LIPID Determination Flashcards
LABORATORY TEST FOR
LIPOPROTEIN AND LIPID DISORDER
- The patient should remain on a regular diet for at least 3 weeks prior to the blood sample
being taken. - There should be no significant weight gain or loss.
- No consumption of alcohol for at least 2 days
-The sample must be collected after a fast of atleast 12 hour
Triglyceride Determination methods
Zilversmith and Van Handel
Enzymatic Method
Zilversmith and Van Handel
◦ 1st step: extract using organic
solvents like
Ether and alcohol
Reagent used 1st step in Zilversmith and Van Handel
Bloor’s reagent
What added in 2nd step in Zilversmith and Van Handel
KOH (potassium hydroxide)
In 3rd step what does it measure in Zilversmith and Van Handel
Glycerol
In 3rd step in zilversmith and van handel the Oxidize glycerol by periodate solution of
Formaldehyde
4th step in zilversmith and van handel the color reaction of formaldehyde is
Pink chromopore
Steps of zilversmith and van handel
Step 1: extracting using organic solvent
Step 2: add KOH
Step 3: measurement of glycerol
Step 4: color reaction of formaldehyde (pink chromopore)
It is a method Uses Lipase – no extraction needed
Enzymatic method
Triglyceride + 3 H2O → Glycerol + 3 F.A. What enzyme is used
Lipase
Glycerol + ATP → Glycerophosphate + ADP what enzyme used
Glycerokinase
- A) Glycerophosphate + O2 → Dihydroxyacetone + H2O2 what enzymes used
Glycerophosphate oxidase
- B) Glycerophosphate + NAD → Dihydroxyacetone + NADH + H
what are the enzymes used
Glycerophosphate dehydrogenase
NADH + Tetrazolium dye → Formazan + NAD what are the enzymes used
Diaphorase
ADP + Phosphoenol pyruvate →ATP + Pyruvate what enzymes is used
Pyvurate kinase
Pyruvate + NADH + H → Lactate + NAD
What enzymes is used
Lactate dehydrogenase
DETERMINATION
OF PLASMA
TRIGLYCERIDES
Hydrolysis of triglyceride to form glycerol and free fatty acids
Measurement of glycerol present (either as glycerol or after conversion to another product)
Measure spectrophotometrically, fluorometrically or colorimetrically
Method used fluorometry
Hantzsch method
Hantzsch method end color
Yellow
Wavelength used in hantzsch method
400-485nm
ATP III Classification for TAG Values
Normal
Borderline high
High
Very high
Normal triglycerides result/reference value
<150mg/dl
Borderline high of triglyceride result/reference value
150-199mg/dl
High of triglycerides reference value/ result
200-499 mg/dl
Very high of triglyceride result/reference value
> 500mg/dl
Reference value of mild elevation
<250mg/dl or 2.8 mmol/L
Reference value for hyperlipoproteinemia
250-500mg/dl or 2.8-5.7mmol/L
Reference value of increase risk pancreatitis
> 500mg/dl or > 5.7mmol/L
Clinical significance triglycerides increase
◦ Hyperlipoproteinemia Type I, IIb, III and
IV and V
◦ Alcoholism
◦ Nephrotic Syndrome
◦ Hypothyroidism
◦ Pancreatitis
Clinical significance triglycerides decrease
◦ Malabsorption Syndrome
◦ Hyperthyroidism
◦ Malnutrition
◦ Brain Infarction
DETERMINATION
OF Total
Cholesterol
Enzymatic method
Faster to perform determination of cholesterol
Enzymatic method
Use less corrosive chemicals while determining cholesterol
Enzymatic method
To diminish the problems associated
with esters and other sterols
Enzymatic method
Hydrolysis of cholesterol e
Enzymatic method
PRINCIPLE of determination cholesterol
◦ Hydrolysis; Cholesterol esters - cholesterol
esterase – cholesterol + fatty acics
◦ Oxidation: Cholesterol + O2 cholesterol
oxidase – cholest-4-en-3-one + H2O2
◦ 2 H2O2 + 4-aminophenazone – peroxidase –
quinoneimine dye
◦ Measure absorbance at 500 nm
Reference value of cholesterol
125mg/dl or 3.2 mmol/L
Conversion of cholesterol mg/dl to mmol/l
0.0259
CHEMICAL
METHODS
Lieberman-burchard (L-B) procedure
Salkowski reaction
one step direct method
(simplest approach)
Lieberman-burchard procedure
Measurement/wavelength of lieberman-burchard procedure
410nm
Lieberman- burchard Other serum constituents such
as
Hemoglobin and bilirubin
End product of salkowski reaction
Cholestadienyldisulfonic acid
End color of salkowski reaction
Red
Abell- Kendall Method has 3 method step
Saponification
Extraction
Colorimetry
Precipitation of cholesterol esters after
extractiuon separate esterified from
free cholesterol, permitting
measurement of only the free fraction
Abell-kendall method
Methods for
total
cholesterol
determination
Bloor’s method
Abell-kendall method
Enzymatic method
2 enzymes involved cholesterol determination
Cholesterol esterase
Cholesterol oxidase
Enzymes that converts esterified
cholesterol into free cholesterol
Cholesterol esterase
Enzymes that oxidize into H2O2
Cholesterol oxidase
Enzymes that oxidize into H2O2
Cholesterol oxidase
Abell, Levy and
Brodie Method
CDC Reference Method
Hydrolysis → Alcoholic KOH
Extraction → Hexane
Leibermann-Burchard Reaction
Current Reference Method – GC-MS
Interference competes with oxidation or
reacts with peroxide
Enzymatic
Linearity of cholesterol interference
600-700 mg/dl
Interference specimen for bilirubin
Icteric and lipemic specimen
Icteric and lipemic specimen – bilirubin
absorbs light at ______ nm
500 nm
falsely increased cholesterol
Hemolysis
Summary of Clinical Significance increases cholesterol
◦ Hyperlipoproteinemia Type II, III and IV
◦ Biliary Cirrhosis
◦ Alcoholism
◦ Nephrotic Syndrome
◦ Primary Hypothyroidism
◦ DM – poorly controlled
Summary of Clinical Significance decreased cholesterol
◦ Severe hepatocellular disease
◦ Malabsorption Syndrome
◦ Hyperthyroidism
◦ Malnutrition
◦ Severe Burns
Conversion factor of cholesterol mmol/L in LDL
0.026
Conversion factor of triglyceride mmol/L in LDL
0.0113