LIPID AND LIPOPROTEIN METHODOLOGY Flashcards
Quiz
they are fatty, waxy, or oily compounds that are essential to many body functions and serve as the building blocks for all living cells.
Lipids
Function of lipids:
help regulate hormones
transmit nerve impulses
cushion organs
store energy in the form of body fat
Disorders of lipids
Arteriosclerosis
obesity
HTN
DM other abnormalities
Indications for Lipid Profile include:
⁃ Screening for primary & secondary hyperlipidemias
⁃ Monitoring for risk of atherosclerosis
⁃ Monitoring treatment of hyperlipidemias/Dyslipidemia
They are the plasma lipids of most interest in the diagnosis and management of lipoprotein disorders
CHOLESTEROL and TRIGLYCERIDE
The term used for elevated lipids and cholesterol
HYPERLIPIDEMIAS
Biological variations:
Age
Sex
Season
Food intake
Medical conditions
Acute illness
Life-style
Fasting requirement before specimen collection
12 hours
The concentration of LDL-C/HDL-C ______ after eating
declines
They are are cleared within 6-9hrs and their presence after 12hrs fast is abnormal.
Chylomicrons
______ causes the decreases of as much 10% in concentration of ________________
Posture
TC, LDL-C, HDL-C and apo-A-1 and B
Patient to be seated for _________ prior to sampling to prevent hemoconcentration.
5min
Prolonged venous occlusion leads to increase in cholesterol conc by _________
10-15%
_________ produces a slight decrease in conc of cholesterol and TG.
Mild exercise
Those who walk for about 4 hours each week have an average cholesterol____ lower and HDL-C ____ higher than inactive persons
5%
3.4%
The cyclical variation in cholesterol is not observed with __________.
anovulatory cycles
A high fat diet increases serum _____
Triglyceride
Ingestion of ___________ reduces cholesterol
monounsaturated fat
___________ is reduced when sucrose intake is reduced.
Plasma triglyceride conc
A high carbohydrate diet decreases the serum conc. of ____, ___, _______ and _____.
VLDL-C
TG
cholesterol
protein
Large protein meals at lunch or in the evening also increase the serum cholesterol for atleast ________ after a meal.
1 hour
In vegeterian individuals, conc. of ____ & _____ are reduced by 37 % and 12%.
LDL
VLDL-C
The plasma cholesterol, triglyceride and LDL cholesterol conc. are higher by about ___, ___ and _____ respectively in smokers than in non smokers.
3 %
9.1 %
1.7 %
_____ is lower in smokers than in non smokers
HDL cholesterol
Alcohol ingestion: - When moderate amount of alcohol is ingested for 1wk, the serum TG conc is increased by more than _________.
20mg/dL
Prolonged moderate ingestion may increase HDL-C conc —> reduced plasma conc of __________.
cholesterol ester transfer protein(CETP)
What are the two specimen of choice?
Plasma
Serum
Plasma and serum - Either can be used when ___, ____ and _____ are measured
TC
TG
HDL-C
Plasma is preferred when lipoprotein are measured by:
- Ultracentrifugation
- Electrophoretic methods
________ can be used when it is necessary to store samples for weeks or months.
Serum
Measurements in the ________ seem to be little lower than _________
capillary samples
venous samples
What are the three anticoagulant used in Lipid determination?
Citrate
Heparin
EDTA
It exert large osmotic effect resulting in falsely low plasma lipid and lipoprotein concentration.
Citrate
Anticoagulant used because of its high M.W can alter electrophoretic mobility of lipoproteins.
Heparin
Preferred anticoagulant even though TC and TG conc in this anticoagulant’s plasma are 3% lower than in serum.
EDTA
Storage:
- ___________ can be satisfactorily analyzed in frozen samples.
- ____________can also be measured in frozen samples.
TC, TG, HDL-C
Apolipoproteins
Serum or plasma must be stored at ______ if stored for long time.
- 70°C
For short time storage (upto a month or two) the sample can be kept
at _____
-2 degrees
What are the two main cholecterol estimation methods?
Chemical methods
Enzymatic methods
Methods under chemical methods for cholesterol estimation
Abell Kendall Method
Bloors Methods
Former reference method for cholesterol estimation with 3 step.
Abell Kendall Method
What is the principle of AK method
3 step method
Abell Kendall Method is measured using what reaction?
L-B reaction / Liebermann-Burchardt reaction
What is the end product of L-B reaction?
Bluish green solution
Principle of Bloors method
2 step method
Reagent used in Bloors method
Alcohol ether mixture
Color developers of L-B reaction
Glacial acetic acid
Acetic anhyride
Concentrated Hydrogen sulfate
Method under enzymatic methods for cholesterol estimation
Cholesterol oxidase method
Routine lab-assay of choice
Cholesterol oxidase method
Three enzymes under Cholesterol oxidase method
Cholesterol esterase
Cholesterol oxidase
Peroxidase
Reaction used in Cholesterol oxidase method
Trinder’s reaction
Wavelength of Cholesterol oxidase method
500nm
End product of Trinder’s reaction
Quinoneimine dye (Red)
H2O
Linearity of Cholesterol oxidase method
600 - 700mg/dL (15.54 - 18.13mmol/L)
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
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%