High Blood Cholesterol 

Cholesterol is a fat-soluble  substance produced by the liver and  found in various foods, such as eggs, cheese, milk, bacon, lard and fatty meats.  Since fats do not dissolve in water,  cholesterol must be coated by special proteins called lipoproteins,  allowing  it to circulate in  the blood. 

When  cholesterol is measured  in the blood, three major fractions are found: 1) theTotal Cholesterol (TC) measures  cholesterol contained in all lipoproteins in the blood, and  should be less than 200 mg/dl. 

2) the High Density Lipoprotein or HDL cholesterol (HDL-C),  should be over 40 mg/dl for men and  over 50 mg/dl for women. 

3) theLow Density Lipoprotein  or LDL cholesterol (LDL-C),  is  calculated by subtracting the HDL  cholesterol and 1/5 the measured level of blood fats known as triglycerides from  the total cholesterol.  Target goals for LDL than 70 mg/dl for persons at elevated risk of heart attack, stroke, and/or other cardiovascular diseases--generally it should be less than 100 to 130  mg/dl. 

LDL cholesterol is created by  the liver and is degraded by liver and other cells which manifest LDL receptors  on their surfaces. 

LDL is called the "bad cholesterol" commonly, and is created in liver cells by a process which places lipoproteins--complex molecules containing a protein unit (water soluble) on one end, and a fat soluble lipid tail on the other.  The liver cell lines up the protein ends of the lipoproteins in a sheet--side by side--then wraps the sheet around--into a sphere--with the fatty tails converging in the center of the sphere.  This structure has other special proteins associated with it which identify it as a Low Density Lipoptotein, so called because the fatty core, rich in fat and cholesterol, causes it to have low density (fats float in water). 

If  the production  of LDL  cholesterol exceeds the ability  of  liver and other cells  to remove it from the bloodstream and break it down, the level  of LDL in the bloodstream rises,  and  cholesterol tends  to be deposited on and in cells lining  the inside walls of arteries, critically in  the heart (coronary) and brain (carotids and cerebral) arterial trees. 

Too much cholesterol in the blood, or high blood cholesterol, can be serious. People with high blood cholesterol have a greater chance of getting heart disease. High blood cholesterol on its own does not cause symptoms, so many people are unaware that their cholesterol level is too high.

Cholesterol can build up on the walls of your arteries (blood vessels that carry blood from the heart to other parts of the body). This buildup of cholesterol is called plaque (plak). Over time, plaque can cause narrowing of the arteries. This is called atherosclerosis (ath-er-o-skler-O-sis), or hardening of the arteries.

The illustration shows a normal artery with normal blood flow (Figure A) and an artery containing plaque buildup (Figure B).

Special arteries, called coronary arteries, bring blood to the heart. Narrowing of your coronary arteries due to plaque can stop or slow down the flow of blood to your heart. When the arteries narrow, the amount of oxygen-rich blood is decreased. This is called coronary artery disease (CAD). Large plaque areas can lead to chest pain called angina (an-JI-nuh or AN-juh-nuh). Angina happens when the heart does not receive enough oxygen-rich blood. Angina is a common symptom of CAD.

Some plaques have a thin covering and burst (rupture), releasing fat and cholesterol into the bloodstream. The release of fat and cholesterol may cause your blood to clot. A clot can block the flow of blood. This blockage can cause angina or a heart attack.

Lowering your cholesterol level decreases your chance for having a plaque burst and cause a heart attack. Lowering cholesterol may also slow down, reduce, or even stop plaque from building up.

Plaque and resulting health problems can also occur in arteries elsewhere in the body.