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1
Determination of HDL-Cholesterol
They are a good type of cholesterol containing 52% protein , 28%phospholipids and 20% cholesterol . All lipoproteins transfer lipids from cell to cell except HDL-C remove cholesterol from the cells to the liver and change it to bile acids therefore called scavenger .
HDL is a major circulating lipoprotein in a beta lipoproteinemia patients . It is produced in the liver and intestine , it travels in the blood stream picking up cholesterol and the cholesterol to other lipoproteins to transport it back to the liver .
There are two types of HDL-C :-
HDL2 ⟹ M.Wt = 375 K.Dalton
HDL3 ⟹ M.Wt = 200 K.Dalton
The removing of cholesterol by HDL result from enzymaticactivity for Lecithin Cholesterol Acyl Transference (LCAT) by converted of free cholesterol cholesterol ester .
Principle :-
All methods depends on :-
1-Isolation of HDL
2-Determination of cholesterol by HDL isolation .
One of the important methods to isolate HDL is precipitation with polyanions solution . This method depend on ability of precipitate reagents to precipitate all lipoprotein except HDL , such as (Heparin - Manganese chloride , Dextrin sulphate –Magnesium chloride – Sodium phospho tungstate and poly ethylene glycol).
2
Clinical significance :-
We are depending on HDL ratio to know Coronary Artry Diseases (CAD) for human that age less 50 years .
Many factors effect on atherosclerosis disease :-
1-Smoking decreasing HDL
2- Obesity decreasing HDL
3-Physical inactivity
4-Hypo alpha lipo proteinemia
5-In puberty
Normal values :-
Males 30 – 60 mg / dL
Females 38 – 75 mg / dL