for Absorption

what conditions are they deficient

A

-A,D,E,K
-Absorbed as part of the chylomicron
* Fat must be present for absorption
* Chronic malabsorptive states

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13
Q

Fat soluble Vitamins come from what sources and where are they stored

A

Dietary sources
animal & plant products—varies with
vitamin
Stored in liver and fat tissue

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14
Q

Deficiencies of fat soluble vitamins

Vitamin A, E, and D+K storage

May be difficult to

A

Deficiencies: develop slowly
- Vit A storage: 1 year
- Vit E storage: several months
- Vit D & K: storage days or weeks

may be difficult to diagnose; vague symptoms

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15
Q

Fat soluble vitamins disorders

A

Bile and pancreatic function,
bowel mucosa
mpaired bile flow,
* Pancreatic disease
* Chronic bowel inflammatory conditions
* Fistula
* Small bowel obstruction
* Alcohol liver disease
* Cryptosporidium infection

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16
Q

New acquired form of lipid soluble vit deficiency

  • A,D,E,K
A

✴ Lipase inhibitor: Xenical
✴ Ingestion of non-bioavailable fat substitutes: Olester
✴ Patient after bilopancreatic diversion for obesity

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17
Q

Water soluble vitamins

At least how many water soluble vitamins

Moderate excess intake is

Most are stored for

Deficiencies develop more rapid then

A
  • At least 9 water soluble vitamins
  • Moderate excess intake is almost immediately excreted in the urine
  • Most are stored for <2 months
    ➢Deficiencies develop more rapidly than fat soluble vitamin
    deficiencies
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18
Q

Exceptions is vitamin

A

-B-12
-can be stored in the liver for up to 12 months.

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19
Q

Vitamin A

has how many active forms and what are there names
* Derived from dietary carotenoids (β-carotene)

A

Three biologically active forms
➢Retinol, Retinal, Retinoic acid

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20
Q

Vitamin A dietary source

A

➢animal and plant
➢butter, al-livcream, whole milk, whole milk
cheeses, egg yolk
➢dark green leafy vegetables, yellow vegetables,
yellow fruit & fortified margarine

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21
Q

Retinol is carried by

A

Chylomicrons in the lymphatics to the liver where retinol binds to RBP and pre-Albumin

Retinol + RBP/ Pre-albumin attaches to RBP-receptor and allows Retinol + cRBP into the cell.

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22
Q

Functions of vitamin A

A

➢Vision (most clearly defined role)
➢Growth
➢Reproduction
➢Mucus secretion
➢Immune system functions
➢Epithelial cell development, differentiation,
regulation.

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23
Q

Vitamin E: Tocopherol has several isomers but

A

a form is most studied

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24
Q

Vitamin E: Tocopherol dietary sources

A

➢Vegetables oils
➢Wheat germ, rice germ,
➢Leafy green vegetables,
➢Legumes & nuts
* Transported: w/ chylomicrons &
VLDL (aTTP)
* Stored primarily in adipose tissue

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25
Q

Vitamin E: Tocopherol functions

A

➢Antioxidant
➢Protects cell membrane (RBC) from
oxidation of lipids in the membrane.
➢Therapeutically to prevent hemolytic
anemia. (premature newborns)
➢Anti-aging, cardio and neuro protection

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26
Q

Vitamin K: hydroquinone
has several structures and they are

A

K1, K2, K3

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27
Q

Vitamin K Dietary sources

A

➢cabbage, cauliflower, green leaves of
alfalfa, spinach, liver, soy beans and
vegetable oil.
➢Intestinal bacteria
–> 50% from each source
*Absorption is with chylomicrons

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28
Q

Vitamin K (hydroquinone) functions

A
  • Normal coagulation
    ➢Required for synthesis of Factor II, VII, IX,
    X, protein C & S
    ✓Acts as a cofactor in Vit-K dependent
    carboxylation of glutamic acid
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29
Q

Vitamin K1 is

A

Phylloquinone

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30
Q

Vitamin K2

A

Menaquinone-4

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31
Q

Vitamin K3

A

Menadione

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32
Q

Two forms of Vit D

A

Vitamin D3= cholecalciferol
Vitamin D2= Calciferol

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33
Q

Vitamin D3

A

➢Produced in skin from UV
activation of 7-dehydrocholesterol
➢Prohormone converted by liver to calcidiol
à hydroxylated to calcitriol (active form

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34
Q

Vitamin D2

A

*Vit D 2 : calciferol (dietary form)
➢Hydroxylated to calcitriol in the same way as D

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35
Q

Dietary sources of Vitamin D

A

➢Fish liver oil
➢Fortified milk
➢Irradiated foods
( Ionizing Radiation)
➢Smaller amounts in butter, egg yolk, liver, certain fish (esp. salmon and sardin

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36
Q

Vitamin D functions

A

➢Calcitriol enhances Ca2+ uptake from the GI and increases the release of Ca2+ from
bone into blood

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37
Q

Vitamin A deficiency lead to

A

Decreased vision and Decreased Immune system function

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38
Q

Vitamin A toxicity
—> upon what

symptoms

A

Upon overdose
❑ Symptoms:
* Dermatologic disorders
* Bone pain
* Renal disorders
* Intracranial
hypertension
* Hemorrhage
* Teratogen

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39
Q

Total Vitamin A assay

Retinol(RBP) assay

B-Carotene

A
  • Total Vit A:
    ➡Fluorometry or HPLC
  • Retinol (RBP):
    ➡Immunoassay
  • β-Carotene:
    ➡Extraction of β-carotene,
  • measure directly @ 450 nm
    ** Light sensitive
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40
Q

Vitamin E Deficiency

A
  • Rare
  • Neurological signs
    - Ataxia
    - Peripheral neuropathy
  • Macrocytic megaloblastic Anemia
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41
Q

Vitamin E Assay

A
  • HPLC
  • GC-IDMS
  • Photometry or Fluorimetry
  • TLCG
    à separate tocopherols &
    tocotrienols.
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42
Q

Vitamin E assay reaction

A

Tocopherol + FeCl3
—–> Tocopheryl quinine + Fe2+ + a,a-dipyridyl [ Red].

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43
Q

Vitamin K deficiency

A
  • ~ 3 weeks to develop
  • Hemorrhage secondary to reduced
    prothrombin and other coagulation factors
  • ecchymoses, epitaxis, intestinal
    hemorrhage
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44
Q

Vitamin K Assay

A
  • Seldom measured directly
  • PT & APTT
    à Both will be prolonged in a deficiency,
    but thrombin time will be normal
  • Direct measurement:
    immunoassay or HPLC (rare)
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45
Q

Vitamin D deficiency

A
  • bone malformations
    –> à Rickets in children and osteomalacia in adults
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46
Q

Vitamin D Assays

A
  • Immunoassay
  • HPLC
  • LC with Mass Spec (LCMS)
    ** Normal values still being debated
  • <50 nmol/L considered low
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47
Q

water soluble vitamins

A

Vitamin C and B

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48
Q

Vitamin C

-Distributed throughout what

  • Deficiency may take several blank to
  • High concentrations in
  • Excreted in urine as blank
A
  • Distributed throughout tissues
  • Deficiency may take several months to develop symptoms
  • High concentration in CSF
  • Excreted in urine as oxalate
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49
Q

Plasma Vitamin C concentration is lower then

A

CSF

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50
Q

Oxalate is the metabolite of

A

Oxalate is the metabolite of Vitamin C –~50% of urinary oxalate is from
Vitamin C

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51
Q

Ascorbic Acid dietary sources

A

-Found primarily in citrus fruits & vegetables: oranges, lemons, limes,
tomatoes, grapefruit
- Other vegetables and fruits: green peppers, broccoli, leafy green vegetables, potatoes,
strawberries
-Heat and oxygen labile

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52
Q

Vitamin C is high in what foods

A

found primarily in citrus fruits & vegetables: oranges, lemons, limes,
tomatoes, grapefruit

Highest in those foods when they are fresh & uncooked

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53
Q

Many plants and animals can synthesize what but humans cant

A

Plants and many other animals can synthesize Vitamin C, but humans cannot—
must be ingested.
Protein and glucose ?

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54
Q

Vitamin C- Functions

A
  1. Functions as an electron transfer molecule for enzymes involved in
    collagen formation and stabilization
  2. Antioxidant
  3. Involved in catecholamine synthesis
  4. Cholesterol metabolism
  5. Synthesis: Carnitine, Steroid
  6. Uptake of non-heme iron
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55
Q

Vitamin C function in Collagen and formation and stabilization

A

via hydroxylation of proline & lysine which are required to allow the formation of the triple helix and
the cross linking of the collagen chains). (Most well-described function and clinically demonstrated
in the Scurvy which is a disease of impaired cllagen synthesi

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56
Q

Vitamin C roll in Catecholamine synthesis and what type of vitamin C is involved

A

tyrosine conversion to the catecholamines
via dopamine β-hydroxylase. Adrenal
(medulla) have much higher concentration
of Vit C

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57
Q

Vitamin C involvement in Uptake of non-heme iron

A

in the gut is facilitated by asobic acid through the
nonenzymatic reduction of Fe 3+ to Fe2+

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58
Q

Vitamin C- Deficiency

It may take how many months to develop

A

Vitamin C is distributed throughout tissues, a deficiency may take several months to exhibit
symptoms.

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59
Q

Vitamin C deficiency can result in

A

Deficiency results in SCURVY
Impaired collagen synthesis

Breakdown of connective tissues
-Gum and tooth
disease
-Bone disease
-Poor wound healing

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60
Q

Vitamin C symptoms

A
  • weakness, irritability, pains in joints/muscles
  • Bleeding into skin, GI tract & urinary tract
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61
Q

Vitamin C plasma value

A

less then 13 micro meters

62
Q

Vitamin C assays

A
  • HPLC is currently the predominant laboratory method.
  • Both serum & leukocyte assays available
63
Q

What vitamin C assay is the best

A

Leukocyte assay is probably Best

Because of limited stability of ascorbic acid in plasma and serum (better in whole blood).
After only 1 day at room temp, serum ascorbic acid measurements are significantly
diminished and are undetectable by the day 2. Similarly, serum stored at 4 ºC shows
significant decreases in ascorbic acid levels after 3-5 days.

—> serum and plasma measurements do not correlate very well with tissue vitamin C
levels.

64
Q

Vitamin C

what levels vary

A
  • Serum levels vary
  • There is an inter laboratory variability with an average CV of 15% across multiple studies. This
    variability is most likely related to differences in the differential detection of the many ascorbic
    acid isomers/metabolites
65
Q

Vitamin C amount associated with scurvy

A

less then 0.24 mg/dl associated with scurvy
greater them 0.14 mg/dl will be cleared by the kidneys

66
Q

Vitamin B2

what the name

is what color vitamin

what are activators

A

Riboflavin

  • Yellow-pigmented vitamin
  • FMN, FAD + are activators
67
Q

Vitamin B2 functions

A

– Serves as a cofactor in a variety of oxidative reactions:
Fatty acid oxidation
TCA cycle reactions
Oxidative phosphorylation in the respiratory chain
– Important in metabolism of iron, pyridoxine, and folic acid
– May help protect from oxidants

68
Q

Vitamin B2 Dietary Sources

A

➢ Found in milk
➢ Organ meats, such as liver
➢ Other meats,
➢ Leafy green vegetables

69
Q

Riboflavin deficiencies result in

A

Dermatologic changes
Mouth lesions
Glossitis (smooth tongue)
Eyelid spasms & conjunctival congestions
Hematologic dyscrasias

70
Q

Riboflavins better measurement

A
  • Measurement of RBC riboflavins & flavins
  • (FMN, FAD) are better than serum
71
Q

Riboflavin and its two cofactor active forms are

A

Riboflavin and its two cofactor-active forms riboflavin 5’ phosphate mononucleotide (FMN) and
flavin adenine dinucleotide (FAD +) (ßthe most water soluble) exhibit fluorescence.
* FAD + is orange fluorescence;
* Riboflavin & Riboflavin 5’ phsophate fluoresce yellow-gre

72
Q

Riboflavin has what activity in RBCs

A
  • Glutathione reductase activity (coefficient) in RBC (EGRAC)
73
Q

Pyridoxine

Group of compounds are structurally related to

A

Group of compounds structurally related to pyridoxal phosphate (P5P, PLP)

74
Q

Riboflavin is what number of B vitamin

A

Vitamin B2

75
Q

Functions of Pyridoxine

A
  • Important co-factors for catalysts in transamination (transferase) and
    decarboxylation of amino acids
  • Active in > 60 enzyme systems
76
Q

Pyridoxine Dietary sources

A

-Primarily in meat, poultry, fish
-Also in sweet potatoes
-Other vegetables

77
Q

Best known function of the pyridoxine cofactors are

A

Best known functions of the pyridoxine cofactors
are their roles in the conversion of tryptophan
to serotonin, tryptophan to nicotinic acid and
metabolites (niacin)

78
Q

Pyridoxine deficiencies

symptoms are

A
  • Weakness
  • Abdominal pain, vomiting
  • Seizures
79
Q

Pyridoxine: Deficiencies

Conditions associated with deficiencies include

A

-Alcoholism
-Pregnancy
-Certain drug therapies: Ca ++ channel blockers, oral contraceptives,
isoniazid, steroids, penicillamine

80
Q

Pyridoxine: Deficiencies

Measurements is usually by what

A

HPLC

81
Q

Niacin ( nicotinic acid)
Function

A

Coenzyme
The active cofactor forms: collectively called the ‘pyridine nucleotides’
Niacin is a component of the coenzymes NAD+ & NADP+
NAD + & NADP+: involved in oxidation-reduction reactions
Example: glutamate dehydrogenase, LDH & G6PDH

82
Q

Pyridoxine is what B vitamin

A

vitamin B6

83
Q

Niacin( Nicotinic acids) are involved in what type of reactions

A

NAD + & NADP+: involved in oxidation-reduction reactions

Example: glutamate dehydrogenase, LDH & G6PDH

84
Q

Niacin (nicotinic acid) Dietary source

A

-Meats, poultry, fish
-Grains (except corn), esp. whole grains
-Flours, cereals
-Nuts, legumes
-Anything rich in tryptophane is typically a good source of niacin
–NAD + & NADP+ can also be synthesized from liver tryptophane

85
Q

NAD and NADP can also be synthesized from

A

The liver

86
Q

-Anything rich in tryptophane is typically a good source of

A

Niacin

87
Q

Niacin Deficiency

causes what condition

Early symption

A
  • Niacin deficiency causes a condition called “pellagra”
  • Early symptoms include lethargy, anorexia, weakness, digestive disturbances,
    weight loss, dermatitis
88
Q

Niacin - Deficiency

Late symptoms

and Pellagra is characterized by

A
  • Late symptoms include mucus membrane inflammation
    à Result in diarrhea, urethritis and vaginitis
    à Mental disturbances with disorientation
    ** Pellagra is sometimes hallmarked by the ‘3 D’s—Diarrhea, Dermatitis, Dementia
89
Q

Niacin Toxicity

A
  • Symptoms of toxicity include:
    Cutaneous flushing, gastric irritation, liver dysfunction with jaundice, hyper uricemia,
    impaired glucose tolerance
  • Niacin is sometimes prescribed in high doses to treat elevated LDL cholesterol
90
Q

Niacin is what number of B vitamin

A

Vitamin B3

91
Q

Thiamine function and number of B vitamin

A

B1

  • Function:
    –As thiamine pyrophosphate, it is a cofactor in enzymatic decarboxylation of
    ketoacids in the formation of ketols
    –Major carbohydrate pathways
    –Metabolism of branched chain amino acid
92
Q

How does Thiamine function in the Carbohydrate pathway

A

Pyr—> Acetyl CoA

93
Q

Thiamine Dietary sources

A

–Yeast, wheat, whole grain and enriched breads, cereals
* Highly water soluble & easily leached from foodstuffs during washing or
boiling

94
Q

Thiamine deficiency

symptoms

A

Alcoholic & Elderly

  • anorexia, alcoholism, vomiting & diarrhea, edema, cardiac failure
    —> Mg ++ deficiency(alcoholism): impairs thiamine activation
    —-> Associated with poor appetite, fatigues and peripheral neuritis
95
Q

Thiamine is associated with what type of people

A
  • elderly adults with psychiatric disorders
96
Q

Thiamine deficiency

what type of therapy

A

(Loop Diuretic –elderly adults take this sometimes)

97
Q

Servere Deficiency of Thiamine presents as a what

A

neuropathy (beriberi)

-Wet [heart & circulatory system]
-Dry [neuronal damage]
–> loss of muscle strength
—> eventually muscle paralysis

98
Q

Biotin is part of the

Biotin is what sensitive and poorly what

A
  • Biotin is part of the B complex (B7 )
    ** Biotin is heat sensitive and poorly soluble in water
99
Q

Biotin acts as

A
  • Acts as a coenzyme in pathways of gluconeogenesis, FA synthesis and AA
    metabolism

coenzyme for carboxylation & carboxyl group exchange

100
Q

enzymes that rely on Biotin

A

acetyl CoA, propionyl CoA, pyruvate carboxylase, methyl malonyl
oxaloacetic transcarboxylase (Impt as coenzymes in some of these enzyme rxns/activities)

101
Q

Biotin is inhibited by

A

Inhibited by raw egg whites in diet (binds to avidin in egg whites)

102
Q

Biotin dietary sources

A

Found in many foods, especially liver and other organ meats, kidney, milk, egg yolk,
yeast, nuts, legumes

103
Q

Biotin deficiencies

A

✦ Dermatitis
✦ Neurologic changes, mental changes
✦ Nausea & anorexia
✦ Alopecia: autoimmune skin disease
✦ Impaired immunity
✦ Anemia
✦ Peripheral vasoconstriction
✦ Coronary ischemia

104
Q

Biotin Deficiencies

Autoimmune skin disease that leads to hair loss

A

Alopecia

105
Q

Pantothenic acid (B3/B5)

Essential what

Involved in what types of metabolism

A
  • Essential growth factor
  • Involved in fatty acid metabolism
106
Q

Metabolically, pantothenic acid is converted to what

A

4-p-pantothenine which is bound to coenzyme A
or another acyl carrier protein. CoA complex functions like ”acyl group transfer
enzyme” (COO- )

107
Q

Pantothenic Acid (B3/B5)

Dietary sources

A

liver & other organ meats, milk, eggs, fish (especially salmon), peanuts and other
legumes, mushrooms, whole grains

108
Q

Pantothenic Acid (B3/B5)

what is not known

A

Pantothenic acid deficiency has been induced experimentally and signs of deficiency include
apathy, depression, increased infections, burning sensations, and muscle weak

109
Q

Vitamin B12 and Folate

how do they interact and assayed

A

Vit B 12 and folate interact
metabolically
à a deficiency in either results
in megaloblastic anemia

110
Q

Vitamin B12 functions

A

synthesis of
folate

111
Q

Vitamin B12:

name

is what structure

A

Cobalamin

Vit B 12 is a tetrapyrrol ring structure with a central cobalt atom

112
Q

Vitamin B12: Cobalamin

Functions

A
  1. Important in hematopoiesis
  2. Acts as an adenosyl cobalamin (Coenzyme B12),
    functions in the formation of CNS myelin sheath
  3. Amino acid synthesis
    esp. branched-chain ketoacid metabolism
  4. Folate synthesis
113
Q

Folate synthesis is required for

A

Required for synthesis of Purine & Pyrimidine needed for DNA synthesis

114
Q

Vit B 12 : Cobalamin

Dietary sources

how is vitamin B12 absorbed

Vitamin B12 type one one name

A

–Meat, eggs, milk
–> Vegetarians are at risk for deficiency
* Vit B 12 absorbed in GI tract after complexing with intrinsic factor (IF)
* Vit B 12 transported in serum by transcobalamins I(cobalophilin), II, III.

115
Q

Intrinsic factor comes from

A

gastric parietal cells

116
Q

Vitamin B12 deficiencies

Result in what symptoms due to what

what types of anemia

A
  • Result in neurologic symptoms due to myelin sheath degeneration
  • Megaloblastic anemia due to impaired DNA synthesis, which results from folate
    deficiency
117
Q

hereditary VitB12 is known as

A

Imerslund Syndrome

118
Q

Older adults have higher incidence of Vit B12 deficiency due to

A

prob. due to poor
nutrition/ absorption

119
Q

Vitamin B12 measurements and Evaluation

A

Levels measured by immunoassay
* Once deficient confirmed, necessary to determine the cause of Vit B 12
deficiency
à often associated with defects in secretion of intrinsic factor
* Function test: traditional Schilling Test (not performed often

120
Q

Schillings test is for what and steps

A

Vitamin B12
1.) The Schilling test evaluates absorption of an oral dose of radioactive B-12 by measurement of urinary excretion of the radiolabeled vitamin.
2.) First–A large injection of B-12 is first administered to bind all B-12 binding sites.
3.) Then the oral radioactive dose of B-12 is administered.
If little radiolabeled vitamin is excreted (<10%), this generally indicates either malabsorption or lack of intrinsic factor.
4.) Wait 3-5 days for all radiolabeled B-12 to clear from body.
5.) Repeat test, but include an oral dose of IF (intrinsic factor) with the radioactive B-12.
6.) If the oral dose of IF causes increased absorption and excretion of the radiolabeled, then it is labeled a true pernicious anemia ( lack of IF).
7.) If it is not corrected it is an intestinal malabsorption problem, such as tropical sprue of D. latum infection

121
Q

Folic Acid is also known as

A

pteroylglutamic acid

122
Q

Folate is necessary for

what is necessary for folate metabolism

A

-Folate is necessary for normal DNA synthesis

  • Vit B 12 is necessary for the metabolism of folate, converting THF to 5’,10’methyl-THF form
    required for DNA synthesis
123
Q

Folic Acid - pteroylglutamic acid

Dietary sources

A

Primarily found in green leafy vegetables
Fruits
Organ meats
Boiling & use of large amounts of water result in vitamin destruction ( or washing away)

124
Q

Folic acid Dietary concerns

A

American diet may be inadequate in folate needs during adolescence, pregnancy and lactation
Rapid depletion may occur with increased need
Growth in adolescence, poor teen diet may result in deficiency

125
Q

Individuals planning families should wait to have adequate what

A

Individuals planning families should be sure to have adequate folate for one year prior to pregnancy (some say males, too).
Folate is part of prenatal vitamin supplement

126
Q

Folate Deficiency results in

Characterized chemically-

Hematological Characteristics-

A

results in megaloblastic anemia due to abnormal DNA synthesis
* Megaloblastic Anemia:
Characterized chemically by low erythrocyte folate and increased
homocysteine levels
Hematological Characteristics: macroovalocytes, hypersegmented
neutrophils, and megaloblastic marrow

127
Q

Classic Vitamin B12 assay

A

-Competitive Protein Binding Assays.
-The intrinsic factor was used as the binder and Co 57 as the radiolabel

128
Q

Vitamin B12

current assays

A

competitive binding immunoassay (Ab binder);
some form of FPIA or chemiluminescent IA

Boiling or chemical destruction of endogenous binders is required

129
Q

For Vitamin B12 use what samples and protect from

A

Fasting samples
* Must use serum: heparin binds Vit B 12
* Protect from light= Vit B 12 is photolytic

130
Q

Recent food intake increases what

A

Vitamin B12 serum

131
Q

Vitamin B12 storage

A

4 o C for
24 hours; -20 o C if > 24 hrs

132
Q

For Classic folate assay use

A

classic was CPB with β-
lactoglobulin as a binder and I125 as radiolabel

133
Q

Current method for Folate

A

-Current is immunoassay with Ab as binder
(FPIA or MEIA)
**Boiling or use of chemical inhibitors required to destroy
endogenous protein binders
or blocking may be used. (Endogenous binders
are albumin & FBP)

134
Q

Folate assays what samples are used

A

-Both Serum and RBC hemolysate are used as samples
* Fasting samples

135
Q

Folate Assay

Storage of serum specimens

A

4o C for 24 hours; -20 o C if > 24 hrs

136
Q

Reference values

A

Serum folate 1.9—14 ng/ml
RBC folate 200—1000 ng/ml

137
Q

Additional Assays: Vit B12 & Folate

A

-Serum & urinary methylmalonic acid
Will be increased in Vit B12 deficiency, but normal in folate deficiency
* Homocysteine
Will be increased in both Vit B12 and folate deficiency

138
Q

Carnitine (Bt)

types

A

L-carnitine & Acylcarnitines
—> ‘conditionally essential’ nutrient (AA)

139
Q

Carnitine (Bt)

Dietary resources

Average diets provide

Strict Vegetarian diets provide

A

Found in meat, poultry, fish and dairy products
Plants contain little, except peanut butter, asparagus and avocados

Average diets provide > half of human requirement; most is absorbed

“Strict vegetarian diets” provide ~10% of requiremen

140
Q

Carnitine metabolism

requires what for synthesis

where is the synthesis

A

New synthesis requires N-tri-methyllysine residues of proteins;
–> rate determined by the availability

Synthesis: Liver, Brain, Kidney.

Storage: Muscle

141
Q

Carnitine: Metabolism

Uptake from gut via

Excreted in

A

Carnitine Transport Protein

urine (free & esterified form)

142
Q

Carnitine Function

Facilitates entry of

A

Facilitates entry of long-chain FA into mitochondria for energy
production

143
Q

Carnitine: Primary Deficiency

results in

type of genetic disorder

Children symptoms

A

Rare
* Results in muscle weakness and fatigue
* Usually an “autosomal recessive disorder”
* Children: cardiomyopathy, hypoglycemia, elevated ammonia, muscle
weakness

144
Q

Administration of large doses of carnitine (temporarily) reverses what

A

primary carnitine deficiency

Administration of large doses of carnitine (temporarily) reverses
the disorder (which is a result of a mutation of the organic cation
transporter “OCNTN2”

145
Q

Other causes of primary carnitine deficiency

A

without cardiomyopathy are not clearly understood and “do
not always respond to carnitine supplements

146
Q

Carnitine Deficiency, Acquired

A
  • Inadequate intake
  • Increased urinary loss
  • Pregnancy and breast feeding: éé demand
  • Infants, children, and patients on long-term parenteral nutrition
    “most vulnerable groups”
147
Q

Secondary deficienciey results in

Patients on “hemodialysis” may lose

A

Muscle dysfunction

Patients on “hemodialysis” may lose carnitine in dialysis fluid (not yet
recommended supplementation)

148
Q

Carnitine: Other

Carnitine therapies are

A

are sometimes used with disorders of ammonia
metabolism, liver disorders

149
Q

Valproate is uses to

A

Valproate [used to treat epilepsy] is associated with liver toxicity: Carnitine
sometimes used in the management of liver injury caused by valproate.

Some studies of Alzheimiers dlsease

150
Q

L-Acetyl- Carnitine

A

somewhat beneficial in various trials of HIV-associated neuropathy
Some studies show benefits in treatment with carnitine for diabetes nepthropathy

151
Q

Vitamin Supplementation

A

-Vitamin supplementation may sometimes be warranted in nutritional
deficiencies
* No evidence exists to show intakes in excess of what is needed for
general health is useful
* Megadoses of vitamins have not shown to prevent common cold or
cancer or heart disease

Clinical Chemistry II - 4378 (28 decks)

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