LEC LIPIDS PART 2 - LIPID DETERMINATION Flashcards
Disorders of lipids
Arteriosclerosis, obesity, hypertension, DIABETES MELLITUS and other abnormalities
Good prognosis if lipid
Early detection of deranged blood lipid profile
age for screening for lipid
20 years old, if the test is normal repeat again after 5 yrs
if not, depends on the physician
- Indications for Lipid Profile include:
- ⁃ Screening for primary & secondary
hyperlipidemias - ⁃ Monitoring for risk of atherosclerosis
3.⁃ Monitoring treatment of
hyperlipidemias/Dyslipidemia
preanalytical considerations
biological variations such as
- Age: cholesterol levels increase with age.
- Sex: women have lower level than men except in childhood & after early 50’s.
- Season: cholesterol levels are slightly higher in cold periods.
- Food intake: daily intake of fat increases cholesterol levels.
- Medical conditions: thyroid, liver, and kidney diseases
- Acute illness
- Life-style: higher in sedentary and poor diet habits
explain the cholesterol level in terms of age
it increases with age
describe the gender relation of cholesterol
women have lower level than men except in childhood and after early 50`s
high in menopausal stage
can season affect cholesterol?
higher in cold cholesterol
why do menopausal women has high chole or high lipid profile?
because estrogen came from chole, if the cholesterol are can’t be converted into estrogen any longer, it will be deposited and stuck in the blood stream elevating lipids in the body
daily intake of fat increases cholesterol levels
true or false
true
in hyperthyroidism, chole is low because?
because of fast metabolism
if we have liver disease, do we have high or low chole?
low, 85% of chole is produced by the liver. If the liver is defected, there will be no organ that will produce it
describe the lipid profile of chronic alcoholic patients
low
describe the lipid profile of moderate alcoholic patients
high
components that clears the chylomicron
lipoprotein lipase that are activated by apo C2
Patient should fast for ___hours before sampling
12
Chylomicrons are cleared within__hrs and their presence
after 12hrs fast is abnormal.
6-9
Posture: Decreases of as much_________ of TC, LDL-C, HDL-C and apo-A-1 and B
10 %
correct position of getting sample
supine and lying position
Patient to be seated for __ prior to sampling to prevent hemoconcentration.
5min
Prolonged venous occlusion leads to increase in cholesterol conc by _______.
venous occlusion means tourniquet
10-15%
Exercise: Mild exercise produces a slight decrease in
conc of _______________.
chole and triglycerides
Those who walk for about 4 hours each week have an average cholesterol ___ lower and HDL-C ___ higher than inactive persons
5%; 3.4%
lipids that has higher concentration in the midcycle of menstruation
plasma Cholesterol and Triglycerides
A high fat diet increases serum __
triglyceride
-Ingestion of monounsaturated fat reduces __.
cholesterol
__ conc is reduced when sucrose intake is reduced.
Plasma triglyceride
A high carbohydrate diet decreases the serum conc. of___
VLDL-C, TG,
cholesterol and protein.
Large protein meals at lunch or in the evening also ___ the serum
cholesterol for atleast 1 hour after a meal.
increase
In vegeterian individuals, conc. of LDL & VLDL-C are reduced by ___ and ____
LDL 37%
VLDL 12%
Smoking:
The plasma cholesterol, triglyceride and LDL cholesterol conc. are higher by about ___respectively in smokers
than in non smokers
3 %, 9.1 % and 1.7 %
cholesterol, 3 %,
triglyceride 9.1 %
LDL cholesterol 1.7 %
__ cholesterol is lower in smokers than in non smokers
HDL
When MODERATE amount of alcohol is ingested
for 1wk, the serum TG conc is increased by more than _________.
20 mg/dl
Prolonged moderate ingestion of alcohol may increase HDL-C conc
it will reduced the plasma concentration of
cholesterol ester transfer protein(CETP).
what sample can we use for lipid profile?
either plasma or serum
___ is preferred when lipoprotein are measured by ultracentrifugation and electrophoretic methods
Plasma
if plasma is used for lipid profile, what anticoagulant is the best choice?
edta
2 methods to detect lipoprotein using plasma
ultracentrifugation and electrophoretic methods
reference method for lipoprotein determination
ultracentrifugation
the only lipoprotein that is only in the origin during the electrophoresis
chylomicron
which sample tend to have lower concentration of lipids
venous or capillary?
and why?
capillary - same with glucose, because of water
an anticoagulant that will exert large osmotic effect
citrate
Citrate: exert large osmotic effect resulting in falsely __ plasma lipid and
lipoprotein concentration.
low
an anticoagulant that can alter electrophoretic mobility of
lipoproteins.
heparin
heparin can alter electrophoretic mobility of
lipoproteins because of its __
high molecular weight
electrophoresis is separation of components depending on the
sizes
EDTA plasma
are ___% lower than in serum.
3%
in terms of storing
TC, TG, HDL-C can be satisfactorily analyzed in ___ samples.
frozen
aside from total chole, hdl, and tg
-__ can also be measured in frozen samples.
Apolipoproteins
Cholesterol Estimation has 2 methods, what are they
chemical and enzymatic method
if we have a given serum and we need to convert it to plasma, what formula we should use?
serum x 3%
if we have plasma and we need to find the serum, what’s the formula
X 1.03
we store sample or plasma in what temperature for a long time
- 70*
we store sample or plasma in what temperature for a short time (1-2 months)
-2 *
what is the former reference method for chemical estimation
abell kendall method
3 steps of abell kendall method
- Cholesterol is HYDROLYZED with alcoholic KOH
- Unesterified cholesterol is EXTRACTED with petroleum jelly/Hexane
- Measured using the L-B Reaction (COLORIMETRY)
RESULT OF HYDROLYZING CHOLESTEROL
cholesterol ester AND FATTY ACIDS
removing cholesterol from fatty acids is
free cholesterols
how Liebermann-burchardt reaction works?
the unsterified extracted will combined with sulfuric acid and acetic anhydride to form a bluish green solution
unsterified Cholesterol + Sulfuric acid + Acetic anhydride bluish green solution
end product of liebermann-burchardt’s reaction
bluish green solution called Cholestadienyl monosulfonic acid
purpose of acetic anhydride and sulfuric acid
color developers
another chemical method for cholesterol estimation that only uses 2 steps
Bloors Method
Bloors Method: - Principle: 2 step
- Cholesterol is extracted using an alcohol ether mixture
- Measured using the L-B Reaction
in bloor’s method, the cholesterol is extracted using
alcohol ether mixture
in abell kendall method - the cholesterol is extracted using
petroleum jelly and hexane
in abell kendall method - the cholesterol is hydrolyzed using
alcoholic potassium hydroxide KOH
what is the principle of abell kendall method
3 step method - hydrolysis, extraction, colorimetry
what is the principle of enzymatic method
cholesterol oxidase method
Routine Lab - Assay of Choice for cholesterol
Cholesterol Oxidase Method
Cholesterol Oxidase Method is only specific for __
cholesterol esters
cholesterol esters are those cholesterols with ___
fatty acids
the cholesterol ester are hydrolyze by what enzyme to form free chole and fatty acids
cholesterol esterase
free cholesterol will be oxidized by what enzyme
cholesterol oxidase
free cholesterol will be oxidized by cholesterol oxidase to form
4 cholestene - 3 - one + h202
what is the goal of oxidizing free cholesterol in cholesterol oxidase method
to find the H202 which will be used in trinder’s reaction
in trinders reaction we uses what enzyme
PEROXIDASE
what specific peroxidase is used for trinder’s reaction
horse raddish peroxidase
what dye is used to form quinoneimine dye in trinder’s reaction
4-aminophenazone
a sequential reaction in trinder’s reaction
low chole shows
high chole show
low chole shows pink
high chole show red
in trinder’s reaction or oxidase method, how many enzymes are used
3 - esterase , oxidase, peroxidase
cholesterol oxidation or trinder’s method is read at what wavelength?
520 nm
cholesterol oxidase method has a linearity up to
600 - 700mg/dL (15.54 - 18.13mmol/L)
normal value of cholesterol
ADVANTAGE 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
DISADVANTAGE of enzymatic reaction
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%
INCREASED CHOLESTEROL are found in
- Biliary cirrhosis
- Hyperlipoproteinemia types
II, III, V - Nephrotic syndrome
- Uncontrolled DM
- Alcoholism
- Primary Hypothyroidism
DECREASED CHOLESTEROL
- Severe hepatocellular
disease (alcoholic liver
disease) - Malnutrition
- Severe burns
- Hyperthyroidism
- Malabsorption syndrome
limit of interferences of bilirubin for chole
not greater than 200 mg/dl
limit of interferences of hemoglobin for chole
not greater than 20 mg/dl
more than 5 mg/dl in bilirubin will interfere to chole increasing the value of _- %
5-15%
the reference method for cholesterol
gas chromatography/mass spectrometry
gc ms
Cholesterol Desirable level:
: < 200mg/dL (< 5.2mmol/L);
in a modified abell kendall method, they use hexane, chloroform, and silisic acid
what is the purpose of chloroform in the process?
remove phospholipid
the color of the end product of the modified abell kendall method
pink
what kind of lipid is affected in a fasting specimen?
LDL and Triglyceride
in a modified abell kendall method, they use hexane, chloroform, and silisic acid
what is the purpose of silisic acid?
adsorption of phospholipid via chromatography
a post prandial lipemia
chylomicron
in non fasting sample, what type of triglyceride carrying lipoprotein is found
chylomicron
we use plasma - the preferred sample for measuring lipoprotein.
In ultracentrifugation, what substance do we use __ to separate lipoproteins based on density
potassium bromide
what apoprotein that can inhibit the function of apo c2?
apo protein c3
if we go under fasting, what type of triglyceride carrying lipoprotein can we observed on greatest amount?
vldl
what is the specific
1.063`
polyanions
heparin sulfate, dextran sulfate and phosphotungstate
divalent cations
Mg, Ca and Mn
Most commonly for HDL and is reasonably specific
POLYANION PRECIPITATION:
the cdc reference method
abell kendall
what’s in it inside the cholesterol making them possible to be measured using colorimetric assay/chemical method
the presence of double bonds and hydroxyl groups of the esterols
what is the end product of the salkowski method
cholestadienyl disulfonic acid - red solution
Precipitating reagents such as ___ and ____ are used to remove all lipoproteins except
HDL
divalent cations and polyanions
how can ascorbic acid affect the result of cholesterol determination
falsely decrease
how can hemoglobin and bilirubin affects the result of cholesterol determination
falsely increase
how can high level of triglyceride affect hdl determination
elevated triglyceride results to incomplete sedimentation which is as well will cause the hdl result elevated
Similar to the HDL-C precipitation method but uses a
precipitant that is complexed to magnetic particle
MAGNETIC METHOD
This sediments and does not require centrifugation
MAGNETIC METHOD
Has been adapted for use in automated clinical chemistry
analyzers
MAGNETIC METHOD
It allows the supernatant to be analyzed without the
need to remove it from the sedimented complex
MAGNETIC METHOD
homogenous assay or direct hdl c assay is a type of what method
enzymatic method
HOMOGENOUS ASSAY (Direct HDL-C Assay):
Enzymatic method: First reagent - “___” non-HDLs
blocks
blocker for homogenous assay
Use of Antibodies or Polymers or complexing agent
e.g Cyclodextrin
HOMOGENOUS ASSAY (Direct HDL-C Assay) steps
Enzymatic method: First reagent - “blocks” non-HDLs
Use of Antibodies or Polymers or complexing agent
e.gCyclodextrin
Modification of cholesterol esterase and oxidase enzymes which makes them selective for HDL-C
Use of blanking step that selectively consumes cholesterol from non-HDL species
Reference method for HDL-C
estimation is
Three-step Procedure
comment about three step procedure
tedious and expensive
2 types of ULTRACENTRIFUGATION
Preparative Ultracentrifugation
Density gradient method
a type of centrifugation that Uses sequential density adjustments of serum to FRACTIONATE MAJOR and MINOR classes of LP
Preparative Ultracentrifugation
(non-equilibrium or equilibrium
techniques) permits fractionation or several or ALL classes of LPs in a
single run
Density gradient methods -
Use antibody-coated plates specific for epitopes on apolipoproteins
both in routine and research lab
IMMUNOCHEMICAL METHODS
INDIRECT METHODS of LDL c estimation
friedewald equation
what is the equation of friedewald
LDL - TC - HDL - TG/2.175 in mmol/L
LDL - TC - HDL - TG/5 in mg/dl
Tedious -reserved for samples where Friedewald
equation is inappropriate
Beta-Quantification
(Reference method) for ldl estimation
Beta-Quantification
2 steps of Beta-Quantification
- Ultracentrifugation to remove VLDL leaving behind LDL and HDL as well as IDL and Lp(a)
- Chemical Precipitation of HDL-C
in the ultracentrifugation, we are removing ___ to keep __ and ___ as well
as IDL and Lp(a)
vldl; ldl and hdl
Limitations of ldl c estimation in indirect or friedwald method
not appropriate in:
- Samples with TG > 400mg/dL
- Patients with suspected Dysbetalipoproteinaemia
Other limitations of ldl estimation ; indirect or friedewald equation
- Does not account for cholesterol associated with IDL and Lp(a)
- Underestimate LDL-C in chronic alcoholics
- Unsuitable for monitoring
- Mis-classifies 15 - 40 % of patients when TG levels are between 200 to 400 mg/dL
Selectively measures LDL after masking non
LDL cholesterol, OR By selectively solubilizing LDL
Homogenous method
Advantages of homogenous method
Does not involve measurement of TGs thus
non-fasting samples can be used
Comparable to calculated LDL results from
beta-quantitation on normal lipemic
specimens
May be useful in evaluation of type Ill
hyperlipoproteinemia
VLDL-C/Plasma TG ratio
VLDL-C/Plasma TG ratio is expressed in
mol/mol or mass/mass
> 0.689 in VLDL-C/Plasma TG ratio means
hyperlipoproteinemi
VLDL-C/Plasma TG ratio ref range
0.689- 0.091
VLDL-C/Plasma TG ratio
Ranges ___ in samples without beta VLDL
0.230-0.575
give the arrangement of the lipoprotein from top to bottom arranged using electrophoresis
origin - chylomicron
ldl - beta
vldl - pre beta
hdl - alpha
the most anodic lipoprotein in electrophoresis
hdl - alpha lipoprotein
arrange the density of the lipoproteins out from ultracentrifugation
chylomicrons - 0.95 g/ml
vldl - 1.006 g/ml
IDL - 1.019 g/ml
LDL - 1.063 g/ml
HDL - 1.090 g/ml
fatty acids + albumin
in electrophoresis, we used the most sensitive type of gel or medium
agarose gel or polyacrylamide
stain used in electrophoresis for lipoprotein
Oil red O
Sudan
Fat Red 7b
former
Reference Method) for triglyceride
Van Handel and Zilversmith Method
in Triglycerides/TAG:
chemical method
- Lipids are extracted using chloroform and
phospholipids and removed by __ absorption
zeolite
Principle or steps of van handel zilversmith method
1.
TAG – > alcoholic KOH Glycerol + Fatty
acids
2. Glycerol + periodic acid –> Formaldehyde
3. Formaldehyde + Chromotropic acid ——> Blue
solution
in Van Handel and Zilversmith Method
what is added in the formaldehyde?
Chromotropic acid
in Van Handel and Zilversmith Method
what is the end product color
blue solution
a modification of in Van Handel and Zilversmith Method that will not use colorimetry but instead fluorimetry
hantzsch condensation method
hantzsch condensation method
steps or principle
1.TAG – > alcoholic KOH –>Glycerol + Fatty
acids
2. Glycerol + periodic acid –> Formaldehyde
3. Formaldehyde + acetone + ammonia ——> yellow
solution
in hantzsch condensation method
what is added in formaldehyde
acetone and ammonia
in hantzsch condensation method
what is the end color
yellow
principle of enzymatic method of triglyceride is based on
glycerol kinase method
chromogen used in trinder’s reaction in tryglyceridee determination
4 amino antipyrine
in chemical method - glycerol kinase method
the end color is
pink
Glycerol Kinase Method Read absorbance at ___ wavelength
500nm
Glycerol Kinase Method Read absorbance at 550 nm wavelength and linear up to
___
700mg/dL
INCREASED TAG are seen in
- Hyperlipoproteinemia type i,
iib, iii, iv, v - Alcoholism
- Nephrotic syndrome
- Hypothyroidism
- Pancreatitis
DECREASED TAG are seen in
- MALABSORPTION
SYNDROME - Malnutrition
- Brain infarction
- Hyperthyroidism
an indicator of combined LDL and VLDL
concentration
Apo B:
major protein of HDL
Apo A-1:
the variant of LDL, an independent indicator
of CHD risk
Lp(a):
reference method or rnage of Apo A
120 - 160mg/dl
reference method or rnage of Apo B
< 120 mg/dl
reference method or range of Lp A
< 30 mg/dl
Hyperlipoproteinemias have been classified using the
system, which is not commonly used today.
Fredrickson-Levy classification
Mostcommonmethod for apoprotein
IMMUNOTURBIDIMETRY
easily adapted spectrophotometric analyzers allows the use of commercially available antisera and reference sera
IMMUNOTURBIDIMETRY
apoprotein that has indirect relation to coronary disease
apo A
other test we can conduct for apolipoprotein
ELISA , radial immunodiffusion, keme keme
Type I hyperlipoproteinemia: has an Elevated ___
chylomicrons
Type IIa hyperlipoproteinemia: has an increased
Increased LDL
Type lIb hyperlipoproteinemia: Increased ___
LDL and VLDL
Type III hyperlipoproteinemia: Increased ___
IDL
Type IV hyperlipoproteinemia: Increased ___
VLDL
Type V hyperlipoproteinemia: Increased ___
VLDL with increased chylomicrons
Total cholesterol level very low,
triglyceride level nearly undetectable, LDL and Apo B-100
absent
Abetalipoproteinemia
Unable to synthesize apo B-100
and apo B-48, low total cholesterol level and normal to low
triglyceride level
Hypobetalipoproteinemia
Severely elevated triglyceride
level and low HDL level
Hypoalphalipoproteinemia
HDL absent, apo A-I and apo A-II very low
levels, LDL low, total cholesterol level low, triglyceride level
normal to slightly increase
Tangier disease