1. Cholesterol

2. Lipoprotein Lipid Apolipoproteins
Soluble in organic solvents and nearly insoluble in water
Yield fatty acids on hydrolysis
Complex alcohols that combine with fatty acids to form esters
Lipoprotein
An association of a core lipids with coat phospholipid and protein
For solubility
Apolipoproteins
Protein components of lipoprotein.

3. Classification of Clinically Important lipids

4. Structure of cholesterol

5. Cholesterol biosynthesis

6. Esterification of cholesterol mediated by ACAT & LCA

7. Structure of a typical lipoprotein particle

10. apo B-100—containing lipoproteins
VLDL, IDL, Lp(a), LDL

11. Contributors to total cholesterol in normal people
LDL
Two thirds
HDL
One third
IDL and Lp(a)
2 to 3 mg/dL (each)
Total chol = VLDL chol + LDL chol + HDL chol

12. Classification of LDL.Total. and HDL Cholesterol (mg/dL)

13. Reference methods
To establish the accuracy of lipid and lipoprotein measurements
Using the same basis (protocol ) for accuracy that had been used in developing the relationships between lipid and lipoprotein concentration and CHD.
From studies, cut points for the risk characterization in patients were derived.

14. The accuracy of existing or newly developed methods could be assessed.

15. Methods and procedures commonly used
Reference Method (total cholesterol)
Chemical method
Hydrolyze the cholesteryl esters. alcoholic KOH
extracted from the mixture with hexane
dried in vacuo
acetic acid, acetic anhydride, and sulfuric acid
Color development, 620 nm
pure cholesterol as the calibrator.
Expressed as mg/dL = mmoI/L x 38.7

16. HDL cholesterol Reference Method Prepare the HDL-containing fraction.
a combination of ultracentrifugation and polyanion precipitation
Ultracentrifugation
Supernate
VLDL and any chylomicrons accumulate as a floating layer
Infranate
IDL, LDL, Lp(a), HDL, and the other serum proteins
Precipitation with heparin sulfate and MnCl2
Supernate HDL
Precipitate IDL, LDL, Lp(a)
The cholesterol in HDL fraction is then quantitated

17. V-LDL & LDL cholesterol
VLDL chol = [Total chol] – [d > 1.006g/mL chol]
LDL cholesterol
Cholesterol infranate – cholesterol supernate
(IDL, LDL, Lp(a), HDL— HDL fraction)
The Friedewald Equation
[LDL choI] = [Total chol] - [HDL chol]-[Triglyceride]/5
Unacceptable at TG concentrations > 400 mgldL

18. Methods Reference methods Routine Methods
are complex, time consuming, at least partially manual, and require a high level of expertise for reliable operation
Routine Methods
Enzymatic methods

19. Enzymatic method

20. Interference Competition with the oxidation reaction
bilirubin, ascorbic acid, and hemoglobin.
adding substances such as bilirubin oxidase and dual wavelength readings to minimize the effects of hemolysis
β-hydroxy sterols and plant sterols (e.g., β-sitosterol) can also react.
are generally at very low concentrations ( so,not significant)

21. Sources of Variation in Lipid and Lipoprotein Measurements
Analytical Variation
Physiological Variation
Contribute about 70 to 98% of the overall variance
Variation for triglyceride is considerably higher

23. +, minimal to moderate increase
++, moderate to high increase
-, minimal to moderate decrease
-, moderate to high decrease
NC, essentially no change or trend.

24. Recommendations Cholesterol Triglyceride, HDL and LDL cholesterol
Two serial samples obtained at least 1 wk apart be used
Fasting or non-fasting
Triglyceride, HDL and LDL cholesterol
Two to three serial specimens are recommended
12-h fast, or 9-h
Specimens
Serum or plasma (EDTA plasma)

25. Sampling Specimen storage in the same position on each occasion
Serum or plasma should be removed from cells within 3 h
Specimens can be stored for up to 3 d at 4 °C
Up to several wk at —20 °C
at —70 °C or lower for longer periods