LIPID AND LIPOPROTEIN METHODOLOGY Flashcards

Quiz

1
Q

they are fatty, waxy, or oily compounds that are essential to many body functions and serve as the building blocks for all living cells.

A

Lipids

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2
Q

Function of lipids:

A

help regulate hormones
transmit nerve impulses
cushion organs
store energy in the form of body fat

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3
Q

Disorders of lipids

A

Arteriosclerosis
obesity
HTN
DM other abnormalities

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4
Q

Indications for Lipid Profile include:

A

⁃ Screening for primary & secondary hyperlipidemias
⁃ Monitoring for risk of atherosclerosis
⁃ Monitoring treatment of hyperlipidemias/Dyslipidemia

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5
Q

They are the plasma lipids of most interest in the diagnosis and management of lipoprotein disorders

A

CHOLESTEROL and TRIGLYCERIDE

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6
Q

The term used for elevated lipids and cholesterol

A

HYPERLIPIDEMIAS

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7
Q

Biological variations:

A

Age
Sex
Season
Food intake
Medical conditions
Acute illness
Life-style

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8
Q

Fasting requirement before specimen collection

A

12 hours

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9
Q

The concentration of LDL-C/HDL-C ______ after eating

A

declines

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10
Q

They are are cleared within 6-9hrs and their presence after 12hrs fast is abnormal.

A

Chylomicrons

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11
Q

______ causes the decreases of as much 10% in concentration of ________________

A

Posture
TC, LDL-C, HDL-C and apo-A-1 and B

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12
Q

Patient to be seated for _________ prior to sampling to prevent hemoconcentration.

A

5min

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12
Q

Prolonged venous occlusion leads to increase in cholesterol conc by _________

A

10-15%

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13
Q

_________ produces a slight decrease in conc of cholesterol and TG.

A

Mild exercise

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13
Q

Those who walk for about 4 hours each week have an average cholesterol____ lower and HDL-C ____ higher than inactive persons

A

5%
3.4%

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14
Q

The cyclical variation in cholesterol is not observed with __________.

A

anovulatory cycles

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15
Q

A high fat diet increases serum _____

A

Triglyceride

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16
Q

Ingestion of ___________ reduces cholesterol

A

monounsaturated fat

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17
Q

___________ is reduced when sucrose intake is reduced.

A

Plasma triglyceride conc

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18
Q

A high carbohydrate diet decreases the serum conc. of ____, ___, _______ and _____.

A

VLDL-C
TG
cholesterol
protein

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19
Q

Large protein meals at lunch or in the evening also increase the serum cholesterol for atleast ________ after a meal.

A

1 hour

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20
Q

In vegeterian individuals, conc. of ____ & _____ are reduced by 37 % and 12%.

A

LDL
VLDL-C

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21
Q

The plasma cholesterol, triglyceride and LDL cholesterol conc. are higher by about ___, ___ and _____ respectively in smokers than in non smokers.

A

3 %
9.1 %
1.7 %

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22
Q

_____ is lower in smokers than in non smokers

A

HDL cholesterol

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23
Q

Alcohol ingestion: - When moderate amount of alcohol is ingested for 1wk, the serum TG conc is increased by more than _________.

A

20mg/dL

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24
Q

Prolonged moderate ingestion may increase HDL-C conc —> reduced plasma conc of __________.

A

cholesterol ester transfer protein(CETP)

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25
Q

What are the two specimen of choice?

A

Plasma
Serum

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26
Q

Plasma and serum - Either can be used when ___, ____ and _____ are measured

A

TC
TG
HDL-C

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27
Q

Plasma is preferred when lipoprotein are measured by:

A
  1. Ultracentrifugation
  2. Electrophoretic methods
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28
Q

________ can be used when it is necessary to store samples for weeks or months.

A

Serum

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29
Q

Measurements in the ________ seem to be little lower than _________

A

capillary samples
venous samples

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30
Q

What are the three anticoagulant used in Lipid determination?

A

Citrate
Heparin
EDTA

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31
Q

It exert large osmotic effect resulting in falsely low plasma lipid and lipoprotein concentration.

A

Citrate

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32
Q

Anticoagulant used because of its high M.W can alter electrophoretic mobility of lipoproteins.

A

Heparin

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33
Q

Preferred anticoagulant even though TC and TG conc in this anticoagulant’s plasma are 3% lower than in serum.

A

EDTA

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34
Q

Storage:
- ___________ can be satisfactorily analyzed in frozen samples.
- ____________can also be measured in frozen samples.

A

TC, TG, HDL-C
Apolipoproteins

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35
Q

Serum or plasma must be stored at ______ if stored for long time.

A
  • 70°C
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36
Q

For short time storage (upto a month or two) the sample can be kept
at _____

A

-2 degrees

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37
Q

What are the two main cholecterol estimation methods?

A

Chemical methods
Enzymatic methods

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38
Q

Methods under chemical methods for cholesterol estimation

A

Abell Kendall Method
Bloors Methods

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39
Q

Former reference method for cholesterol estimation with 3 step.

A

Abell Kendall Method

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40
Q

What is the principle of AK method

A

3 step method

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41
Q

Abell Kendall Method is measured using what reaction?

A

L-B reaction / Liebermann-Burchardt reaction

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42
Q

What is the end product of L-B reaction?

A

Bluish green solution

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43
Q

Principle of Bloors method

A

2 step method

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44
Q

Reagent used in Bloors method

A

Alcohol ether mixture

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45
Q

Color developers of L-B reaction

A

Glacial acetic acid
Acetic anhyride
Concentrated Hydrogen sulfate

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46
Q

Method under enzymatic methods for cholesterol estimation

A

Cholesterol oxidase method

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47
Q

Routine lab-assay of choice

A

Cholesterol oxidase method

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48
Q

Three enzymes under Cholesterol oxidase method

A

Cholesterol esterase
Cholesterol oxidase
Peroxidase

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49
Q

Reaction used in Cholesterol oxidase method

A

Trinder’s reaction

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50
Q

Wavelength of Cholesterol oxidase method

A

500nm

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50
Q

End product of Trinder’s reaction

A

Quinoneimine dye (Red)
H2O

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51
Q

Linearity of Cholesterol oxidase method

A

600 - 700mg/dL (15.54 - 18.13mmol/L)

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52
Q

Advatanges of enzymatic method:

A

-Precise and accurate
-Lesser interferences - bilirubin, ascorbic acid, Hb
- Smaller sample quantity
- Rapid; does not require preliminary extraction step
- Can be used to measure unesterified cholesterol by omitting de-esterification step
- Mild reagents; better suited for automated analyzers

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53
Q

Disadvatages of enzymatic methods:

A
  • They are not absolutely specific for cholesterol.
    -Cholesterol oxidase reacts with other sterols e.g plant sterol
  • Ascorbic acid and- Bilirubin interfere by consuming H202
  • Bilirubin interference can produce falsely high or low values
  • Significant only at conc >5mg/dL decreasing Cholesterol values by 5 - 15%
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54
Q

Increased cholesterol seen in what conditions?

A
  • Biliary cirrhosis
  • Hyperlipoproteinemia types II, III, V
  • Nephrotic syndrome
  • Uncontrolled DM
  • Alcoholism
  • Primary Hypothyroidism
55
Q

Decreased cholesterol seen in what conditions?

A
  • Severe hepatocellular disease (alcoholic liver disease)
  • Malnutrition
  • Severe burns
  • Hyperthyroidism
  • Malabsorption syndrome
56
Q

Reference method used in cholesterol estimation

A

GC-MS METHOD / Gas Chromatography - Mass Spectrocopy

57
Q

Specifically measures cholesterol and does not detect related sterols

Shows good agreement with the Definitive Method

A

GC-MS METHOD / Gas Chromatography - Mass Spectrocopy

58
Q

Cholesterol Desirable level:

A

< 200mg/dL (< 5.2mmol/L)

59
Q

Conversion factor from conventional to SI unit

A

0.026

60
Q

Three methods under HDL estimation

A

Precipitation method
Polyanion precipitation
Magnetic method

61
Q

Precipitating reagents such as divalent cations and polyanions are used to remove all lipoproteins except HDL

A

Precipitation method

62
Q

Enzymatic method for total cholesterol

A

Precipitation method

63
Q

Enzyme used in
enzymatic method for total cholesterol

A

Cholesterol oxidase

64
Q

Lipoproteins are precipitated with polyanions like

A

heparin sulfate
dextran sulfate
phosphotungstate

65
Q

POLYANION PRECIPITATION:
Reaction should be in the presence of divalent cations ___________

A

Mg, Ca and Mn

66
Q

Most commonly for HDL and is reasonably specific.

A

POLYANION PRECIPITATION

67
Q

Interference from elevated TG levels causing incomplete sedimentation after centrifuging which results in over estimation of HDL-C

A

Demerit

68
Q

Other name of HOMOGENOUS ASSAY

A

Direct HDL-C Assay

69
Q

Use of Antibodies or Polymers or complexing agent

A

HOMOGENOUS ASSAY

70
Q

Example of Antibodies or Polymers or complexing agent

A

Cyclodextrin

71
Q

Modification of cholesterol esterase and oxidase enzymes which makes them selective for ________

A

HDL-C

72
Q

Use of blanking step that selectively consumes cholesterol from non-HDL species

A

HOMOGENOUS ASSAY

73
Q

Reference method for HDL-C estimation

A

Three-step Procedure

74
Q

In Three-step procedure Heparin manganese precipitation to remove ___________

A

LDL

74
Q

It is tedious and expensive

A

Three-step procedure

75
Q

In Three-step Procedure ________ to remove VLDL

A

Ultracentrifugation

76
Q

Permits fractionation or several or all classes of LPs in a single run

A

Density gradient methods

76
Q

Uses sequential density adjustments of serum to fractionate major and minor classes of LP

A

Preparative Ultracentrifugation

77
Q

Non-equilibrium or equilibrium techniques

A

Density gradient methods

78
Q

Use antibody-coated plates specific for epitopes on apolipoproteins both in routine and research lab

A

IMMUNOCHEMICAL METHODS

79
Q

Routine method of LDL-C Estimation

A

Fridewald equation/calculation method

80
Q

LDL-Chol formula to get mmol/L

A

[TC - HDL-Chol] - Plasma TG/2.175

81
Q

LDL-Chol formula to get mg/dL

A

[TC - HDL-Chol] - Plasma TG/5

82
Q

VLDL (mg/dL) =

A

[TAG]/5

83
Q

VLDL (mmol/L) =

A

[TAG]/2.175

84
Q

Reference method for LDL-C estimation

A

Beta-Quantification

85
Q

Selectively measures LDL after masking non-LDL cholesterol, OR
By selectively solubilizing LDL

A

Homogenous method

86
Q

May be useful in evaluation of type Ill hyperlipoproteinemia
Expressed in mol/mol or mass/mass

A

VLDL-C/Plasma TG ratio

87
Q

Most dense lipoprotein

A

HDL (1.090 g/mL)

88
Q

Least dense lipoprotein

A

Chylomicrons (0.95 g/mL)

89
Q

Lipids are extracted using chloroform and phospholipids and removed by zeolite absorption

A

Chemical method (TAG)

90
Q

former reference method of Triglycerides

A

Van Handel and Zilversmith Method

91
Q

class of lipids; used as energy in fasting state.

A

TAG

92
Q

End color of TAG

A

pink end color

93
Q

Steps in TAG where interfering substances are removed

A

During extraction (with chloroform)
Adsorption (Silicic acid chromatography)

94
Q

The purpose of the silicic acid is

A

to remove phospholipids from the chloroform extract.

95
Q

Demerit of TAG

A

Tedious, poorly characterized

GC-MS METHOD (Reference Method)

96
Q

end product of fluorometric method

A

Fluorescence of yellow or yellow green

97
Q

enzymatic method used in TAG

A

Glycerol kinase method

98
Q

3 enzymes used in glycerol kinase method

A

Lipase
Glycerol kinase
Glycerophosphate oxidase

99
Q

reaction used in glycerol kinase method

A

trinder’s reaction

100
Q

end color of trinder’s reaction in glycerol kinase method

A

pink compound + H2O

101
Q

linearity of glycerol kinase method

A

up to 700 mg/dL

102
Q

Increased TAG is seen in what conditions?

A

Hyperlipoproteinemia type i, iib, iii, iv, v
Alcoholism
Nephrotic syndrome
Hypothyroidism
Pancreatitis

103
Q

Decreased TAG is seen in what conditions?

A

MALABSORPTION SYNDROME
Malnutrition
Brain infarction
Hyperthyroidism

104
Q

enumerate the Apolipoproteins

A

Apo B
Apo A-1
Lp (a)

105
Q

an indicator of combined LDL and VLDL concentration

A

Apo B

106
Q

major protein of HDL

A

Apo A-1

107
Q

the variant of LDL, an independent indicator of CHD risk

A

Lp(a)

108
Q

Commonly measured by Immunoassays of different types

A

Apolipoproteins

109
Q

Reference ranges
a. Apo-A:
b. Apo-B:
c. Lp(a):

A

120-160 mg/dL
< 120 mg/dL
<30 mg/dL

110
Q

most common method in Apolipoproteins;
advantages:
Easily adapted spectrophotometric analyzers allows the use of commercially available antisera and reference sera.

A

Immunoturbidimetry

111
Q

can also be employed but requires a Nephelometer and so not commonly used

A

Immunonephelometric

112
Q

Other immunochemical methods available include:

A
  • Enzyme-linked Immunosorbent Assay (ELISA)
  • Radial Immunodiffusion (RID)
  • Radioimmunoassay (RIA)
113
Q

Antibodies used may be either ______________

A

monoclonal or polyclonal

114
Q

Hyperlipoproteinemias have been classified using the system, which is not commonly used today.

A

Fredrickson-Levy classification

115
Q

Type I hyperlipoproteinemia is elevated in what lipid

A

Elevated chylomicrons

116
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein:

A
  1. Creamy layer of chylomicrons over clear serum
  2. Normal to moderately elevated
  3. Extremely elevated
  4. Apo B-48 increased, Apo A-IV increased
117
Q

Elevated chylomicrons only

A

Type I Hyperlipoproteinemia

118
Q

Type IIa hyperlipoproteinemia is increase in what?

A

Increased LDL

119
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein

A
  1. Clear
  2. Generally elevated
  3. Normal
  4. Apo-B 100 increased
120
Q

Increased LDL

A

Type IIa Hyperlipoproteinemia

121
Q

Type lIb hyperlipoproteinemia is increased in what substances?

A

: Increased LDL and VLDL

122
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein

A
  1. Clear or slightly turbid
  2. Elevated
  3. Elevated
  4. Apo B-100 increased
123
Q

Increased VLDL and LDL

A

Type IIb hyperlipoproteinemia

124
Q

Type III hyperlipoproteinemia

A

: Increased IDL

125
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein

A
  1. Creamy layer sometimes present over a turbid layer
  2. Elevated
  3. Elevated
  4. Apo E-II increased, Apo E-III decreased, and Apo E-IV decreased
126
Q

Increased IDL

A

Type III hyperlipoproteinemia

127
Q

Type IV hyperlipoproteinemia

A

: Increased VLDL

128
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein

A
  1. Turbid
  2. Normal to slightly elevated
  3. Moderately to severely elevated
  4. Apo C-II either increased or decreased, and Apo B-100 increased
129
Q

Increased VLDL

A

Type IV hyperlipoproteinemia

130
Q

Type V hyperlipoproteinemia

A

: Increased VLDL with increased chylomicrons

131
Q

1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein

A
  1. Turbid with creamy layer
  2. Slightly to moderately elevated
  3. Severely elevated
  4. Apo C-II increased or decreased, Apo B-48 increased, and Apo B-100
    increased
132
Q

: Increased VLDL with increased chylomicrons

A

Type V hyperlipoproteinemia

133
Q

enumerate 4 hypolipoproteinemias

A

Abetalipoproteinemia:
Hypobetalipoproteinemia:
Hypoalphalipoproteinemia:
NIEMANN PICK DISEASE
TANGIER’S DISEASE
LPL DEFICIENCY
GAUCHER DISEASE
TAY SACHS
FABRY DISEASE
KRABBE’S DISEASE
HURLER SYNDROME
HUNTER SYNDROME

134
Q

Total cholesterol level very low, triglyceride level nearly undetectable, LDL and Apo B-100 absent

A

Abetalipoproteinemia:

135
Q

Unable to synthesize apo B-100 and apo B-48, low total cholesterol level and normal to low triglyceride level

A

Hypobetalipoproteinemia:

136
Q

Severely elevated triglyceride level and low HDL level

A

Hypoalphalipoproteinemia:

137
Q

HDL absent, apo A-I and apo A-II very low levels, LDL low, total cholesterol level low, triglyceride level normal to slightly increased

A

Tangier disease: