LIPID AND LIPOPROTEIN METHODOLOGY Flashcards
Quiz (142 cards)
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
2
Q
Function of lipids:
A
help regulate hormones
transmit nerve impulses
cushion organs
store energy in the form of body fat
3
Q
Disorders of lipids
A
Arteriosclerosis
obesity
HTN
DM other abnormalities
4
Q
Indications for Lipid Profile include:
A
⁃ Screening for primary & secondary hyperlipidemias
⁃ Monitoring for risk of atherosclerosis
⁃ Monitoring treatment of hyperlipidemias/Dyslipidemia
5
Q
They are the plasma lipids of most interest in the diagnosis and management of lipoprotein disorders
A
CHOLESTEROL and TRIGLYCERIDE
6
Q
The term used for elevated lipids and cholesterol
A
HYPERLIPIDEMIAS
7
Q
Biological variations:
A
Age
Sex
Season
Food intake
Medical conditions
Acute illness
Life-style
8
Q
Fasting requirement before specimen collection
A
12 hours
9
Q
The concentration of LDL-C/HDL-C ______ after eating
A
declines
10
Q
They are are cleared within 6-9hrs and their presence after 12hrs fast is abnormal.
A
Chylomicrons
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
12
Q
Patient to be seated for _________ prior to sampling to prevent hemoconcentration.
A
5min
12
Q
Prolonged venous occlusion leads to increase in cholesterol conc by _________
A
10-15%
13
Q
_________ produces a slight decrease in conc of cholesterol and TG.
A
Mild exercise
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%
14
Q
The cyclical variation in cholesterol is not observed with __________.
A
anovulatory cycles
15
Q
A high fat diet increases serum _____
A
Triglyceride
16
Q
Ingestion of ___________ reduces cholesterol
A
monounsaturated fat
17
Q
___________ is reduced when sucrose intake is reduced.
A
Plasma triglyceride conc
18
Q
A high carbohydrate diet decreases the serum conc. of ____, ___, _______ and _____.
A
VLDL-C
TG
cholesterol
protein
19
Q
Large protein meals at lunch or in the evening also increase the serum cholesterol for atleast ________ after a meal.
A
1 hour
20
Q
In vegeterian individuals, conc. of ____ & _____ are reduced by 37 % and 12%.
A
LDL
VLDL-C
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 %
22
Q
_____ is lower in smokers than in non smokers
A
HDL cholesterol
23
Alcohol ingestion: - When moderate amount of alcohol is ingested for 1wk, the serum TG conc is increased by more than _________.
20mg/dL
24
Prolonged moderate ingestion may increase HDL-C conc ---> reduced plasma conc of __________.
cholesterol ester transfer protein(CETP)
25
What are the two specimen of choice?
Plasma
Serum
26
Plasma and serum - Either can be used when ___, ____ and _____ are measured
TC
TG
HDL-C
27
Plasma is preferred when lipoprotein are measured by:
1. Ultracentrifugation
2. Electrophoretic methods
28
________ can be used when it is necessary to store samples for weeks or months.
Serum
29
Measurements in the ________ seem to be little lower than _________
capillary samples
venous samples
30
What are the three anticoagulant used in Lipid determination?
Citrate
Heparin
EDTA
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It exert large osmotic effect resulting in falsely low plasma lipid and lipoprotein concentration.
Citrate
32
Anticoagulant used because of its high M.W can alter electrophoretic mobility of lipoproteins.
Heparin
33
Preferred anticoagulant even though TC and TG conc in this anticoagulant's plasma are 3% lower than in serum.
EDTA
34
Storage:
- ___________ can be satisfactorily analyzed in frozen samples.
- ____________can also be measured in frozen samples.
TC, TG, HDL-C
Apolipoproteins
35
Serum or plasma must be stored at ______ if stored for long time.
- 70°C
36
For short time storage (upto a month or two) the sample can be kept
at _____
-2 degrees
37
What are the two main cholecterol estimation methods?
Chemical methods
Enzymatic methods
38
Methods under chemical methods for cholesterol estimation
Abell Kendall Method
Bloors Methods
39
Former reference method for cholesterol estimation with 3 step.
Abell Kendall Method
40
What is the principle of AK method
3 step method
41
Abell Kendall Method is measured using what reaction?
L-B reaction / Liebermann-Burchardt reaction
42
What is the end product of L-B reaction?
Bluish green solution
43
Principle of Bloors method
2 step method
44
Reagent used in Bloors method
Alcohol ether mixture
45
Color developers of L-B reaction
Glacial acetic acid
Acetic anhyride
Concentrated Hydrogen sulfate
46
Method under enzymatic methods for cholesterol estimation
Cholesterol oxidase method
47
Routine lab-assay of choice
Cholesterol oxidase method
48
Three enzymes under Cholesterol oxidase method
Cholesterol esterase
Cholesterol oxidase
Peroxidase
49
Reaction used in Cholesterol oxidase method
Trinder's reaction
50
Wavelength of Cholesterol oxidase method
500nm
50
End product of Trinder's reaction
Quinoneimine dye (Red)
H2O
51
Linearity of Cholesterol oxidase method
600 - 700mg/dL (15.54 - 18.13mmol/L)
52
Advatanges of enzymatic method:
-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
53
Disadvatages of enzymatic methods:
- 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%
54
Increased cholesterol seen in what conditions?
- Biliary cirrhosis
- Hyperlipoproteinemia types II, III, V
- Nephrotic syndrome
- Uncontrolled DM
- Alcoholism
- Primary Hypothyroidism
55
Decreased cholesterol seen in what conditions?
- Severe hepatocellular disease (alcoholic liver disease)
- Malnutrition
- Severe burns
- Hyperthyroidism
- Malabsorption syndrome
56
Reference method used in cholesterol estimation
GC-MS METHOD / Gas Chromatography - Mass Spectrocopy
57
Specifically measures cholesterol and does not detect related sterols
Shows good agreement with the Definitive Method
GC-MS METHOD / Gas Chromatography - Mass Spectrocopy
58
Cholesterol Desirable level:
< 200mg/dL (< 5.2mmol/L)
59
Conversion factor from conventional to SI unit
0.026
60
Three methods under HDL estimation
Precipitation method
Polyanion precipitation
Magnetic method
61
Precipitating reagents such as divalent cations and polyanions are used to remove all lipoproteins except HDL
Precipitation method
62
Enzymatic method for total cholesterol
Precipitation method
63
Enzyme used in
enzymatic method for total cholesterol
Cholesterol oxidase
64
Lipoproteins are precipitated with polyanions like
heparin sulfate
dextran sulfate
phosphotungstate
65
POLYANION PRECIPITATION:
Reaction should be in the presence of divalent cations ___________
Mg, Ca and Mn
66
Most commonly for HDL and is reasonably specific.
POLYANION PRECIPITATION
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Interference from elevated TG levels causing incomplete sedimentation after centrifuging which results in over estimation of HDL-C
Demerit
68
Other name of HOMOGENOUS ASSAY
Direct HDL-C Assay
69
Use of Antibodies or Polymers or complexing agent
HOMOGENOUS ASSAY
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Example of Antibodies or Polymers or complexing agent
Cyclodextrin
71
Modification of cholesterol esterase and oxidase enzymes which makes them selective for ________
HDL-C
72
Use of blanking step that selectively consumes cholesterol from non-HDL species
HOMOGENOUS ASSAY
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Reference method for HDL-C estimation
Three-step Procedure
74
In Three-step procedure Heparin manganese precipitation to remove ___________
LDL
74
It is tedious and expensive
Three-step procedure
75
In Three-step Procedure ________ to remove VLDL
Ultracentrifugation
76
Permits fractionation or several or all classes of LPs in a single run
Density gradient methods
76
Uses sequential density adjustments of serum to fractionate major and minor classes of LP
Preparative Ultracentrifugation
77
Non-equilibrium or equilibrium techniques
Density gradient methods
78
Use antibody-coated plates specific for epitopes on apolipoproteins both in routine and research lab
IMMUNOCHEMICAL METHODS
79
Routine method of LDL-C Estimation
Fridewald equation/calculation method
80
LDL-Chol formula to get mmol/L
[TC - HDL-Chol] - Plasma TG/2.175
81
LDL-Chol formula to get mg/dL
[TC - HDL-Chol] - Plasma TG/5
82
VLDL (mg/dL) =
[TAG]/5
83
VLDL (mmol/L) =
[TAG]/2.175
84
Reference method for LDL-C estimation
Beta-Quantification
85
Selectively measures LDL after masking non-LDL cholesterol, OR
By selectively solubilizing LDL
Homogenous method
86
May be useful in evaluation of type Ill hyperlipoproteinemia
Expressed in mol/mol or mass/mass
VLDL-C/Plasma TG ratio
87
Most dense lipoprotein
HDL (1.090 g/mL)
88
Least dense lipoprotein
Chylomicrons (0.95 g/mL)
89
Lipids are extracted using chloroform and phospholipids and removed by zeolite absorption
Chemical method (TAG)
90
former reference method of Triglycerides
Van Handel and Zilversmith Method
91
class of lipids; used as energy in fasting state.
TAG
92
End color of TAG
pink end color
93
Steps in TAG where interfering substances are removed
During extraction (with chloroform)
Adsorption (Silicic acid chromatography)
94
The purpose of the silicic acid is
to remove phospholipids from the chloroform extract.
95
Demerit of TAG
Tedious, poorly characterized
GC-MS METHOD (Reference Method)
96
end product of fluorometric method
Fluorescence of yellow or yellow green
97
enzymatic method used in TAG
Glycerol kinase method
98
3 enzymes used in glycerol kinase method
Lipase
Glycerol kinase
Glycerophosphate oxidase
99
reaction used in glycerol kinase method
trinder's reaction
100
end color of trinder's reaction in glycerol kinase method
pink compound + H2O
101
linearity of glycerol kinase method
up to 700 mg/dL
102
Increased TAG is seen in what conditions?
Hyperlipoproteinemia type i, iib, iii, iv, v
Alcoholism
Nephrotic syndrome
Hypothyroidism
Pancreatitis
103
Decreased TAG is seen in what conditions?
MALABSORPTION SYNDROME
Malnutrition
Brain infarction
Hyperthyroidism
104
enumerate the Apolipoproteins
Apo B
Apo A-1
Lp (a)
105
an indicator of combined LDL and VLDL concentration
Apo B
106
major protein of HDL
Apo A-1
107
the variant of LDL, an independent indicator of CHD risk
Lp(a)
108
Commonly measured by Immunoassays of different types
Apolipoproteins
109
Reference ranges
a. Apo-A:
b. Apo-B:
c. Lp(a):
120-160 mg/dL
< 120 mg/dL
<30 mg/dL
110
most common method in Apolipoproteins;
advantages:
Easily adapted spectrophotometric analyzers allows the use of commercially available antisera and reference sera.
Immunoturbidimetry
111
can also be employed but requires a Nephelometer and so not commonly used
Immunonephelometric
112
Other immunochemical methods available include:
- Enzyme-linked Immunosorbent Assay (ELISA)
- Radial Immunodiffusion (RID)
- Radioimmunoassay (RIA)
113
Antibodies used may be either ______________
monoclonal or polyclonal
114
Hyperlipoproteinemias have been classified using the system, which is not commonly used today.
Fredrickson-Levy classification
115
Type I hyperlipoproteinemia is elevated in what lipid
Elevated chylomicrons
116
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein:
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
Elevated chylomicrons only
Type I Hyperlipoproteinemia
118
Type IIa hyperlipoproteinemia is increase in what?
Increased LDL
119
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein
1. Clear
2. Generally elevated
3. Normal
4. Apo-B 100 increased
120
Increased LDL
Type IIa Hyperlipoproteinemia
121
Type lIb hyperlipoproteinemia is increased in what substances?
: Increased LDL and VLDL
122
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein
1. Clear or slightly turbid
2. Elevated
3. Elevated
4. Apo B-100 increased
123
Increased VLDL and LDL
Type IIb hyperlipoproteinemia
124
Type III hyperlipoproteinemia
: Increased IDL
125
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein
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
Increased IDL
Type III hyperlipoproteinemia
127
Type IV hyperlipoproteinemia
: Increased VLDL
128
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein
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
Increased VLDL
Type IV hyperlipoproteinemia
130
Type V hyperlipoproteinemia
: Increased VLDL with increased chylomicrons
131
1) Serum appearance:
2) Total cholesterol:
3) Triglyceride:
4) Protein
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
: Increased VLDL with increased chylomicrons
Type V hyperlipoproteinemia
133
enumerate 4 hypolipoproteinemias
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
Total cholesterol level very low, triglyceride level nearly undetectable, LDL and Apo B-100 absent
Abetalipoproteinemia:
135
Unable to synthesize apo B-100 and apo B-48, low total cholesterol level and normal to low triglyceride level
Hypobetalipoproteinemia:
136
Severely elevated triglyceride level and low HDL level
Hypoalphalipoproteinemia:
137
HDL absent, apo A-I and apo A-II very low levels, LDL low, total cholesterol level low, triglyceride level normal to slightly increased
Tangier disease:
