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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).

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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